手把手教你整合最优雅SSM框架：SpringMVC + Spring + MyBatis

深藏阁楼爱情的钟 2022-07-14 08:16 101阅读 0赞

> > http://blog.csdn.net/qq598535550/article/details/51703190  
> > 
> > 
> > 我们看招聘信息的时候，经常会看到这一点，需要具备SSH框架的技能；而且在大部分教学课堂中，也会把SSH作为最核心的教学内容。   
> > 但是，我们在实际应用中发现，SpringMVC可以完全替代Struts，配合注解的方式，编程非常快捷，而且通过restful风格定义url，让地址看起来非常优雅。   
> > 另外，MyBatis也可以替换Hibernate，正因为MyBatis的半自动特点，我们程序猿可以完全掌控SQL，这会让有数据库经验的程序猿能开发出高效率的SQL语句，而且XML配置管理起来也非常方便。   
> > 好了，如果你也认同我的看法，那么下面我们一起来做整合吧！
> 
> 在写代码之前我们先了解一下这三个框架分别是干什么的？   
> 相信大以前也看过不少这些概念，我这就用大白话来讲，如果之前有了解过可以跳过这一大段，直接看代码！
> 
> 1.  SpringMVC：它用于web层，相当于controller（等价于传统的servlet和struts的action），用来处理用户请求。举个例子，用户在地址栏输入http://网站域名/login，那么springmvc就会拦截到这个请求，并且调用controller层中相应的方法，（中间可能包含验证用户名和密码的业务逻辑，以及查询数据库操作，但这些都不是springmvc的职责），最终把结果返回给用户，并且返回相应的页面（当然也可以只反馈josn/xml等格式数据）。springmvc就是做前面和后面过程的活，与用户打交道！！
> 2.  Spring：太强大了，以至于我无法用一个词或一句话来概括它。但与我们平时开发接触最多的估计就是IOC容器，它可以装载bean（也就是我们java中的类，当然也包括service dao里面的），有了这个机制，我们就不用在每次使用这个类的时候为它初始化，很少看到关键字new。另外spring的aop，事务管理等等都是我们经常用到的。
> 3.  MyBatis：如果你问我它跟鼎鼎大名的Hibernate有什么区别？我只想说，他更符合我的需求。第一，它能自由控制sql，这会让有数据库经验的人（当然不是说我啦~捂脸~）编写的代码能搞提升数据库访问的效率。第二，它可以使用xml的方式来组织管理我们的sql，因为一般程序出错很多情况下是sql出错，别人接手代码后能快速找到出错地方，甚至可以优化原来写的sql。
> 
> --------------------
> 
> ## SSM框架整合配置 ##
> 
> 好了，前面bb那么多，下面我们真正开始敲代码了~
> 
> 首先我们打开IED，我这里用的是eclipse（你们应该也是用的这个，对吗？），创建一个动态web项目，建立好相应的目录结构（重点！）
> 
> ![项目结构图][20160618002041099]
> 
> （打了马赛克是因为这里还用不到，你们不要那么污好不好？）
> 
> 我说一下每个目录都有什么用吧（第一次画表格，我发现markdown的表格语法很不友好呀~）   
> 这个目录结构同时也遵循maven的目录规范~
> 
> <table style="box-sizing: border-box; border-collapse: collapse; border-spacing: 0px; max-width: 100%; background: transparent; margin: 0px; padding: 0px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: baseline; width: 731px; font-family: &quot;microsoft yahei&quot;;"> 
>  <thead style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <th style="box-sizing: border-box; text-align: left; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">文件名</th> 
>    <th style="box-sizing: border-box; text-align: left; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">作用</th> 
>   </tr> 
>  </thead> 
>  <tbody style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">src</td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">根目录，没什么好说的，下面有main和test。</td> 
>   </tr> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;"> 
>     <ul style="box-sizing: border-box; margin: 0px 0px 22px; padding: 0px; font-family: &quot;Microsoft YaHei&quot;; list-style: square inside; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>      <li> main </li> 
>     </ul></td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">主要目录，可以放java代码和一些资源文件。</td> 
>   </tr> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;"> 
>     <ul style="box-sizing: border-box; margin: 0px 0px 22px; padding: 0px; font-family: &quot;Microsoft YaHei&quot;; list-style: square inside; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>      <li> 
>       <ul style="box-sizing: border-box; margin: 0px; padding: 0px; list-style: square inside; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>        <li> java </li> 
>       </ul> </li> 
>     </ul></td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">存放我们的java代码，这个文件夹要使用Build Path -&gt; Use as Source Folder，这样看包结构会方便很多，新建的包就相当于在这里新建文件夹咯。</td> 
>   </tr> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;"> 
>     <ul style="box-sizing: border-box; margin: 0px 0px 22px; padding: 0px; font-family: &quot;Microsoft YaHei&quot;; list-style: square inside; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>      <li> 
>       <ul style="box-sizing: border-box; margin: 0px; padding: 0px; list-style: square inside; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>        <li> resources </li> 
>       </ul> </li> 
>     </ul></td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">存放资源文件，譬如各种的spring，mybatis，log配置文件。</td> 
>   </tr> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;"> 
>     <ul style="box-sizing: border-box; margin: 0px 0px 22px; padding: 0px; font-family: &quot;Microsoft YaHei&quot;; list-style: square inside; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>      <li> 
>       <ul style="box-sizing: border-box; margin: 0px; padding: 0px; list-style: square inside; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>        <li> 
>         <ul style="box-sizing: border-box; margin: 0px; padding: 0px; list-style-position: inside; list-style-image: initial; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>          <li> mapper </li> 
>         </ul> </li> 
>       </ul> </li> 
>     </ul></td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">存放dao中每个方法对应的sql，在这里配置，无需写daoImpl。</td> 
>   </tr> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;"> 
>     <ul style="box-sizing: border-box; margin: 0px 0px 22px; padding: 0px; font-family: &quot;Microsoft YaHei&quot;; list-style: square inside; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>      <li> 
>       <ul style="box-sizing: border-box; margin: 0px; padding: 0px; list-style: square inside; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>        <li> 
>         <ul style="box-sizing: border-box; margin: 0px; padding: 0px; list-style-position: inside; list-style-image: initial; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>          <li> spring </li> 
>         </ul> </li> 
>       </ul> </li> 
>     </ul></td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">这里当然是存放spring相关的配置文件，有dao service web三层。</td> 
>   </tr> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;"> 
>     <ul style="box-sizing: border-box; margin: 0px 0px 22px; padding: 0px; font-family: &quot;Microsoft YaHei&quot;; list-style: square inside; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>      <li> 
>       <ul style="box-sizing: border-box; margin: 0px; padding: 0px; list-style: square inside; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>        <li> 
>         <ul style="box-sizing: border-box; margin: 0px; padding: 0px; list-style-position: inside; list-style-image: initial; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>          <li> sql </li> 
>         </ul> </li> 
>       </ul> </li> 
>     </ul></td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">其实这个可以没有，但是为了项目完整性还是加上吧。</td> 
>   </tr> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;"> 
>     <ul style="box-sizing: border-box; margin: 0px 0px 22px; padding: 0px; font-family: &quot;Microsoft YaHei&quot;; list-style: square inside; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>      <li> 
>       <ul style="box-sizing: border-box; margin: 0px; padding: 0px; list-style: square inside; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>        <li> 
>         <ul style="box-sizing: border-box; margin: 0px; padding: 0px; list-style-position: inside; list-style-image: initial; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>          <li> webapp </li> 
>         </ul> </li> 
>       </ul> </li> 
>     </ul></td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">这个貌似是最熟悉的目录了，用来存放我们前端的静态资源，如jsp js css。</td> 
>   </tr> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;"> 
>     <ul style="box-sizing: border-box; margin: 0px 0px 22px; padding: 0px; font-family: &quot;Microsoft YaHei&quot;; list-style: square inside; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>      <li> 
>       <ul style="box-sizing: border-box; margin: 0px; padding: 0px; list-style: square inside; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>        <li> 
>         <ul style="box-sizing: border-box; margin: 0px; padding: 0px; list-style-position: inside; list-style-image: initial; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>          <li> resources </li> 
>         </ul> </li> 
>       </ul> </li> 
>     </ul></td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">这里的资源是指项目的静态资源，如js css images等。</td> 
>   </tr> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;"> 
>     <ul style="box-sizing: border-box; margin: 0px 0px 22px; padding: 0px; font-family: &quot;Microsoft YaHei&quot;; list-style: square inside; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>      <li> 
>       <ul style="box-sizing: border-box; margin: 0px; padding: 0px; list-style: square inside; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>        <li> 
>         <ul style="box-sizing: border-box; margin: 0px; padding: 0px; list-style-position: inside; list-style-image: initial; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>          <li> WEB-INF </li> 
>         </ul> </li> 
>       </ul> </li> 
>     </ul></td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">很重要的一个目录，外部浏览器无法访问，只有羡慕内部才能访问，可以把jsp放在这里，另外就是web.xml了。你可能有疑问了，为什么上面java中的resources里面的配置文件不妨在这里，那么是不是会被外部窃取到？你想太多了，部署时候基本上只有webapp里的会直接输出到根目录，其他都会放入WEB-INF里面，项目内部依然可以使用classpath:XXX来访问，好像IDE里可以设置部署输出目录，这里扯远了~</td> 
>   </tr> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;"> 
>     <ul style="box-sizing: border-box; margin: 0px 0px 22px; padding: 0px; font-family: &quot;Microsoft YaHei&quot;; list-style: square inside; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>      <li> test </li> 
>     </ul></td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">这里是测试分支。</td> 
>   </tr> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;"> 
>     <ul style="box-sizing: border-box; margin: 0px 0px 22px; padding: 0px; font-family: &quot;Microsoft YaHei&quot;; list-style: square inside; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>      <li> 
>       <ul style="box-sizing: border-box; margin: 0px; padding: 0px; list-style: square inside; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>        <li> java </li> 
>       </ul> </li> 
>     </ul></td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">测试java代码，应遵循包名相同的原则，这个文件夹同样要使用Build Path -&gt; Use as Source Folder，这样看包结构会方便很多。</td> 
>   </tr> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;"> 
>     <ul style="box-sizing: border-box; margin: 0px 0px 22px; padding: 0px; font-family: &quot;Microsoft YaHei&quot;; list-style: square inside; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>      <li> 
>       <ul style="box-sizing: border-box; margin: 0px; padding: 0px; list-style: square inside; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>        <li> resources </li> 
>       </ul> </li> 
>     </ul></td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">没什么好说的，好像也很少用到，但这个是maven的规范。</td> 
>   </tr> 
>  </tbody> 
> </table>
> 
> --------------------
> 
> 我先新建好几个必要的包，并为大家讲解一下每个包的作用，顺便理清一下后台的思路~
> 
> ![包结构图][20160618004306660]
> 
> <table style="box-sizing: border-box; border-collapse: collapse; border-spacing: 0px; max-width: 100%; background: transparent; margin: 0px; padding: 0px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: baseline; width: 731px; font-family: &quot;microsoft yahei&quot;;"> 
>  <thead style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <th style="box-sizing: border-box; text-align: left; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">包名</th> 
>    <th style="box-sizing: border-box; text-align: left; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">名称</th> 
>    <th style="box-sizing: border-box; text-align: left; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">作用</th> 
>   </tr> 
>  </thead> 
>  <tbody style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">dao</td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">数据访问层（接口）</td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">与数据打交道，可以是数据库操作，也可以是文件读写操作，甚至是redis缓存操作，总之与数据操作有关的都放在这里，也有人叫做dal或者数据持久层都差不多意思。为什么没有daoImpl，因为我们用的是mybatis，所以可以直接在配置文件中实现接口的每个方法。</td> 
>   </tr> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">entity</td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">实体类</td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">一般与数据库的表相对应，封装dao层取出来的数据为一个对象，也就是我们常说的pojo，一般只在dao层与service层之间传输。</td> 
>   </tr> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">dto</td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">数据传输层</td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">刚学框架的人可能不明白这个有什么用，其实就是用于service层与web层之间传输，为什么不直接用entity（pojo）？其实在实际开发中发现，很多时间一个entity并不能满足我们的业务需求，可能呈现给用户的信息十分之多，这时候就有了dto，也相当于vo，记住一定不要把这个混杂在entity里面，答应我好吗？</td> 
>   </tr> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">service</td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">业务逻辑（接口）</td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">写我们的业务逻辑，也有人叫bll，在设计业务接口时候应该站在“使用者”的角度。额，不要问我为什么这里没显示！IDE调皮我也拿它没办法~</td> 
>   </tr> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">serviceImpl</td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">业务逻辑（实现）</td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">实现我们业务接口，一般事务控制是写在这里，没什么好说的。</td> 
>   </tr> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">web</td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">控制器</td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">springmvc就是在这里发挥作用的，一般人叫做controller控制器，相当于struts中的action。</td> 
>   </tr> 
>  </tbody> 
> </table>
> 
> --------------------
> 
> 还有最后一步基础工作，导入我们相应的jar包，我使用的是maven来管理我们的jar，所以只需要在`poom.xml`中加入相应的依赖就好了，如果不使用maven的可以自己去官网下载相应的jar，放到项目WEB-INF/lib目录下。关于maven的学习大家可以看[慕课网的视频教程][Link 1]，这里就不展开了。我把项目用到的jar都写在下面，版本都不是最新的，大家有经验的话可以自己调整版本号。另外，所有jar都会与项目一起打包放到我的[github][]上，喜欢的给个star吧~
> 
> poom.xml
> 
>     <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
>         <modelVersion>4.0.0</modelVersion>
>         <groupId>com.soecode.ssm</groupId>
>         <artifactId>ssm</artifactId>
>         <packaging>war</packaging>
>         <version>0.0.1-SNAPSHOT</version>
>         <name>ssm Maven Webapp</name>
>         <url>http://github.com/liyifeng1994/ssm</url>
>         <dependencies>
>             
>             <dependency>
>                 <groupId>junit</groupId>
>                 <artifactId>junit</artifactId>
>                 <version>4.11</version>
>             </dependency>
>     
>             
>             
>             <dependency>
>                 <groupId>ch.qos.logback</groupId>
>                 <artifactId>logback-classic</artifactId>
>                 <version>1.1.1</version>
>             </dependency>
>     
>             
>             <dependency>
>                 <groupId>mysql</groupId>
>                 <artifactId>mysql-connector-java</artifactId>
>                 <version>5.1.37</version>
>                 <scope>runtime</scope>
>             </dependency>
>             <dependency>
>                 <groupId>c3p0</groupId>
>                 <artifactId>c3p0</artifactId>
>                 <version>0.9.1.2</version>
>             </dependency>
>     
>             
>             <dependency>
>                 <groupId>org.mybatis</groupId>
>                 <artifactId>mybatis</artifactId>
>                 <version>3.3.0</version>
>             </dependency>
>             <dependency>
>                 <groupId>org.mybatis</groupId>
>                 <artifactId>mybatis-spring</artifactId>
>                 <version>1.2.3</version>
>             </dependency>
>     
>             
>             <dependency>
>                 <groupId>taglibs</groupId>
>                 <artifactId>standard</artifactId>
>                 <version>1.1.2</version>
>             </dependency>
>             <dependency>
>                 <groupId>jstl</groupId>
>                 <artifactId>jstl</artifactId>
>                 <version>1.2</version>
>             </dependency>
>             <dependency>
>                 <groupId>com.fasterxml.jackson.core</groupId>
>                 <artifactId>jackson-databind</artifactId>
>                 <version>2.5.4</version>
>             </dependency>
>             <dependency>
>                 <groupId>javax.servlet</groupId>
>                 <artifactId>javax.servlet-api</artifactId>
>                 <version>3.1.0</version>
>             </dependency>
>     
>             
>             
>             <dependency>
>                 <groupId>org.springframework</groupId>
>                 <artifactId>spring-core</artifactId>
>                 <version>4.1.7.RELEASE</version>
>             </dependency>
>             <dependency>
>                 <groupId>org.springframework</groupId>
>                 <artifactId>spring-beans</artifactId>
>                 <version>4.1.7.RELEASE</version>
>             </dependency>
>             <dependency>
>                 <groupId>org.springframework</groupId>
>                 <artifactId>spring-context</artifactId>
>                 <version>4.1.7.RELEASE</version>
>             </dependency>
>             
>             <dependency>
>                 <groupId>org.springframework</groupId>
>                 <artifactId>spring-jdbc</artifactId>
>                 <version>4.1.7.RELEASE</version>
>             </dependency>
>             <dependency>
>                 <groupId>org.springframework</groupId>
>                 <artifactId>spring-tx</artifactId>
>                 <version>4.1.7.RELEASE</version>
>             </dependency>
>             
>             <dependency>
>                 <groupId>org.springframework</groupId>
>                 <artifactId>spring-web</artifactId>
>                 <version>4.1.7.RELEASE</version>
>             </dependency>
>             <dependency>
>                 <groupId>org.springframework</groupId>
>                 <artifactId>spring-webmvc</artifactId>
>                 <version>4.1.7.RELEASE</version>
>             </dependency>
>             
>             <dependency>
>                 <groupId>org.springframework</groupId>
>                 <artifactId>spring-test</artifactId>
>                 <version>4.1.7.RELEASE</version>
>             </dependency>
>     
>             
>             <dependency>
>                 <groupId>redis.clients</groupId>
>                 <artifactId>jedis</artifactId>
>                 <version>2.7.3</version>
>             </dependency>
>             <dependency>
>                 <groupId>com.dyuproject.protostuff</groupId>
>                 <artifactId>protostuff-core</artifactId>
>                 <version>1.0.8</version>
>             </dependency>
>             <dependency>
>                 <groupId>com.dyuproject.protostuff</groupId>
>                 <artifactId>protostuff-runtime</artifactId>
>                 <version>1.0.8</version>
>             </dependency>
>     
>             
>             <dependency>
>                 <groupId>commons-collections</groupId>
>                 <artifactId>commons-collections</artifactId>
>                 <version>3.2</version>
>             </dependency>
>         </dependencies>
>         <build>
>             <finalName>ssm</finalName>
>         </build>
>     </project>
>     
>       
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> 
> --------------------
> 
> 下面真的要开始进行编码工作了，坚持到这里辛苦大家了~
> 
> 第一步：我们先在`spring`文件夹里新建`spring-dao.xml`文件，因为spring的配置太多，我们这里分三层，分别是dao service web。
> 
> 1.  读入数据库连接相关参数（可选）
> 2.  配置数据连接池   
>     
>     
>     1.  配置连接属性，可以不读配置项文件直接在这里写死
>     2.  配置c3p0，只配了几个常用的
> 3.  配置SqlSessionFactory对象（mybatis）
> 4.  扫描dao层接口，动态实现dao接口，也就是说不需要daoImpl，sql和参数都写在xml文件上
> 
> spring-dao.xml
> 
>     <?xml version="1.0" encoding="UTF-8"?>
>     <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
>         
>         
>         <context:property-placeholder location="classpath:jdbc.properties" />
>     
>         
>         <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
>             
>             <property name="driverClass" value="${jdbc.driver}" />
>             <property name="jdbcUrl" value="${jdbc.url}" />
>             <property name="user" value="${jdbc.username}" />
>             <property name="password" value="${jdbc.password}" />
>     
>             
>             <property name="maxPoolSize" value="30" />
>             <property name="minPoolSize" value="10" />
>             
>             <property name="autoCommitOnClose" value="false" />
>             
>             <property name="checkoutTimeout" value="10000" />
>             
>             <property name="acquireRetryAttempts" value="2" />
>         </bean>
>     
>         
>         <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
>             
>             <property name="dataSource" ref="dataSource" />
>             
>             <property name="configLocation" value="classpath:mybatis-config.xml" />
>             
>             <property name="typeAliasesPackage" value="com.soecode.lyf.entity" />
>             
>             <property name="mapperLocations" value="classpath:mapper/*.xml" />
>         </bean>
>     
>         
>         <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
>             
>             <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" />
>             
>             <property name="basePackage" value="com.soecode.lyf.dao" />
>         </bean>
>     </beans>
>       
>        
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> 
> 因为数据库配置相关参数是读取配置文件，所以在`resources`文件夹里新建一个`jdbc.properties`文件，存放我们4个最常见的数据库连接属性，这是我本地的，大家记得修改呀~还有喜欢传到github上“大头虾们”记得删掉密码，不然别人就很容易得到你服务器的数据库配置信息，然后干一些羞羞的事情，你懂的！！
> 
> jdbc.properties
> 
>     jdbc.driver=com.mysql.jdbc.Driver
>     jdbc.url=jdbc:mysql://localhost:3307/ssm?useUnicode=true&characterEncoding=utf8
>     jdbc.username=root
>     jdbc.password=
>       
>        
>         1
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> 
> 友情提示：配置文件中的jdbc.username，如果写成username，可能会与系统环境中的username变量冲突，所以到时候真正连接数据库的时候，用户名就被替换成系统中的用户名（有得可能是administrator），那肯定是连接不成功的，这里有个小坑，我被坑了一晚上！！
> 
> 因为这里用到了mybatis，所以需要配置mybatis核心文件，在`recources`文件夹里新建`mybatis-config.xml`文件。
> 
> 1.  使用自增主键
> 2.  使用列别名
> 3.  开启驼峰命名转换 create\_time -> createTime
> 
> mybatis-config.xml
> 
>     <?xml version="1.0" encoding="UTF-8" ?>
>     <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
>     <configuration>
>         
>         <settings>
>             
>             <setting name="useGeneratedKeys" value="true" />
>     
>             
>             <setting name="useColumnLabel" value="true" />
>     
>             
>             <setting name="mapUnderscoreToCamelCase" value="true" />
>         </settings>
>     </configuration>
>       
>        
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> 
> 第二步：刚弄好dao层，接下来到service层了。在`spring`文件夹里新建`spring-service.xml`文件。
> 
> 1.  扫描service包所有注解 @Service
> 2.  配置事务管理器，把事务管理交由spring来完成
> 3.  配置基于注解的声明式事务，可以直接在方法上@Transaction
> 
> spring-service.xml
> 
>     <?xml version="1.0" encoding="UTF-8"?>
>     <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">
>         
>         <context:component-scan base-package="com.soecode.lyf.service" />
>     
>         
>         <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
>             
>             <property name="dataSource" ref="dataSource" />
>         </bean>
>     
>         
>         <tx:annotation-driven transaction-manager="transactionManager" />
>     </beans>
>       
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> 
> --------------------
> 
> 第三步：配置web层，在`spring`文件夹里新建`spring-web.xml`文件。
> 
> 1.  开启SpringMVC注解模式，可以使用@RequestMapping，@PathVariable，@ResponseBody等
> 2.  对静态资源处理，如js，css，jpg等
> 3.  配置jsp 显示ViewResolver，例如在controller中某个方法返回一个string类型的”login”，实际上会返回”/WEB-INF/login.jsp”
> 4.  扫描web层 @Controller
> 
> spring-web.xml
> 
>     <?xml version="1.0" encoding="UTF-8"?>
>     <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">
>         
>         
>         
>         <mvc:annotation-driven />
>     
>         
>          <mvc:default-servlet-handler/>
>     
>          
>          <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
>             <property name="viewClass" value="org.springframework.web.servlet.view.JstlView" />
>             <property name="prefix" value="/WEB-INF/jsp/" />
>             <property name="suffix" value=".jsp" />
>          </bean>
>     
>          
>          <context:component-scan base-package="com.soecode.lyf.web" />
>     </beans>
>       
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> 
> --------------------
> 
> 第四步：最后就是修改`web.xml`文件了，它在`webapp`的`WEB-INF`下。
> 
> web.xml
> 
>     <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" version="3.1" metadata-complete="true">
>         
>         
>         <servlet>
>             <servlet-name>seckill-dispatcher</servlet-name>
>             <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
>             
>             <init-param>
>                 <param-name>contextConfigLocation</param-name>
>                 <param-value>classpath:spring/spring-*.xml</param-value>
>             </init-param>
>         </servlet>
>         <servlet-mapping>
>             <servlet-name>seckill-dispatcher</servlet-name>
>             
>             <url-pattern>/</url-pattern>
>         </servlet-mapping>
>     </web-app>
>     
>       
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> 
> --------------------
> 
> 我们在项目中经常会使用到日志，所以这里还有配置日志xml，在`resources`文件夹里新建`logback.xml`文件，所给出的日志输出格式也是最基本的控制台s呼出，大家有兴趣查看[logback官方文档][logback]。
> 
> logback.xml
> 
>     <?xml version="1.0" encoding="UTF-8"?>
>     <configuration debug="true">
>         <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
>             
>             <encoder>
>                 <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
>             </encoder>
>         </appender>
>     
>         <root level="debug">
>             <appender-ref ref="STDOUT" />
>         </root>
>     </configuration>
>       
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> 
> --------------------
> 
> 到目前为止，我们一共写了7个配置文件，我们一起来看下最终的配置文件结构图。
> 
> ![配置文件结构图][20160618142208354]
> 
> --------------------
> 
> ## SSM框架应用实例（图书管理系统） ##
> 
> > 一开始想就这样结束教程，但是发现其实很多人都还不会把这个SSM框架用起来，特别是mybatis部分。那我现在就以最常见的“图书管理系统”中【查询图书】和【预约图书】业务来做一个demo吧！
> 
> 首先新建数据库名为`ssm`，再创建两张表：图书表`book`和预约图书表`appointment`，并且为`book`表初始化一些数据，sql如下。
> 
> schema.sql
> 
>     -- 创建图书表
>     CREATE TABLE `book` ( `book_id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT '图书ID', `name` varchar(100) NOT NULL COMMENT '图书名称', `number` int(11) NOT NULL COMMENT '馆藏数量', PRIMARY KEY (`book_id`) ) ENGINE=InnoDB AUTO_INCREMENT=1000 DEFAULT CHARSET=utf8 COMMENT='图书表' -- 初始化图书数据 INSERT INTO `book` (`book_id`, `name`, `number`) VALUES (1000, 'Java程序设计', 10), (1001, '数据结构', 10), (1002, '设计模式', 10), (1003, '编译原理', 10) -- 创建预约图书表 CREATE TABLE `appointment` ( `book_id` bigint(20) NOT NULL COMMENT '图书ID', `student_id` bigint(20) NOT NULL COMMENT '学号', `appoint_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '预约时间' , PRIMARY KEY (`book_id`, `student_id`), INDEX `idx_appoint_time` (`appoint_time`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='预约图书表'
>       
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> 
> --------------------
> 
> 在`entity`包中添加两个对应的实体，图书实体`Book.java`和预约图书实体`Appointment.java`。
> 
> Book.java
> 
>     package com.soecode.lyf.entity;
>     
>     public class Book { 
>     
>         private long bookId;// 图书ID
>     
>         private String name;// 图书名称
>     
>         private int number;// 馆藏数量
>     
>         // 省略构造方法，getter和setter方法，toString方法
>     
>     }
>       
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> 
> Appointment.java
> 
>     package com.soecode.lyf.entity;
>     
>     import java.util.Date;
>     
>     /** * 预约图书实体 */
>     public class Appointment { 
>     
>         private long bookId;// 图书ID
>     
>         private long studentId;// 学号
>     
>         private Date appointTime;// 预约时间
>     
>         // 多对一的复合属性
>         private Book book;// 图书实体
>     
>         // 省略构造方法，getter和setter方法，toString方法
>     
>     }
>       
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> 
> --------------------
> 
> 在`dao`包新建接口`BookDao.java`和`Appointment.java`
> 
> BookDao.java
> 
>     package com.soecode.lyf.dao;
>     
>     import java.util.List;
>     
>     import com.soecode.lyf.entity.Book;
>     
>     public interface BookDao { 
>     
>         /** * 通过ID查询单本图书 * * @param id * @return */
>         Book queryById(long id);
>     
>         /** * 查询所有图书 * * @param offset 查询起始位置 * @param limit 查询条数 * @return */
>         List<Book> queryAll(@Param("offset") int offset, @Param("limit") int limit);
>     
>         /** * 减少馆藏数量 * * @param bookId * @return 如果影响行数等于>1，表示更新的记录行数 */
>         int reduceNumber(long bookId);
>     }
>     
>       
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> 
> AppointmentDao.java
> 
>     package com.soecode.lyf.dao;
>     
>     import org.apache.ibatis.annotations.Param;
>     
>     import com.soecode.lyf.entity.Appointment;
>     
>     public interface AppointmentDao { 
>     
>         /** * 插入预约图书记录 * * @param bookId * @param studentId * @return 插入的行数 */
>         int insertAppointment(@Param("bookId") long bookId, @Param("studentId") long studentId);
>     
>         /** * 通过主键查询预约图书记录，并且携带图书实体 * * @param bookId * @param studentId * @return */
>         Appointment queryByKeyWithBook(@Param("bookId") long bookId, @Param("studentId") long studentId);
>     
>     }
>       
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> 
> 提示：这里为什么要给方法的参数添加`@Param`注解呢？是因为该方法有两个或以上的参数，一定要加，不然mybatis识别不了。上面的`BookDao`接口的`queryById`方法和`reduceNumber`方法只有一个参数`book_id`，所以可以不用加 `@Param`注解，当然加了也无所谓~
> 
> --------------------
> 
> 注意，这里不需要实现dao接口不用编写daoImpl， mybatis会给我们动态实现，但是我们需要编写相应的mapper。   
> 在`mapper`目录里新建两个文件`BookDao.xml`和`AppointmentDao.xml`，分别对应上面两个dao接口，代码如下。
> 
> BookDao.xml
> 
>     <?xml version="1.0" encoding="UTF-8"?>
>     <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
>     <mapper namespace="com.soecode.lyf.dao.BookDao">
>         
>         <select id="queryById" resultType="Book" parameterType="long">
>             
>             SELECT
>                 book_id,
>                 name,
>                 number
>             FROM
>                 book
>             WHERE
>                 book_id = #{bookId}
>         </select>
>     
>         <select id="queryAll" resultType="Book">
>             SELECT
>                 book_id,
>                 name,
>                 number
>             FROM
>                 book
>             ORDER BY
>                 book_id
>             LIMIT #{offset}, #{limit}
>         </select>
>     
>         <update id="reduceNumber">
>             UPDATE book
>             SET number = number - 1
>             WHERE
>                 book_id = #{bookId}
>             AND number > 0
>         </update>
>     </mapper>
>       
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> 
> AppointmentDao.xml
> 
>     <?xml version="1.0" encoding="UTF-8"?>
>     <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
>     <mapper namespace="com.soecode.lyf.dao.AppointmentDao">
>         <insert id="insertAppointment">
>             
>             INSERT ignore INTO appointment (book_id, student_id)
>             VALUES (#{bookId}, #{studentId})
>         </insert>
>     
>         <select id="queryByKeyWithBook" resultType="Appointment">
>             
>             
>             SELECT
>                 a.book_id,
>                 a.student_id,
>                 a.appoint_time,
>                 b.book_id "book.book_id",
>                 b.`name` "book.name",
>                 b.number "book.number"
>             FROM
>                 appointment a
>             INNER JOIN book b ON a.book_id = b.book_id
>             WHERE
>                 a.book_id = #{bookId}
>             AND a.student_id = #{studentId}
>         </select>
>     </mapper>
>       
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> 
> mapper总结：`namespace`是该xml对应的接口全名，`select`和`update`中的`id`对应方法名，`resultType`是返回值类型，`parameterType`是参数类型（这个其实可选），最后`#{...}`中填写的是方法的参数，看懂了是不是很简单！！我也这么觉得~ 还有一个小技巧要交给大家，就是在返回`Appointment`对象包含了一个属性名为`book`的Book对象，那么可以使用`"book.属性名"`的方式来取值，看上面`queryByKeyWithBook`方法的sql。
> 
> --------------------
> 
> `dao`层写完了，接下来`test`对应的`package`写我们测试方法吧。   
> 因为我们之后会写很多测试方法，在测试前需要让程序读入spring-dao和mybatis等配置文件，所以我这里就抽离出来一个`BaseTest`类，只要是测试方法就继承它，这样那些繁琐的重复的代码就不用写那么多了~
> 
> BaseTest.java
> 
>     package com.soecode.lyf;
>     
>     import org.junit.runner.RunWith;
>     import org.springframework.test.context.ContextConfiguration;
>     import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
>     
>     /** * 配置spring和junit整合，junit启动时加载springIOC容器 spring-test,junit */
>     @RunWith(SpringJUnit4ClassRunner.class)
>     // 告诉junit spring配置文件
>     @ContextConfiguration({ "classpath:spring/spring-dao.xml", "classpath:spring/spring-service.xml" })
>     public class BaseTest { 
>     
>     }
>     
>       
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> 
> 因为`spring-service`在`service`层的测试中会时候到，这里也一起引入算了！
> 
> 新建`BookDaoTest.java`和`AppointmentDaoTest.java`两个dao测试文件。
> 
> BookDaoTest.java
> 
>     package com.soecode.lyf.dao;
>     
>     import java.util.List;
>     
>     import org.junit.Test;
>     import org.springframework.beans.factory.annotation.Autowired;
>     
>     import com.soecode.lyf.BaseTest;
>     import com.soecode.lyf.entity.Book;
>     
>     public class BookDaoTest extends BaseTest { 
>     
>         @Autowired
>         private BookDao bookDao;
>     
>         @Test
>         public void testQueryById() throws Exception {
>             long bookId = 1000;
>             Book book = bookDao.queryById(bookId);
>             System.out.println(book);
>         }
>     
>         @Test
>         public void testQueryAll() throws Exception {
>             List<Book> books = bookDao.queryAll(0, 4);
>             for (Book book : books) {
>                 System.out.println(book);
>             }
>         }
>     
>         @Test
>         public void testReduceNumber() throws Exception {
>             long bookId = 1000;
>             int update = bookDao.reduceNumber(bookId);
>             System.out.println("update=" + update);
>         }
>     
>     }
>       
>        
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> 
> #### BookDaoTest测试结果 ####
> 
> testQueryById   
> ![testQueryById][]
> 
> testQueryAll   
> ![testQueryAll][]
> 
> testReduceNumber   
> ![testReduceNumber][]
> 
> AppointmentDaoTest.java
> 
>     package com.soecode.lyf.dao;
>     
>     import org.junit.Test;
>     import org.springframework.beans.factory.annotation.Autowired;
>     
>     import com.soecode.lyf.BaseTest;
>     import com.soecode.lyf.entity.Appointment;
>     
>     public class AppointmentDaoTest extends BaseTest { 
>     
>         @Autowired
>         private AppointmentDao appointmentDao;
>     
>         @Test
>         public void testInsertAppointment() throws Exception {
>             long bookId = 1000;
>             long studentId = 12345678910L;
>             int insert = appointmentDao.insertAppointment(bookId, studentId);
>             System.out.println("insert=" + insert);
>         }
>     
>         @Test
>         public void testQueryByKeyWithBook() throws Exception {
>             long bookId = 1000;
>             long studentId = 12345678910L;
>             Appointment appointment = appointmentDao.queryByKeyWithBook(bookId, studentId);
>             System.out.println(appointment);
>             System.out.println(appointment.getBook());
>         }
>     
>     }
>       
>        
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> 
> #### AppointmentDaoTest测试结果 ####
> 
> testInsertAppointment   
> ![testInsertAppointment][]
> 
> testQueryByKeyWithBook   
> ![testQueryByKeyWithBook][]
> 
> --------------------
> 
> 嗯，到这里一切到很顺利~那么我们继续service层的编码吧~可能下面开始信息里比较大，大家要做好心理准备~
> 
> 首先，在写我们的业务之前，我们先定义几个预约图书操作返回码的数据字典，我们这类使用枚举类，没听过的小伙伴要好好恶补一下了（我也是最近才学到的= =）
> 
> 预约业务操作返回码说明
> 
> <table style="box-sizing: border-box; border-collapse: collapse; border-spacing: 0px; max-width: 100%; background: transparent; margin: 0px; padding: 0px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: baseline; width: 731px; font-family: &quot;microsoft yahei&quot;;"> 
>  <thead style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <th style="box-sizing: border-box; text-align: left; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">返回码</th> 
>    <th style="box-sizing: border-box; text-align: left; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">说明</th> 
>   </tr> 
>  </thead> 
>  <tbody style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">1</td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">预约成功</td> 
>   </tr> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">0</td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">库存不足</td> 
>   </tr> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">-1</td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">重复预约</td> 
>   </tr> 
>   <tr style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: baseline; background: transparent;"> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">-2</td> 
>    <td style="box-sizing: border-box; margin: 0px; padding: 8px; border: 1px solid rgb(238, 238, 238); outline: 0px; font-size: 14px; vertical-align: top; background: transparent; line-height: 20px;">系统异常</td> 
>   </tr> 
>  </tbody> 
> </table>
> 
> 新建一个包叫`enums`，在里面新建一个枚举类`AppointStateEnum.java`，用来定义预约业务的数据字典，没听懂没关系，我们直接看代码吧~是不是感觉有模有样了！
> 
> AppointStateEnum.java
> 
>     package com.soecode.lyf.enums;
>     
>     /** * 使用枚举表述常量数据字典 */
>     public enum AppointStateEnum {
>     
>         SUCCESS(1, "预约成功"), NO_NUMBER(0, "库存不足"), REPEAT_APPOINT(-1, "重复预约"), INNER_ERROR(-2, "系统异常");
>     
>         private int state;
>     
>         private String stateInfo;
>     
>         private AppointStateEnum(int state, String stateInfo) {
>             this.state = state;
>             this.stateInfo = stateInfo;
>         }
>     
>         public int getState() {
>             return state;
>         }
>     
>         public String getStateInfo() {
>             return stateInfo;
>         }
>     
>         public static AppointStateEnum stateOf(int index) {
>             for (AppointStateEnum state : values()) {
>                 if (state.getState() == index) {
>                     return state;
>                 }
>             }
>             return null;
>         }
>     
>     }
>       
>        
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> 
> --------------------
> 
> 接下来，在`dto`包下新建`AppointExecution.java`用来存储我们执行预约操作的返回结果。
> 
> AppointExecution.java
> 
>     package com.soecode.lyf.dto;
>     
>     import com.soecode.lyf.entity.Appointment;
>     import com.soecode.lyf.enums.AppointStateEnum;
>     
>     /** * 封装预约执行后结果 */
>     public class AppointExecution { 
>     
>         // 图书ID
>         private long bookId;
>     
>         // 秒杀预约结果状态
>         private int state;
>     
>         // 状态标识
>         private String stateInfo;
>     
>         // 预约成功对象
>         private Appointment appointment;
>     
>         public AppointExecution() {
>         }
>     
>         // 预约失败的构造器
>         public AppointExecution(long bookId, AppointStateEnum stateEnum) {
>             this.bookId = bookId;
>             this.state = stateEnum.getState();
>             this.stateInfo = stateEnum.getStateInfo();
>         }
>     
>         // 预约成功的构造器
>         public AppointExecution(long bookId, AppointStateEnum stateEnum, Appointment appointment) {
>             this.bookId = bookId;
>             this.state = stateEnum.getState();
>             this.stateInfo = stateEnum.getStateInfo();
>             this.appointment = appointment;
>         }
>     
>         // 省略getter和setter方法，toString方法
>     
>     }
>     
>       
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> 
> --------------------
> 
> 咱们终于可以编写业务代码了，在`service`包下新建`BookService.java`图书业务接口。
> 
> BookService.java
> 
>     package com.soecode.lyf.service;
>     
>     import java.util.List;
>     
>     import com.soecode.lyf.dto.AppointExecution;
>     import com.soecode.lyf.entity.Book;
>     
>     /** * 业务接口：站在"使用者"角度设计接口 三个方面：方法定义粒度，参数，返回类型（return 类型/异常） */
>     public interface BookService { 
>     
>         /** * 查询一本图书 * * @param bookId * @return */
>         Book getById(long bookId);
>     
>         /** * 查询所有图书 * * @return */
>         List<Book> getList();
>     
>         /** * 预约图书 * * @param bookId * @param studentId * @return */
>         AppointExecution appoint(long bookId, long studentId);
>     
>     }
>       
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> 
> 在`service.impl`包下新建`BookServiceImpl.java`使用`BookService`接口，并实现里面的方法。
> 
> BookServiceImpl
> 
>     package com.soecode.lyf.service.impl;
>     
>     import java.util.List;
>     
>     import org.slf4j.Logger;
>     import org.slf4j.LoggerFactory;
>     import org.springframework.beans.factory.annotation.Autowired;
>     import org.springframework.stereotype.Service;
>     import org.springframework.transaction.annotation.Transactional;
>     
>     import com.soecode.lyf.dao.AppointmentDao;
>     import com.soecode.lyf.dao.BookDao;
>     import com.soecode.lyf.dto.AppointExecution;
>     import com.soecode.lyf.entity.Appointment;
>     import com.soecode.lyf.entity.Book;
>     import com.soecode.lyf.enums.AppointStateEnum;
>     import com.soecode.lyf.service.BookService;
>     
>     @Service
>     public class BookServiceImpl implements BookService { 
>     
>         private Logger logger = LoggerFactory.getLogger(this.getClass());
>     
>         // 注入Service依赖
>         @Autowired
>         private BookDao bookDao;
>     
>         @Autowired
>         private AppointmentDao appointmentDao;
>     
>     
>         @Override
>         public Book getById(long bookId) {
>             return bookDao.queryById(bookId);
>         }
>     
>         @Override
>         public List<Book> getList() {
>             return bookDao.queryAll(0, 1000);
>         }
>     
>         @Override
>         @Transactional
>         /** * 使用注解控制事务方法的优点： 1.开发团队达成一致约定，明确标注事务方法的编程风格 * 2.保证事务方法的执行时间尽可能短，不要穿插其他网络操作，RPC/HTTP请求或者剥离到事务方法外部 * 3.不是所有的方法都需要事务，如只有一条修改操作，只读操作不需要事务控制 */
>         public AppointExecution appoint(long bookId, long studentId) {
>             try {
>                 // 减库存
>                 int update = bookDao.reduceNumber(bookId);
>                 if (update <= 0) {
>         // 库存不足
>                     return new AppointExecution(bookId, AppointStateEnum.NO_NUMBER);
>                 } else {
>                     // 执行预约操作
>                     int insert = appointmentDao.insertAppointment(bookId, studentId);
>                     if (insert <= 0) {
>         // 重复预约
>                         return new AppointExecution(bookId, AppointStateEnum.REPEAT_APPOINT);
>                     } else {
>         // 预约成功
>                         Appointment appointment = appointmentDao.queryByKeyWithBook(bookId, studentId);
>                         return new AppointExecution(bookId, AppointStateEnum.SUCCESS, appointment);
>                     }
>                 }
>             } catch (Exception e) {
>                 logger.error(e.getMessage(), e);
>                 // 所有编译期异常转换为运行期异常
>                 return new AppointExecution(bookId, AppointStateEnum.INNER_ERROR);
>             }
>         }
>     
>     }
>     
>       
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> 
> --------------------
> 
> 下面我们来测试一下我们的业务代码吧~因为查询图书的业务不复杂，所以这里只演示我们最重要的预约图书业务！！
> 
> BookServiceImplTest.java
> 
>     package com.soecode.lyf.service.impl;
>     
>     import static org.junit.Assert.fail;
>     
>     import org.junit.Test;
>     import org.springframework.beans.factory.annotation.Autowired;
>     
>     import com.soecode.lyf.BaseTest;
>     import com.soecode.lyf.dto.AppointExecution;
>     import com.soecode.lyf.service.BookService;
>     
>     public class BookServiceImplTest extends BaseTest { 
>     
>         @Autowired
>         private BookService bookService;
>     
>         @Test
>         public void testAppoint() throws Exception {
>             long bookId = 1001;
>             long studentId = 12345678910L;
>             AppointExecution execution = bookService.appoint(bookId, studentId);
>             System.out.println(execution);
>         }
>     
>     }
>     
>       
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> 
> #### BookServiceImplTest测试结果 ####
> 
> testAppoint   
> ![testAppoint][]
> 
> 首次执行是“预约成功”，如果再次执行的话，应该会出现“重复预约”，哈哈，我们所有的后台代码都通过单元测试啦~~是不是很开心~
> 
> --------------------
> 
> 咱们还需要在`dto`包里新建一个封装json返回结果的类`Result.java`，设计成泛型。
> 
> Result.java
> 
>     package com.soecode.lyf.dto;
>     
>     /** * 封装json对象，所有返回结果都使用它 */
>     public class Result<T> { 
>     
>         private boolean success;// 是否成功标志
>     
>         private T data;// 成功时返回的数据
>     
>         private String error;// 错误信息
>     
>         public Result() {
>         }
>     
>         // 成功时的构造器
>         public Result(boolean success, T data) {
>             this.success = success;
>             this.data = data;
>         }
>     
>         // 错误时的构造器
>         public Result(boolean success, String error) {
>             this.success = success;
>             this.error = error;
>         }
>     
>         // 省略getter和setter方法
>     }
>     
>       
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> 
> --------------------
> 
> 最后，我们写web层，也就是controller，我们在`web`包下新建`BookController.java`文件。
> 
> BookController.java
> 
>     package com.soecode.lyf.web;
>     
>     import java.util.List;
>     
>     import org.apache.ibatis.annotations.Param;
>     import org.slf4j.Logger;
>     import org.slf4j.LoggerFactory;
>     import org.springframework.beans.factory.annotation.Autowired;
>     import org.springframework.stereotype.Controller;
>     import org.springframework.ui.Model;
>     import org.springframework.web.bind.annotation.PathVariable;
>     import org.springframework.web.bind.annotation.RequestMapping;
>     import org.springframework.web.bind.annotation.RequestMethod;
>     import org.springframework.web.bind.annotation.ResponseBody;
>     
>     import com.soecode.lyf.dto.AppointExecution;
>     import com.soecode.lyf.dto.Result;
>     import com.soecode.lyf.entity.Book;
>     import com.soecode.lyf.service.BookService;
>     
>     @Controller
>     @RequestMapping("/book") // url:/模块/资源/{id}/细分 /seckill/list
>     public class BookController { 
>     
>         private Logger logger = LoggerFactory.getLogger(this.getClass());
>     
>         @Autowired
>         private BookService bookService;
>     
>         @RequestMapping(value = "/list", method = RequestMethod.GET)
>         private String list(Model model) {
>             List<Book> list = bookService.getList();
>             model.addAttribute("list", list);
>             // list.jsp + model = ModelAndView
>             return "list";// WEB-INF/jsp/"list".jsp
>         }
>     
>         // ajax json
>         @RequestMapping(value = "/{bookId}/detail", method = RequestMethod.GET)
>         @ResponseBody
>         private String detail(@PathVariable("bookId") Long bookId, Model model) {
>             if (bookId == null) {
>                 return "redirect:/book/list";
>             }
>             Book book = bookService.getById(bookId);
>             if (book == null) {
>                 return "forward:/book/list";
>             }
>             model.addAttribute("book", book);
>             return "detail";
>         }
>     
>         @RequestMapping(value = "/{bookId}/appoint", method = RequestMethod.POST, produces = {
>                 "application/json; charset=utf-8" })
>         private Result<AppointExecution> appoint(@PathVariable("bookId") Long bookId, @Param("studentId") Long studentId) {
>             if (studentId == null || studentId.equals("")) {
>                 return new Result<>(false, "学号不能为空");
>             }
>             AppointExecution execution = bookService.appoint(bookId, studentId);
>             return new Result<AppointExecution>(true, execution);
>         }
>     
>     }
>     
>       
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> 
> 因为我比较懒，所以我们就不测试controller了,好讨厌写前端，呜呜呜~
> 
> 到此，我们的SSM框架整合配置，与应用实例部分已经结束了，我把所有源码和jar包一起打包放在了我的GitHub上，需要的可以去下载，喜欢就给个star吧，这篇东西写了两个晚上也不容易啊。
> 
> 源码下载：[http://github.com/liyifeng1994/ssm][http_github.com_liyifeng1994_ssm]
> 
>   
>

[20160618002041099]: /images/20220714/9fc2dcac7dcb43b390651d4d0858f913.png
[20160618004306660]: /images/20220714/67fc58b490eb4a06b59052ba9ed81dad.png
[Link 1]: http://www.imooc.com/learn/443
[github]: https://github.com/liyifeng1994/ssm
[logback]: http://logback.qos.ch/manual/
[20160618142208354]: /images/20220714/ac1784fa6682438d83d9cc7bf59de5ca.png
[testQueryById]: http://img.bbs.csdn.net/upload/201606/18/1466255160_717902.png
[testQueryAll]: http://img.bbs.csdn.net/upload/201606/18/1466255452_743822.png
[testReduceNumber]: http://img.bbs.csdn.net/upload/201606/18/1466255505_256048.png
[testInsertAppointment]: http://img.bbs.csdn.net/upload/201606/18/1466255520_227298.png
[testQueryByKeyWithBook]: http://img.bbs.csdn.net/upload/201606/18/1466255537_831651.png
[testAppoint]: http://img.bbs.csdn.net/upload/201606/19/1466270053_292015.png
[http_github.com_liyifeng1994_ssm]: http://github.com/liyifeng1994/ssm