spring-06 springmvc设计思想与体系结构

「爱情、让人受尽委屈。」 2022-03-16 02:58 106阅读 0赞

### 文章目录 ###

*  1.servlet 与jsp 执行过程
 *  2.spring mvc 执行
 *   *  2.1 spring mvc 执行流程
     *  2.2 spring mvc 体系结构
     *  2.3 实现简单spring mvc
     *   *  2.3.1 项目依赖
         *  2.3.2 web.xml
         *  2.3.3 spring-mvc.xml
         *  2.3.4 创建controller
         *  2.3.5 运行jeety
     *  2.4 体系结构UML
 *  3.mvc 执行流程解析
 *   *  3.1 mvc 各组件执行流程
     *  3.2 HandlerMapping 详解
     *   *  3.2.1 HandlerMapping 接口方法
         *  3.2.2 HandlerMapping 接口结构
         *   *  3.2.2.1 BeanNameUrlHandlerMapping 使用(4.1 以后不支持)
     *  3.3 HandlerAdapter详解
     *   *  3.3.1 HandlerAdapter 接口方法
         *  3.3.2 HandlerAdapter 接口结构图
         *  3.3.3 基于Servlet处理SimpleServletHandlerAdapter(4.1 以后不支持)
     *  3.4 ViewResolver 与View 详解
     *  3.5 HandlerExceptionResolver详解
     *   *  3.5.1 使用
     *  3.6 HandlerInterceptor 详解
     *   *  3.6.1 演示
 *  4.注解配置
 *   *  4.1 实现
     *  4.2 为什么基于 配置就能实现mvc 的整个配置了，之前所提到的 handlerMapping 、与handlerAdapter 组件都不适用了？

# 1.servlet 与jsp 执行过程 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMxNDYzOTk5_size_16_color_FFFFFF_t_70]  
**流程说明：**

1.  请求Servlet
2.  处理业务逻辑
3.  设置业务Model
4.  forward jsp Servlet
5.  jsp Servlet 解析封装html 返回

# 2.spring mvc 执行 #

> spring mvc本质上还是在使用Servlet处理，并在其基础上进行了封装简化了开发流程，提高易用性、并使用程序逻辑结构变得更清晰

*  基于注解的URL映谢
 *  http表单参数转换
 *  全局统一异常处理
 *  拦截器的实现

## 2.1 spring mvc 执行流程 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMxNDYzOTk5_size_16_color_FFFFFF_t_70 1]

## 2.2 spring mvc 体系结构 ##

*  HandlerMapping:  
    url与控制器的映谢
 *  HandlerAdapter:  
    控制器执行适配器
 *  ViewResolver:  
    视图仓库
 *  view:  
    具体解析视图
 *  HandlerExceptionResolver:  
    异常捕捕捉器
 *  HandlerInterceptor:  
    拦截器

## 2.3 实现简单spring mvc ##

### 2.3.1 项目依赖 ###

<?xml version="1.0" encoding="UTF-8"?>
    <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/xsd/maven-4.0.0.xsd">
        <parent>
            <artifactId>spring-study</artifactId>
            <groupId>com.myx</groupId>
            <version>1.0-SNAPSHOT</version>
        </parent>
        <modelVersion>4.0.0</modelVersion>
        <packaging>jar</packaging>
        <artifactId>spring-mvc</artifactId>
        <dependencies>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-webmvc</artifactId>
                <version>${spring.version}</version>
            </dependency>
            <dependency>
                <groupId>javax.servlet</groupId>
                <artifactId>javax.servlet-api</artifactId>
                <version>3.1.0</version>
            </dependency>
            <dependency>
                <groupId>javax.servlet</groupId>
                <artifactId>jstl</artifactId>
                <version>1.2</version>
            </dependency>
            <dependency>
                <groupId>taglibs</groupId>
                <artifactId>standard</artifactId>
                <version>1.1.2</version>
            </dependency>
        </dependencies>
        <build>
            <plugins>
                <plugin>
                    <groupId>org.mortbay.jetty</groupId>
                    <artifactId>jetty-maven-plugin</artifactId>
                    <version>7.4.5.v20110725</version>
                    <configuration>
                        <webApp>
                            <contextPath>/</contextPath>
                        </webApp>
                        <scanIntervalSeconds>3</scanIntervalSeconds>
                        <scanTargetPatterns>
                            <scanTargetPattern>
                                <directory>src/main/webapp</directory>
                                <includes>
                                    <include>**/*.xml</include>
                                </includes>
                            </scanTargetPattern>
                        </scanTargetPatterns>
                        <connectors>
                            <connector implementation="org.eclipse.jetty.server.nio.SelectChannelConnector">
                                <port>8081</port>
                                <maxIdleTime>400000</maxIdleTime>
                            </connector>
                        </connectors>
                    </configuration>
                </plugin>
            </plugins>
        </build>
    </project>

### 2.3.2 web.xml ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMxNDYzOTk5_size_16_color_FFFFFF_t_70 2]

<?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee"
             xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
             id="WebApp_ID" version="3.0">
        
        <display-name>spring-mvc</display-name>
        <servlet>
            <servlet-name>dispatcherServlet</servlet-name>
            <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
            <init-param>
                <param-name>contextConfigLocation</param-name>
                <param-value>
                    classpath:/spring-mvc.xml
                </param-value>
            </init-param>
        </servlet>
        <servlet-mapping>
            <servlet-name>dispatcherServlet</servlet-name>
            <url-pattern>/</url-pattern>
        </servlet-mapping>
    
        <welcome-file-list>
            <welcome-file>/index.html</welcome-file>
        </welcome-file-list>
    
    </web-app>

### 2.3.3 spring-mvc.xml ###

<?xml version="1.0" encoding="GBK"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans.xsd">
    
        
        <bean id="simpleController" class="com.myx.spring.controller.SimpleController"></bean>
    
        
        <bean class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
            <property name="urlMap">
                <props>
                    <prop key="/user.do">simpleController</prop>
                </props>
            </property>
        </bean>
    
        
        <bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"></bean>
    
        
        <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
            <property name="prefix" value="/WEB-INF/page/"/>
            <property name="suffix" value=".jsp"/>
            <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
        </bean>
    </beans>

### 2.3.4 创建controller ###

import org.springframework.web.servlet.ModelAndView;
    import org.springframework.web.servlet.mvc.Controller;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    /**
     * 描述:简单路由映射实现mvc
     * @author: myx
     * @date: 2019/1/14
     * Copyright © 2018-hotpot. All rights reserved.
     */
    public class SimpleController implements Controller {
        @Override
        public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
            ModelAndView mv = new ModelAndView("userView");
            mv.addObject("name", "myx is good man");
            return mv;
        }
    }

### 2.3.5 运行jeety ###

![在这里插入图片描述][20190226105007509.png]  
![在这里插入图片描述][20190226105015420.png]

## 2.4 体系结构UML ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMxNDYzOTk5_size_16_color_FFFFFF_t_70 3]

# 3.mvc 执行流程解析 #

## 3.1 mvc 各组件执行流程 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMxNDYzOTk5_size_16_color_FFFFFF_t_70 4]

## 3.2 HandlerMapping 详解 ##

> 其为mvc 中url路径与Control对像的映射，DispatcherServlet 就是基于此组件来寻找对应的Control，如果找不到就会报Not Found mapping 的异常。

### 3.2.1 HandlerMapping 接口方法 ###

![在这里插入图片描述][20190226105116779.png]

### 3.2.2 HandlerMapping 接口结构 ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMxNDYzOTk5_size_16_color_FFFFFF_t_70 5]

目前主流的三种mapping:

*  BeanNameUrlHandlerMapping: 基于ioc name 中已 “/” 开头的Bean时行 注册至映谢.
 *  SimpleUrlHandlerMapping：基于手动配置 url 与control 映谢
 *  RequestMappingHandlerMapping：基于@RequestMapping注解配置对应映谢

#### 3.2.2.1 BeanNameUrlHandlerMapping 使用(4.1 以后不支持) ####

<bean id="/bean.do" class="com.myx.spring.controller.BeanNameController"></bean>
    
    import org.springframework.web.HttpRequestHandler;
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    
    /**
     * 描述:BeanNameUrlHandlerMapping 测试
     * @author: myx
     * @date: 2019/1/14
     * Copyright © 2018-hotpot. All rights reserved.
     */
    public class BeanNameController implements HttpRequestHandler {
        @Override
        public void handleRequest(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
            response.getWriter().println("myx is good man");
        }
    }

## 3.3 HandlerAdapter详解 ##

> 这里spring mvc 采用适配器模式来适配调用指定Handler，根据Handler的不同种类采用不同的Adapter,其Handler与 HandlerAdapter 对应关系如下:

<table> 
 <thead> 
  <tr> 
   <th>Handler类别</th> 
   <th>对应适配器</th> 
   <th>描述</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>Controller</td> 
   <td>SimpleControllerHandlerAdapter</td> 
   <td>标准控制器，返回ModelAndView</td> 
  </tr> 
  <tr> 
   <td>HttpRequestHandler</td> 
   <td>HttpRequestHandlerAdapter</td> 
   <td>业务自行处理 请求，不需要通过modelAndView 转到视图</td> 
  </tr> 
  <tr> 
   <td>Servlet</td> 
   <td>SimpleServletHandlerAdapter</td> 
   <td>基于标准的servlet 处理</td> 
  </tr> 
  <tr> 
   <td>HandlerMethod</td> 
   <td>RequestMappingHandlerAdapter</td> 
   <td>基于@requestMapping对应方法处理</td> 
  </tr> 
 </tbody> 
</table>

### 3.3.1 HandlerAdapter 接口方法 ###

![在这里插入图片描述][20190226105137444.png]

### 3.3.2 HandlerAdapter 接口结构图 ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMxNDYzOTk5_size_16_color_FFFFFF_t_70 6]

### 3.3.3 基于Servlet处理SimpleServletHandlerAdapter(4.1 以后不支持) ###

<bean id="/hello.do" class="com.myx.spring.controller.HelloServlet"/>
    
    
    <bean class="org.springframework.web.servlet.handler.SimpleServletHandlerAdapter"/>
    
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    
    public class HelloServlet extends HttpServlet {
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
            resp.getWriter().println("hello luban ");
        }
    }

## 3.4 ViewResolver 与View 详解 ##

> 找到应的Adapter 之后就会基于适配器调用业务处理，处理完之后业务方会返回一个ModelAndView ，在去查找对应的视图进行处理。其在org.springframework.web.servlet.DispatcherServlet\#resolveViewName() 中遍历 viewResolvers 列表查找，如果找不到就会报一个 Could not resolve view with name 异常。  
> ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMxNDYzOTk5_size_16_color_FFFFFF_t_70 7]

在下一步就是基于ViewResolver.resolveViewName() 获取对应View来解析生成Html并返回 。对应VIEW结构如下：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMxNDYzOTk5_size_16_color_FFFFFF_t_70 8]  
至此整个正向流程就已经走完了，如果此时程序处理异常 MVC 该如何处理呢？

## 3.5 HandlerExceptionResolver详解 ##

> 该组件用于指示 当出现异常时 mvc 该如何处理。 dispatcherServlet 会调用org.springframework.web.servlet.DispatcherServlet\#processHandlerException() 方法，遍历 handlerExceptionResolvers 处理异常，处理完成之后返回errorView 跳转到异常视图。

### 3.5.1 使用 ###

<bean class="com.myx.spring.controller.SimpleExceptionHandle"/>
    
    
    import org.springframework.web.servlet.HandlerExceptionResolver;
    import org.springframework.web.servlet.ModelAndView;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    /**
     * 描述:异常
     * @author: myx
     * @date: 2019/1/14
     * Copyright © 2018-hotpot. All rights reserved.
     */
    public class SimpleExceptionHandle implements HandlerExceptionResolver {
        @Override
        public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {
            return new ModelAndView("error");
        }
    }

## 3.6 HandlerInterceptor 详解 ##

> 除了上述组件之外 spring 中还引入了 我Interceptor 拦截器 机制，类似于Filter。

### 3.6.1 演示 ###

<bean class="com.myx.spring.controller.SimpleHandlerInterceptor"></bean>
    
    import org.springframework.web.servlet.HandlerInterceptor;
    import org.springframework.web.servlet.ModelAndView;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    /**
     * 描述:拦截器
     * @author: myx
     * @date: 2019/1/14
     * Copyright © 2018-hotpot. All rights reserved.
     */
    public class SimpleHandlerInterceptor implements HandlerInterceptor {
        @Override
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
            System.out.println("preHandle");
            return true;
        }
    
        @Override
        public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
            System.out.println("postHandle");
        }
    
        @Override
        public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
            System.out.println("afterCompletion");
        }
    }

其实现机制是基于 HandlerExecutionChain 分别在 doDispatch 方法中执行以下方法：

*  preHandle ：业务处理前执行
 *  postHandle：业务处理后（异常则不执行）
 *  afterCompletion：视图处理后

具体逻辑源码参见：org.springframework.web.servlet.DispatcherServlet\#doDispatch 方法。

# 4.注解配置 #

## 4.1 实现 ##

<?xml version="1.0" encoding="GBK"?>
    <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.xsd">
    
        <context:component-scan base-package="com.myx.spring.controller" />
        
        <mvc:annotation-driven/>
        
        <bean  class="org.springframework.web.servlet.view.InternalResourceViewResolver">
            <property name="prefix" value="/WEB-INF/page/" />
            <property name="suffix" value=".jsp" />
            <property name="viewClass" value="org.springframework.web.servlet.view.JstlView" />
        </bean>
    </beans>

import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.servlet.ModelAndView;
    
    /**
     * 描述:注解实现
     * @author: myx
     * @date: 2019/1/14
     * Copyright © 2018-hotpot. All rights reserved.
     */
    @Controller
    public class SimpleController{
        /**
         * 注解方法
         * @return
         */
        @RequestMapping("/hello.do")
        public ModelAndView hello() {
            ModelAndView mv = new ModelAndView("userView");
            mv.addObject("name", "myx 注解");
            return mv;
        }
    }

![在这里插入图片描述][20190226105224487.png]

## 4.2 为什么基于 mvc:annotation-driven/ 配置就能实现mvc 的整个配置了，之前所提到的 handlerMapping 、与handlerAdapter 组件都不适用了？ ##

只要查看以类的源就可以知晓其中原因：

*  认识 NamespaceHandler 接口
 *  查看 MvcNamespaceHandler
 *  查看AnnotationDrivenBeanDefinitionParser

结论：  
在<mvc:annotation-driven /> 对应的解析器，自动向ioc 里面注册了两个BeanDefinition。分别是：RequestMappingHandlerMapping与BeanNameUrlHandlerMapping

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[20190226105007509.png]: /images/20220316/b903b155e2d942d5b0188ad0d96242bb.png
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[20190226105224487.png]: /images/20220316/b64d1e967a784baa99055b08b0b83e35.png