mybatis学习(4) - SpringBoot中整合mybatis

红太狼 2024-05-25 17:37 63阅读 0赞

前几篇已经简单的学习了mybatis及mbg的简单使用，从此篇文章开始介绍一下mybatis与spring之间的整合及使用，官方的使用文档如下：[https://mybatis.org/spring-boot-starter/mybatis-spring-boot-autoconfigure/index.html][https_mybatis.org_spring-boot-starter_mybatis-spring-boot-autoconfigure_index.html]，本文结合官方文档，进行简单整合使用。

## 创建spring-myBatis项目 ##

打开idea工具，创建[spring initializr][]项目，pom.xml配置文件如下:

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.7.5</version>
            <relativePath/> 
        </parent>
        <groupId>io.hxjstudy</groupId>
        <artifactId>java-mybatis2-spring-tiny</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <name>java-mybatis2-spring-tiny</name>
        <description>java-mybatis2-spring-tiny</description>
        <properties>
            <java.version>11</java.version>
        </properties>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            <dependency>
                <groupId>org.mybatis.spring.boot</groupId>
                <artifactId>mybatis-spring-boot-starter</artifactId>
                <version>2.2.2</version>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-devtools</artifactId>
                <scope>runtime</scope>
                <optional>true</optional>
            </dependency>
            <dependency>
                <groupId>com.mysql</groupId>
                <artifactId>mysql-connector-j</artifactId>
                <scope>runtime</scope>
            </dependency>
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <optional>true</optional>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
        </dependencies>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                    <configuration>
                        <excludes>
                            <exclude>
                                <groupId>org.projectlombok</groupId>
                                <artifactId>lombok</artifactId>
                            </exclude>
                        </excludes>
                    </configuration>
                </plugin>
            </plugins>
        </build>
    </project>

直接启动项目，报错如下：

***************************
    APPLICATION FAILED TO START
    ***************************
    
    Description:
    
    Failed to configure a DataSource: 'url' attribute is not specified and no embedded datasource could be configured.
    
    Reason: Failed to determine a suitable driver class
    
    
    Action:
    
    Consider the following:
    	If you want an embedded database (H2, HSQL or Derby), please put it on the classpath.
    	If you have database settings to be loaded from a particular profile you may need to activate it (no profiles are currently active).
    
    
    Process finished with exit code 0

为什么报错，由于我们集成了mybatis项目，但是我们并没有给到他数据源的配置，所以系统就告诉我们，你没配置数据源啊，我启动不了了。虽然可以使用排除启动类的方式：

@SpringBootApplication(exclude = {
        DataSourceAutoConfiguration.class})

来消除错误。

## 配置Springboot应用文件 ##

在application.properties文件中添加数据源信息，如下：

# 数据库配置
    spring.datasource.url = jdbc:mysql://localhost:3388/db_ddyx?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai
    spring.datasource.username = root
    spring.datasource.password = root
    
    # 查看查询日志
    mybatis.configuration.log-impl = org.apache.ibatis.logging.stdout.StdOutImpl

现在可以正常启动，但是我们还未使用mybatis框架，接下来开始使用框架来查询数据。

## 编写应用代码(Mapper/Model/Controller) ##

我们使用最简单的查询Mapper接口，查询语句直接使用注解的方式实现如下：

package io.hxjstudy.javamybatis2springtiny.mapper;
    
    import io.hxjstudy.javamybatis2springtiny.model.UserInfo;
    import org.apache.ibatis.annotations.Mapper;
    import org.apache.ibatis.annotations.Select;
    
    @Mapper
    public interface UserMapper {
        
        @Select("SELECT * FROM g2_user limit 1")
        UserInfo findOne();
    }

创建一个返回model类，UserInfo，代码如下：

package io.hxjstudy.javamybatis2springtiny.model;
    
    import lombok.Data;
    
    @Data
    public class UserInfo {
        
        //protected String
        protected String uid;
        protected String unick;
    }

代码中我们使用了lombok插件，具体的lombok使用，请参考：[https://projectlombok.org/][https_projectlombok.org]。接下来创建一个最简单的controller来访问:

package io.hxjstudy.javamybatis2springtiny.controller;
    
    import io.hxjstudy.javamybatis2springtiny.mapper.UserMapper;
    import io.hxjstudy.javamybatis2springtiny.model.UserInfo;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    import org.springframework.web.bind.annotation.ResponseBody;
    
    @Controller
    @RequestMapping("/user")
    public class UserController {
        
        @Autowired
        private UserMapper userMapper;
    
        @RequestMapping(value = "get_one", method = RequestMethod.GET)
        @ResponseBody
        public UserInfo getOne(){
        
            UserInfo one = userMapper.findOne();
            System.out.println(one);
            return one;
        }
    }

从上面可以看出，我们使用@autowired自动注入userMapper，当然实际生产中一般会有service层来进行更复杂的逻辑处理，此处为了方便使用，简单分层。

## 启动应用并访问 ##

点击应用启动：

2022-11-04 18:10:36.087  INFO 15757 --- [  restartedMain] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1215 ms
    Logging initialized using 'class org.apache.ibatis.logging.stdout.StdOutImpl' adapter.
    Property 'mapperLocations' was not specified.
    2022-11-04 18:10:36.549  INFO 15757 --- [  restartedMain] o.s.b.d.a.OptionalLiveReloadServer       : LiveReload server is running on port 35729
    2022-11-04 18:10:36.575  INFO 15757 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
    2022-11-04 18:10:36.585  INFO 15757 --- [  restartedMain] i.h.j.JavaMybatis2SpringTinyApplication  : Started JavaMybatis2SpringTinyApplication in 2.299 seconds (JVM running for 3.075)

访问路径：http://localhost:8080/user/get\_one，控制台输出如下：

Creating a new SqlSession
    SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@67fea111] was not registered for synchronization because synchronization is not active
    2022-11-04 18:19:17.818  INFO 15757 --- [nio-8080-exec-1] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Starting...
    2022-11-04 18:19:18.161  INFO 15757 --- [nio-8080-exec-1] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Start completed.
    JDBC Connection [HikariProxyConnection@1542062776 wrapping com.mysql.cj.jdbc.ConnectionImpl@18ed7b11] will not be managed by Spring
    ==>  Preparing: SELECT * FROM g2_user limit 1
    ==> Parameters: 
    <==    Columns: uid, unick
    <==        Row: 10010323, 152****2082
    <==      Total: 1
    Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@67fea111]
    UserInfo(uid=10010323, unick=152****2082)

界面返回数据：

{
        "uid":"10010323","unick":"152****2082"}

至此基于org.mybatis.spring.boot整合mybatis的基本使用已实现，实际生产中我们都会使用xml映射文件查询，下面继续学习如何使用映射文件查询。

## spring中mybatis的配置 ##

在官网的配置说明中：[https://mybatis.org/spring-boot-starter/mybatis-spring-boot-autoconfigure/index.html][https_mybatis.org_spring-boot-starter_mybatis-spring-boot-autoconfigure_index.html]，有关于mybatis的详细配置说明：

<table> 
 <thead> 
  <tr> 
   <th>配置</th> 
   <th>说明</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>config-location</td> 
   <td>Mybatis配置文件的地址</td> 
  </tr> 
  <tr> 
   <td>check-config-location</td> 
   <td>是否检查配置文件地址 true or false</td> 
  </tr> 
  <tr> 
   <td>mapper-locations</td> 
   <td>mapper映射xml文件地址</td> 
  </tr> 
  <tr> 
   <td>type-aliases-package</td> 
   <td>搜索别名的包，通过,; \t\n”等字符作为分界符</td> 
  </tr> 
  <tr> 
   <td>type-aliases-super-type</td> 
   <td>aliases类的父类类型</td> 
  </tr> 
  <tr> 
   <td>type-handlers-package</td> 
   <td>类型转换器的包名</td> 
  </tr> 
  <tr> 
   <td>executor-type</td> 
   <td>执行的模式：SIMPLE(默认), REUSE, BATCH</td> 
  </tr> 
  <tr> 
   <td>default-scripting-language-driver</td> 
   <td>默认脚本语言驱动程序类</td> 
  </tr> 
  <tr> 
   <td>configuration-properties</td> 
   <td>配置的外部属性</td> 
  </tr> 
  <tr> 
   <td>lazy-initialization</td> 
   <td>是否启用延迟初始化</td> 
  </tr> 
  <tr> 
   <td>mapper-default-scope</td> 
   <td>被auto-configure扫描的mapper bean的默认范围</td> 
  </tr> 
  <tr> 
   <td>inject-sql-session-on-mapper-scan</td> 
   <td>是否注入一个SqlSessionTemplate或SqlSessionFactorybean</td> 
  </tr> 
  <tr> 
   <td>configuration.*</td> 
   <td>MyBatis Core配置，与config-location不能同时使用</td> 
  </tr> 
  <tr> 
   <td>scripting-language-driver.thymeleaf.*</td> 
   <td>MyBatis Thymeleaf 提供的ThymeleafLanguageDriverConfig bean 的属性键</td> 
  </tr> 
  <tr> 
   <td>scripting-language-driver.freemarker.*</td> 
   <td>MyBatis FreeMarker 提供的FreeMarkerLanguageDriverConfig bean 的属性键</td> 
  </tr> 
  <tr> 
   <td>scripting-language-driver.velocity.*</td> 
   <td>MyBatis Velocity 提供的VelocityLanguageDriverConfig bean 的属性键</td> 
  </tr> 
 </tbody> 
</table>

## 官方参考sample ##

更详细的参考，可以查看官方提供各种场景例子：[https://github.com/mybatis/spring-boot-starter][https_github.com_mybatis_spring-boot-starter]

同样，放上学习代码地址：[https://github.com/redrockfinch/java-mybatis2-spring-tiny][https_github.com_redrockfinch_java-mybatis2-spring-tiny]

[https_mybatis.org_spring-boot-starter_mybatis-spring-boot-autoconfigure_index.html]: https://mybatis.org/spring-boot-starter/mybatis-spring-boot-autoconfigure/index.html
[spring initializr]: https://start.spring.io/
[https_projectlombok.org]: https://projectlombok.org/
[https_github.com_mybatis_spring-boot-starter]: https://github.com/mybatis/spring-boot-starter
[https_github.com_redrockfinch_java-mybatis2-spring-tiny]: https://github.com/redrockfinch/java-mybatis2-spring-tiny