介绍

本文从零开始讲解SpringBoot整合MyBatis逆向工程及MyBatis通用Mapper的详细步骤和示例代码。MyBatis是一款优秀的ORM框架，通过逆向工程可以将关系型数据库的表结构生成对应的Java Bean，以及相关的Mapper和XML映射文件，以减少开发量。而MyBatis通用Mapper可以进一步提高开发效率，省去了大量的Mapper编写工作。SpringBoot则提供了一种快速开发、方便集成的利器，通过SpringBoot整合MyBatis逆向工程和MyBatis通用Mapper，可以快速完成项目的开发。

环境准备

JDK1.8
Maven3.0以上
IntelliJ IDEA或Eclipse
SpringBoot
MyBatis逆向工程插件generator
MyBatis通用Mapper插件mapper-helper

MyBatis逆向工程

配置逆向工程插件

pom.xml文件中增加MyBatis Generator插件（这里使用的是MySQL数据库）：

<build>
    <plugins>
        <plugin>
            <groupId>org.mybatis.generator</groupId>
            <artifactId>mybatis-generator-maven-plugin</artifactId>
            <version>1.3.2</version>
            <configuration>
                <configurationFile>src/main/resources/generator/generatorConfig.xml</configurationFile>
                <verbose>true</verbose>
                <overwrite>true</overwrite>
            </configuration>
            <dependencies>
                <dependency>
                    <groupId>mysql</groupId>
                    <artifactId>mysql-connector-java</artifactId>
                    <version>5.1.30</version>
                    <scope>runtime</scope>
                </dependency>
              </dependencies>
        </plugin>
    </plugins>
</build>

配置generator.xml

在src/main/resources/generator目录下创建generatorConfig.xml文件：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration PUBLIC
        "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
        "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
<generatorConfiguration>
  <context id="MySql" targetRuntime="MyBatis3">
    <commentGenerator>
      <property name="suppressDate" value="true"/>
      <property name="suppressAllComments" value="true"/>
    </commentGenerator>
    <jdbcConnection driverClass="com.mysql.jdbc.Driver"
        connectionURL="jdbc:mysql://localhost:3306/test?useUnicode=true&amp;characterEncoding=utf-8&amp;useSSL=false"
        userId="root"
        password="root">
    </jdbcConnection>
    <javaTypeResolver>
      <property name="forceBigDecimals" value="false"/>
    </javaTypeResolver>
    <javaModelGenerator targetPackage="com.example.demo.model" targetProject="src/main/java">
      <property name="enableSubPackages" value="true"/>
      <property name="trimStrings" value="true"/>
    </javaModelGenerator>
    <sqlMapGenerator targetPackage="mapper" targetProject="src/main/resources">
      <property name="enableSubPackages" value="true"/>
    </sqlMapGenerator>
    <javaClientGenerator targetPackage="com.example.demo.dao" targetProject="src/main/java" type="XMLMAPPER">
      <property name="enableSubPackages" value="true"/>
    </javaClientGenerator>
    <table tableName="user" domainObjectName="User"></table>
  </context>
</generatorConfiguration>

该文件的作用是配置逆向工程的相关信息，包括连接数据库的信息、生成代码的信息、生成的表和实体类等。

生成代码

在IDEA或Eclipse中打开终端，输入以下命令即可生成代码：

mvn mybatis-generator:generate

生成的代码在src/main/java和src/main/resources中。

MyBatis通用Mapper

配置通用Mapper插件

pom.xml文件中增加mapper-helper插件（这里使用的是MySQL数据库）：

<build>
    <plugins>
        <plugin>
            <groupId>org.mybatis.generator</groupId>
            <artifactId>mybatis-generator-maven-plugin</artifactId>
            <version>1.3.2</version>
            <configuration>
                <configurationFile>src/main/resources/generator/generatorConfig.xml</configurationFile>
                <verbose>true</verbose>
                <overwrite>true</overwrite>
            </configuration>
            <dependencies>
                <dependency>
                    <groupId>mysql</groupId>
                    <artifactId>mysql-connector-java</artifactId>
                    <version>5.1.30</version>
                    <scope>runtime</scope>
                </dependency>
              </dependencies>
        </plugin>
        <plugin>
            <groupId>com.github.abel533</groupId>
            <artifactId>mapper-helper-maven-plugin</artifactId>
            <version>3.0.5</version>
            <executions>
                <execution>
                    <phase>compile</phase>
                    <goals>
                        <goal>generate</goal>
                    </goals>
                    <configuration>
                        <configFile>src/main/resources/generator/generatorConfig.xml</configFile>
                        <type>MYSQL</type>
                        <extend>true</extend>
                    </configuration>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

配置MyBatis

在src/main/resources目录下创建mybatis-config.xml文件：

<?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>
    <typeAliases>
        <package name="com.example.demo.model" />
    </typeAliases>

    <mappers>
        <mapper resource="mapper/UserMapper.xml" />
    </mappers>

    <plugins>
        <plugin interceptor="com.github.abel533.mapperhelper.MapperInterceptor">
            <property name="IDENTITY" value="MYSQL"/>
        </plugin>
    </plugins>
</configuration>

该文件的作用是将实体类别名设置为包路径，将Mapper映射文件加入到配置文件中，并配置通用Mapper插件。

配置Mapper

在src/main/resources/mapper目录下创建UserMapper.xml文件，存放SQL语句：

<?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.example.demo.dao.UserMapper">

    <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer">
        select
        <include refid="Base_Column_List" />
        from user
        where id = #{id,jdbcType=INTEGER}
    </select>

    <insert id="insert" parameterType="com.example.demo.model.User">
        insert into user (name, age) values (#{name,jdbcType=VARCHAR}, #{age,jdbcType=INTEGER});
    </insert>

    <update id="updateByPrimaryKey" parameterType="com.example.demo.model.User">
        update user
        set name = #{name,jdbcType=VARCHAR},
            age = #{age,jdbcType=INTEGER}
        where id = #{id,jdbcType=INTEGER}
    </update>

    <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer">
        delete from user where id = #{id,jdbcType=INTEGER}
    </delete>

</mapper>

使用通用Mapper

在src/main/java/com/example/demo/service/impl/UserServiceImpl.java中，注入UserMapper:

@Service
public class UserServiceImpl implements UserService {

    //注入Mapper
    @Autowired
    private UserMapper userMapper;

    @Override
    public User getUserById(int id) {
        return this.userMapper.selectByPrimaryKey(id);
    }

    @Override
    public int saveUser(User user) {
        return this.userMapper.insert(user);
    }

    @Override
    public int updateUser(User user) {
        return this.userMapper.updateByPrimaryKey(user);
    }

    @Override
    public int deleteUser(int id) {
        return this.userMapper.deleteByPrimaryKey(id);
    }
}

完成以上步骤后，即完成了整合MyBatis逆向工程和MyBatis通用Mapper的工作。

示例

这里提供两个示例：

查询用户

访问地址：http://localhost:8080/user/1

UserController.java：

@RestController
@RequestMapping("/user")
public class UserController {

    @Autowired
    private UserService userService;

    @RequestMapping("/{id}")
    public User getUserById(@PathVariable("id") int id) {
        return this.userService.getUserById(id);
    }
}

添加用户

访问地址：http://localhost:8080/user