Mybatis - MyBatis Generator

Mybatis 提供 MGB 用来自动生成 mybatis 交互文件。包括 model、mapper接口、mapper xml 文件，可以减少工作量和出错率。

官网：http://www.mybatis.org/generator/index.html

准备：

CREATE DATABASE mytest;

CREATE TABLE t_user(
  user_id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
  user_name VARCHAR(255) NOT NULL ,
  password VARCHAR(255) NOT NULL ,
  phone VARCHAR(255) NOT NULL
) ENGINE=INNODB AUTO_INCREMENT=1000 DEFAULT CHARSET=utf8;

使用方法：maven 集成 插件：

	<build>
		<plugins>
            <!-- mybatis generator 自动生成代码插件 -->
            <plugin>
                <groupId>org.mybatis.generator</groupId>
                <artifactId>mybatis-generator-maven-plugin</artifactId>
                <version>1.3.5</version>
                <configuration>
                    <configurationFile>${basedir}/src/main/resources/generator/generatorConfig.xml</configurationFile>
                    <overwrite>true</overwrite>
                    <verbose>true</verbose>
                </configuration>
            </plugin>
		</plugins>
	</build>

其中：configurationFile 指定 MGB 的配置信息 generatorConfig.xml

<?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>
    <!-- 数据库驱动:选择你的本地硬盘上面的数据库驱动包-->
    <classPathEntry  location="D:\apache-maven-3.2.5\repository\mysql\mysql-connector-java\5.1.25\mysql-connector-java-5.1.25.jar"/>
    <context id="DB2Tables"  targetRuntime="MyBatis3">
        <commentGenerator>
            <property name="suppressDate" value="true"/>
            <!-- 是否去除自动生成的注释 true：是 ： false:否 -->
            <property name="suppressAllComments" value="true"/>
        </commentGenerator>

        <!--数据库链接URL，用户名、密码 -->
        <jdbcConnection driverClass="com.mysql.jdbc.Driver"
                        connectionURL="jdbc:mysql://127.0.0.1:3307/mytest"
                        userId="root"
                        password="root">
        </jdbcConnection>
        
        <!-- The Java Type Resolver should not force the use of BigDecimal fields - this means that integral types (Short, Integer, Long, etc.) will be substituted if possible.
        This feature is an attempt to make database DECIMAL and NUMERIC columns easier to deal with.-->
        <javaTypeResolver>
            <property name="forceBigDecimals" value="false"/>
        </javaTypeResolver>

        <!-- 生成模型的包名和位置-->
        <javaModelGenerator targetPackage="com.springboot.mybatis.demo.model" targetProject="src/main/java">
            <property name="enableSubPackages" value="true"/>
            <property name="trimStrings" value="true"/>
        </javaModelGenerator>


        <!-- 生成映射文件的包名和位置-->
        <sqlMapGenerator targetPackage="mapping" targetProject="src/main/resources">
            <property name="enableSubPackages" value="true"/>
        </sqlMapGenerator>

        <!-- 生成Mapper的包名和位置-->
        <javaClientGenerator type="XMLMAPPER" targetPackage="com.springboot.mybatis.demo.mapper" targetProject="src/main/java">
            <property name="enableSubPackages" value="true"/>
        </javaClientGenerator>

        <!-- 要生成的表 tableName是数据库中的表名或视图名 domainObjectName是实体类名-->
        <table tableName="t_user" domainObjectName="User" enableCountByExample="false" enableUpdateByExample="false" enableDeleteByExample="false" enableSelectByExample="false" selectByExampleQueryId="false"></table>
    </context>
</generatorConfiguration>

里面所需主要信息为：指定 model , mapper xml , mapper dao 路径。

运行方法：

1、命令行直接运行：mvn mybatis-generator:generate

2、IDEA 中运行方法：

点击run-Edit Configurations：

添加配置：

运行：

生成的文件：

user.java:

public class User {
    private Integer userId;

    private String userName;

    private String password;

    private String phone;

    public Integer getUserId() {
        return userId;
    }

    public void setUserId(Integer userId) {
        this.userId = userId;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName == null ? null : userName.trim();
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password == null ? null : password.trim();
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone == null ? null : phone.trim();
    }
}

UserMapper.java:

public interface UserMapper {
    int deleteByPrimaryKey(Integer userId);

    int insert(User record);

    int insertSelective(User record);

    User selectByPrimaryKey(Integer userId);

    int updateByPrimaryKeySelective(User record);

    int updateByPrimaryKey(User record);

    List<User> selectAllUser();//我自己加的
}

UserMapper.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.springboot.mybatis.demo.mapper.UserMapper">
  <resultMap id="BaseResultMap" type="com.springboot.mybatis.demo.model.User">
    <id column="user_id" jdbcType="INTEGER" property="userId" />
    <result column="user_name" jdbcType="VARCHAR" property="userName" />
    <result column="password" jdbcType="VARCHAR" property="password" />
    <result column="phone" jdbcType="VARCHAR" property="phone" />
  </resultMap>
  <sql id="Base_Column_List">
    user_id, user_name, password, phone
  </sql>

  <!-- 这个方法是我自己加的 -->
  <select id="selectAllUser" resultMap="BaseResultMap">
    select
    <include refid="Base_Column_List" />
    from t_user
  </select>

  <select id="selectByPrimaryKey" parameterType="java.lang.Integer" resultMap="BaseResultMap">
    select 
    <include refid="Base_Column_List" />
    from t_user
    where user_id = #{userId,jdbcType=INTEGER}
  </select>
  <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer">
    delete from t_user
    where user_id = #{userId,jdbcType=INTEGER}
  </delete>
  <insert id="insert" parameterType="com.springboot.mybatis.demo.model.User">
    insert into t_user (user_id, user_name, password, 
      phone)
    values (#{userId,jdbcType=INTEGER}, #{userName,jdbcType=VARCHAR}, #{password,jdbcType=VARCHAR}, 
      #{phone,jdbcType=VARCHAR})
  </insert>
  <insert id="insertSelective" parameterType="com.springboot.mybatis.demo.model.User">
    insert into t_user
    <trim prefix="(" suffix=")" suffixOverrides=",">
      <if test="userId != null">
        user_id,
      </if>
      <if test="userName != null">
        user_name,
      </if>
      <if test="password != null">
        password,
      </if>
      <if test="phone != null">
        phone,
      </if>
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides=",">
      <if test="userId != null">
        #{userId,jdbcType=INTEGER},
      </if>
      <if test="userName != null">
        #{userName,jdbcType=VARCHAR},
      </if>
      <if test="password != null">
        #{password,jdbcType=VARCHAR},
      </if>
      <if test="phone != null">
        #{phone,jdbcType=VARCHAR},
      </if>
    </trim>
  </insert>
  <update id="updateByPrimaryKeySelective" parameterType="com.springboot.mybatis.demo.model.User">
    update t_user
    <set>
      <if test="userName != null">
        user_name = #{userName,jdbcType=VARCHAR},
      </if>
      <if test="password != null">
        password = #{password,jdbcType=VARCHAR},
      </if>
      <if test="phone != null">
        phone = #{phone,jdbcType=VARCHAR},
      </if>
    </set>
    where user_id = #{userId,jdbcType=INTEGER}
  </update>
  <update id="updateByPrimaryKey" parameterType="com.springboot.mybatis.demo.model.User">
    update t_user
    set user_name = #{userName,jdbcType=VARCHAR},
      password = #{password,jdbcType=VARCHAR},
      phone = #{phone,jdbcType=VARCHAR}
    where user_id = #{userId,jdbcType=INTEGER}
  </update>
</mapper>

测试一下：

@RunWith(SpringRunner.class)
@SpringBootTest
public class UserMapperTest {

    @Autowired
    private UserMapper userMapper;

    @Test
    @Ignore
    public void queryUser() {
        //PageHelper.startPage(1, 1);
        List<User> areaList = userMapper.selectAllUser();
        assertEquals(3,areaList.size());
    }

    @Test
    public void insertUser() {
        User user = new User();
        user.setUserName("西南院");
        user.setPassword("123456");
        user.setPhone("888888");
        user.setUserId(1);
        int effectedNum = userMapper.insert(user);
        assertEquals(1,effectedNum);
    }
}

使用MGB 还可以规范代码，简洁高效。当然 复杂的SQL 还是需要手工写。