1 在pom.xml中新增org.mybatis.generator外掛

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <plugin
 
>
                <groupId>org.mybatis.generator</groupId>
                <artifactId>mybatis-generator-maven-plugin</artifactId>
                <version>1.3.2</version>

            </plugin>
        </plugins>
    </build>

2 新增generator執行選項

在Command line中新增如下程式碼

mybatis-generator:generate -e

3 在resources下建立generatorConfig.xml 內容如下

<?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>
    <!-- 資料庫驅動:選擇你的本地硬碟上面的資料庫驅動包-->
    <classPathEntry  location="D:\woooooork\jar\mysqlconnnect\mysql-connector-java-5.1.44.jar"/>
    <context id="DB2Tables"  targetRuntime="MyBatis3">
        <commentGenerator>
            <property name="suppressDate" value="true"/>
            <!-- 是否去除自動生成的註釋 true：是 ： false:否 -->
            <property name="suppressAllComments" value="true"/>
        </commentGenerator>
        <!--資料庫連結URL，使用者名稱、密碼 -->
        <jdbcConnection driverClass="com.mysql.jdbc.Driver" connectionURL="jdbc:mysql://localhost:3306/test?useUnicode=true" userId="root" password="123456">
        </jdbcConnection>
        <javaTypeResolver>
            <property name="forceBigDecimals" value="false"/>
        </javaTypeResolver>
        <!-- 生成模型的包名和位置-->
        <javaModelGenerator targetPackage="main.java.com.model" targetProject="src">
            <property name="enableSubPackages" value="true"/>
            <property name="trimStrings" value="true"/>
        </javaModelGenerator>
        <!-- 生成對映檔案的包名和位置-->
        <sqlMapGenerator targetPackage="main.resources.mapper" targetProject="src">
            <property name="enableSubPackages" value="true"/>
        </sqlMapGenerator>
        <!-- 生成DAO的包名和位置-->
        <javaClientGenerator type="XMLMAPPER" targetPackage="main.java.com.mapper" targetProject="src">
       <property name="enableSubPackages" value="true"/>
        </javaClientGenerator>
        <!-- 要生成的表 tableName是資料庫中的表名或檢視名 domainObjectName是實體類名-->
        <table tableName="t_user" domainObjectName="User" enableCountByExample="false" enableUpdateByExample="false" enableDeleteByExample="false" enableSelectByExample="false" selectByExampleQueryId="false"></table>
    </context>
</generatorConfiguration>

細節根據註釋修改，繫結到資料的表後，執行generator後就可以啦！

4 自動生成的xml檔案結構如下

<?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" >

<!--對應該實體類的結果集-->
<mapper namespace="com.mapper.UserMapper" >
  <resultMap id="BaseResultMap" type="com.model.User" >
    <id column="user_id" property="userId" jdbcType="INTEGER" />
    <result column="user_name" property="userName" jdbcType="VARCHAR" />
    <result column="password" property="password" jdbcType="VARCHAR" />
    <result column="phone" property="phone" jdbcType="VARCHAR" />
  </resultMap>
      <!-- 該實體類的物件 可以用這種形式，在sql展示：                <include refid="Base_Column_List" />-->  
  <sql id="Base_Column_List" >
    user_id, user_name, password, phone
  </sql>
  <!--通過主鍵查詢-->
  <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
    select 
    <include refid="Base_Column_List" />
    from t_user
    where user_id = #{userId,jdbcType=INTEGER}
  </select>
  <!--通過主鍵刪除-->
  <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >
    delete from t_user
    where user_id = #{userId,jdbcType=INTEGER}
  </delete>
  <!--插入-->
  <insert id="insert" parameterType="com.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.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.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.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>

  <!-- 自己書寫的查詢語句-->
  <select id="getUser" parameterType="String" resultType="com.model.User" >
    SELECT * FROM t_user WHERE username = #{userName,jdbcType=VARCHAR}
  </select>
<!-- 在UserMapper介面中定義List<User> 返回型別的方法，就該方法就返回物件的集合了-->
  <select id="getUserByPhone" parameterType="String" resultMap="BaseResultMap">
      SELECT
      <include refid="Base_Column_List"/>
    FROM t_user where phone= #{phone,jdbcType=VARCHAR}
  </select>
</mapper>