MyBatis

MyBatis Generator：

• 简称MBG，是一个专门为MyBatis框架使用者定制的代码生成器，可以快速的根据表生成对应的映射文件，接口，以及bean类。支持基本的增删改查，以及QBC风格的条件查询。但是表连接、存储过程等这些复杂sql的定义需要我们手工编写
• 官方文档地址
  http://www.mybatis.org/generator/
• 官方工程地址
  https://github.com/mybatis/generator/releases

1.mbg配置文件编写

<?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="DB2Tables" targetRuntime="MyBatis3">
    <!--如和连接数据库-->
    <jdbcConnection driverClass="com.mysql.cj.jdbc.Driver"
      connectionURL="jdbc:mysql://localhost:4040/db_mybatis?serverTimezone = GMT"
      userId="root"
      password="123">
    </jdbcConnection>

    <javaTypeResolver>
      <property name="forceBigDecimals" value="false"/>
    </javaTypeResolver>

    <!--
      javaModelGenerator：指定javaBean生成策略
          - targetPackage="test.model":  目标包名
          - targetProject="MBGTestProjectsrc"  目标工程
    -->
    <javaModelGenerator targetPackage="com.tangge.bean" targetProject=".src">
      <property name="enableSubPackages" value="true"/>
      <property name="trimStrings" value="true"/>
    </javaModelGenerator>

    <!--
      sqlMapGenerator： sql映射XML生成策略
          - targetPackage="test.xml"：
          - targetProject="MBGTestProjectsrc"：
    -->
    <sqlMapGenerator targetPackage="tangge.mapper" targetProject=".src">
      <property name="enableSubPackages" value="true"/>
    </sqlMapGenerator>

    <!--
      javaClientGenerator：指定的mapper接口生成策略（Java客户端生成器的属性，Java客户端生成器构建Java接口和类。）
          - type="XMLMAPPER"：
              - XMLMAPPER	生成的对象将是MyBatis 3.x映射器基础结构的Java接口。接口将依赖于生成的XML映射器文件。
              - MIXEDMAPPER	接口将基于注释和XML的混合。将使用注释将在简单注释工作的地方使用。
                此客户端不会生成和Sql Provider，因此所有复杂的动态SQL都将以XML格式生成。
              - ANNOTATEDMAPPER	接口将基于注释和MyBatis 3.x SqlProviders。不会生成XML映射器文件。
          - targetPackage="test.dao"： 目标包名
          - targetProject=".src"：  目标工程
    -->
    <javaClientGenerator type="XMLMAPPER" targetPackage="com.tangge.dao"
      targetProject=".src">
      <property name="enableSubPackages" value="true"/>
    </javaClientGenerator>


    <!--<table schema="db_mybatis" tableName="tbl_employee" domainObjectName="Customer">-->
      <!--<property name="useActualColumnNames" value="true"/>-->
      <!--<generatedKey column="ID" sqlStatement="DB2" identity="true"/>-->
      <!--<columnOverride column="DATE_FIELD" property="startDate"/>-->
      <!--<ignoreColumn column="FRED"/>-->
      <!--<columnOverride column="LONG_VARCHAR_FIELD" jdbcType="VARCHAR"/>-->
    <!--</table>-->
    <!--
      table：表生成策略
          - tableName（必须）：表名
          - domainObjectName（选填）：生成类的名字
    -->
    <table schema="db_mybatis" tableName="tbl_employee" domainObjectName="Employee">
    </table>
    <table schema="db_mybatis" tableName="tbl_dept" domainObjectName="Department">
    </table>

  </context>
</generatorConfiguration>

1.1 如果不想生成Example类文件

table里面就关闭掉 enable** = "false"。

 <table tableName="tbl_employee" domainObjectName="Employee" enableCountByExample="false"
      enableDeleteByExample="false"  enableSelectByExample="false" enableSelectByPrimaryKey="true"
    enableUpdateByPrimaryKey="true" enableDeleteByPrimaryKey="true" selectByExampleQueryId="false"
      enableUpdateByExample="false">
    </table>
    <table  tableName="tbl_dept" domainObjectName="Department" enableCountByExample="false"
      enableDeleteByExample="false" enableUpdateByExample="false" enableSelectByExample="false"
      selectByExampleQueryId="false" enableSelectByPrimaryKey="true" enableUpdateByPrimaryKey="true"
      enableDeleteByPrimaryKey="true">
    </table>

2.mbg逆向生成

 @Test
    public void test()
            throws IOException, XMLParserException, InvalidConfigurationException, SQLException, InterruptedException {
        List<String> warnings = new ArrayList<String>();
        boolean overwrite = true;
        File configFile = new File("mbg.xml");
        ConfigurationParser cp = new ConfigurationParser(warnings);
        Configuration config = cp.parseConfiguration(configFile);
        DefaultShellCallback callback = new DefaultShellCallback(overwrite);
        MyBatisGenerator myBatisGenerator = new MyBatisGenerator(config, callback, warnings);
        myBatisGenerator.generate(null);
    }

下面看看 生成的mapper.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.tangge.dao.EmployeeMapper">
  <resultMap id="BaseResultMap" type="com.tangge.bean.Employee">
    <!--
      WARNING - @mbg.generated
      This element is automatically generated by MyBatis Generator, do not modify.
      This element was generated on Mon Sep 03 10:51:01 CST 2018.
    -->
    <id column="id" jdbcType="INTEGER" property="id" />
    <result column="last_name" jdbcType="VARCHAR" property="lastName" />
    <result column="gender" jdbcType="CHAR" property="gender" />
    <result column="email" jdbcType="VARCHAR" property="email" />
    <result column="dept_id" jdbcType="INTEGER" property="deptId" />
  </resultMap>
  <sql id="Base_Column_List">
    <!--
      WARNING - @mbg.generated
      This element is automatically generated by MyBatis Generator, do not modify.
      This element was generated on Mon Sep 03 10:51:01 CST 2018.
    -->
    id, last_name, gender, email, dept_id
  </sql>
  <select id="selectByPrimaryKey" parameterType="java.lang.Integer" resultMap="BaseResultMap">
    <!--
      WARNING - @mbg.generated
      This element is automatically generated by MyBatis Generator, do not modify.
      This element was generated on Mon Sep 03 10:51:01 CST 2018.
    -->
    select 
    <include refid="Base_Column_List" />
    from tbl_employee
    where id = #{id,jdbcType=INTEGER}
  </select>
  <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer">
    <!--
      WARNING - @mbg.generated
      This element is automatically generated by MyBatis Generator, do not modify.
      This element was generated on Mon Sep 03 10:51:01 CST 2018.
    -->
    delete from tbl_employee
    where id = #{id,jdbcType=INTEGER}
  </delete>
  <insert id="insert" parameterType="com.tangge.bean.Employee">
    <!--
      WARNING - @mbg.generated
      This element is automatically generated by MyBatis Generator, do not modify.
      This element was generated on Mon Sep 03 10:51:01 CST 2018.
    -->
    insert into tbl_employee (id, last_name, gender, 
      email, dept_id)
    values (#{id,jdbcType=INTEGER}, #{lastName,jdbcType=VARCHAR}, #{gender,jdbcType=CHAR}, 
      #{email,jdbcType=VARCHAR}, #{deptId,jdbcType=INTEGER})
  </insert>
  <insert id="insertSelective" parameterType="com.tangge.bean.Employee">
    <!--
      WARNING - @mbg.generated
      This element is automatically generated by MyBatis Generator, do not modify.
      This element was generated on Mon Sep 03 10:51:01 CST 2018.
    -->
    insert into tbl_employee
    <trim prefix="(" suffix=")" suffixOverrides=",">
      <if test="id != null">
        id,
      </if>
      <if test="lastName != null">
        last_name,
      </if>
      <if test="gender != null">
        gender,
      </if>
      <if test="email != null">
        email,
      </if>
      <if test="deptId != null">
        dept_id,
      </if>
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides=",">
      <if test="id != null">
        #{id,jdbcType=INTEGER},
      </if>
      <if test="lastName != null">
        #{lastName,jdbcType=VARCHAR},
      </if>
      <if test="gender != null">
        #{gender,jdbcType=CHAR},
      </if>
      <if test="email != null">
        #{email,jdbcType=VARCHAR},
      </if>
      <if test="deptId != null">
        #{deptId,jdbcType=INTEGER},
      </if>
    </trim>
  </insert>
  <update id="updateByPrimaryKeySelective" parameterType="com.tangge.bean.Employee">
    <!--
      WARNING - @mbg.generated
      This element is automatically generated by MyBatis Generator, do not modify.
      This element was generated on Mon Sep 03 10:51:01 CST 2018.
    -->
    update tbl_employee
    <set>
      <if test="lastName != null">
        last_name = #{lastName,jdbcType=VARCHAR},
      </if>
      <if test="gender != null">
        gender = #{gender,jdbcType=CHAR},
      </if>
      <if test="email != null">
        email = #{email,jdbcType=VARCHAR},
      </if>
      <if test="deptId != null">
        dept_id = #{deptId,jdbcType=INTEGER},
      </if>
    </set>
    where id = #{id,jdbcType=INTEGER}
  </update>
  <update id="updateByPrimaryKey" parameterType="com.tangge.bean.Employee">
    <!--
      WARNING - @mbg.generated
      This element is automatically generated by MyBatis Generator, do not modify.
      This element was generated on Mon Sep 03 10:51:01 CST 2018.
    -->
    update tbl_employee
    set last_name = #{lastName,jdbcType=VARCHAR},
      gender = #{gender,jdbcType=CHAR},
      email = #{email,jdbcType=VARCHAR},
      dept_id = #{deptId,jdbcType=INTEGER}
    where id = #{id,jdbcType=INTEGER}
  </update>
</mapper>

3.Example的使用

QBC风格的带条件查询

@Test
public void test01(){
SqlSession openSession = build.openSession();
DeptMapper mapper = openSession.getMapper(DeptMapper.class);
DeptExample example = new DeptExample();
//所有的条件都在example中封装
Criteria criteria = example.createCriteria();
//select id, deptName, locAdd from tbl_dept WHERE 
//( deptName like ? and id > ? ) 
criteria.andDeptnameLike("%部%");
criteria.andIdGreaterThan(2);
List<Dept> list = mapper.selectByExample(example);
for (Dept dept : list) {
	System.out.println(dept);
	}
}