MyBatis的简单使用

Posted 2020-10-07 bluedarkni

使用接口代理是需要注意：

1.xml和java接口必须同包同名

2.主xml文件中<mapper>标签中‘class’属性需要映射到接口

3.被映射的xml（和接口同名）中<mapper namespace="接口全路径">

4.操作标签（增删改查）的id和接口中方法名一致

5.接口不需要实现，SqlSessionFactory获取SqlSession对象，再通过反射sqlSession.getMapper(接口名.class) 得到对象，调用接口方法;

InputStream is = Resources.getResourceAsStream("com/bwf01/config/main.xml");//读主配置文件
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
SqlSession sqlSession = sqlSessionFactory.openSession();
接口 jm = sqlSession.getMapper(接口.class);//jm 调用直接接口中的方法

　　

主xml文件：设置配置文件（连接数据的参数），设置日志，设置映射等。

<?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>
    <!-- 设置配置文件 -->
    <properties resource="com/bwf01/config/sqlConfig.properties">
            <property name="driver" value="driver"/>
            <property name="url" value="url"/>
            <property name="username" value="user"/>
            <property name="password" value="password"/>
    </properties>
    <!-- 设置映射别名   别名是为 Java 类型设置一个短的名字
    <typeAliases>
         <typeAlias type="" alias=""/>         
    </typeAliases> -->
    <settings><!-- 配置日志 -->
    <setting name="logImpl" value="LOG4J"/>
    </settings>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC">            
            </transactionManager>
            <dataSource type="POOLED">
            <property name="driver" value="${driver}"/>
            <property name="url" value="${url}"/>
            <property name="username" value="${user}"/>
            <property name="password" value="${password}"/>
            </dataSource>
        </environment>
    </environments>
<!-- 设置映射 和接口同名的xml文件-->    
<mappers>
     <mapper class="com.bwf01.mapper.JobMapper"></mapper>
     <mapper class="com.bwf01.mapper.UserMapper"></mapper>
     <mapper class="com.bwf01.mapper.FirmMapper"></mapper>
     <mapper class="com.bwf01.mapper.AdminMapper"></mapper>
     <mapper class="com.bwf01.mapper.PVMapper"></mapper>
</mappers>
</configuration>

实现接口代理的xml文件：

1.操作标签（增删改查）的id和接口中方法名一致

2.数据库字段和类属性的映射对应

3.配置字段和属性映射时可以使用 extends 

4.操作标签中可以用动态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.bwf01.mapper.JobMapper">
  
  <resultMap type="com.bwf01.bean.Job" id="shareselectJob">
      <!--数据库字段和类属性的映射对应  -->
      <id column="jobId" property="jobId"/>
         <result column="jobName" property="jobName"/>
         <result column="workPlace" property="workPlace"/>
         <result column="workType" property="workType"/>
         <result column="numbers" property="numbers"/>
         <result column="salary" property="salary"/>
         <result column="payType" property="payType"/>
         <result column="workDate" property="workDate"/>
         <result column="workTime" property="workTime"/>
         <result column="endDate" property="endDate"/>
         <result column="firmId" property="firmId"/>
         <result column="principal" property="principal"/>
         <result column="tell" property="tell"/>
         <result column="workDetails" property="workDetails"/>
         <result column="status" property="status"/>
         <result column="curentNum" property="curentNum"/>
         <result column="joinStatus" property="joinStatus"/>
  </resultMap>
  
  <resultMap type="com.bwf01.bean.Job" id="selectJob" extends="shareselectJob">
              <!-- 某个属性是自定义类型，联表查询映射到一个表中的对应字段 -->         
         <association property="firm" javaType="com.bwf01.bean.Firm">
            <id column="firmId" property="firmId"/>
            <result column="logo" property="logo"/>
            <result column="firmName" property="firmName"/>
        </association>
        <!-- 某个属性是自定义类型，联表查询映射到一个表中的对应字段 --> 
        <association property="jobKind" javaType="com.bwf01.bean.JobKind">
            <id column="kindId" property="kindId"/>
            <result column="jobStyle" property="jobStyle"/>
        </association>
  </resultMap>
<select id="selectJobByPage" parameterType="com.bwf01.vo.JobPage" resultMap="selectJob">
        select job.*,logo,firmName,jobStyle from job INNER JOIN firm join jobkind 
         on job.firmId = firm.firmId and jobkind.kindId = job.kindId 
                    where job.status = ‘审核通过‘ and joinStatus = ‘正在报名‘
    <if test="kindId !=0">
    and job.kindId = #{kindId}
    </if>
    <if test="region!=null and region!=‘‘">
     and job.workPlace like ‘%${region}%‘
    </if>                                
    limit ${(page-1)*10},10    
  </select>
</mapper>