Mybatis学习笔记(三)配置文档

XML文档配置

<?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>
    <!--通过属性可以将值进行外部配置，从而实现动态替换 -->
    <!--mysql.properties
    username = dev_user
    password = F2Fa3!33TYyg -->
    <properties resource="mysql.properties"/>

    <settings>
        <!-- 开启日志-->
        <setting name="logImpl" value="LOG4J"/>
        <!--驼峰命名映射，userName可以对应user_name-->
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>
    <!-- 为 Java 类型设置全局的缩写名字，为其他配置文件降低冗余的全限定类名书写-->
    <typeAliases>
        <!-- 包扫描，默认把包下的所有类都赋予一个Bean首字母小写的别名-->
        <package name="com.hjc.POJO"/>
        <typeAlias alias="Blog" type="domain.blog.Blog"/>
    </typeAliases>

    <!--尽管可以配置多个环境，但每个 SqlSessionFactory 实例只能选择一种环境，通过构造函数参数选择environment的id，否则使用default的environment-->
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="${url}"/>
                <property name="username" value="${username}"/>
                <property name="password" value="${password}"/>
            </dataSource>
        </environment>
    </environments>
    <!---告诉 MyBatis 去哪里找映射文件-->
    <!-- 一般会在resource下建一个对应接口所在包的文件夹-->
    <mappers>
        <mapper resource="com/hjc/mapper/UserMapper.xml"/>
        <mapper resource="com/hjc/mapper/PhoneMapper.xml"/>
    </mappers>
</configuration>

 

Mapper映射文件配置

 <?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">
<!--namespace：对应的接口文件-->
<mapper namespace="com.hjc.mapper.UserMapper">

<!--id：对应接口的函数方法-->
  <update id="updateUser">
<!--传参方法：
 @Param("userid") int userid 
 @Param("user") User user ，使用的时候#{user.id}-->
    update  mybatis.user set name = #{name},pwd=#{pwd} where id = #{id};
  </update >

    <delete id="deleteUser" >
    delete from mybatis.user where id = #{id};
  </delete >
    <insert id="insertUser" >
    insert into mybatis.user(id,name,pwd) values(#{id},#{name},#{pwd});
  </insert >
<!-- resultType:传入类名，并要求类属性和数据库列名要一一对应否则取值为Null-->
  <select id="getUserByLimit" resultType="user">
    select * from mybatis.user limit ${start},${number};
  </select>

<!-- resultMap:自定义属性和数据库列名的对应关系-->
<!-- id:标识符，用于别人通过标识符引用
type:该map对应的java类型-->
  <resultMap id="userMap" type="user">
<!--id:通常对应主键，写一个id往往会提升速度
property:变量名
column:数据库列名-->
    <id property="id" column="uid"/>
    <result property="name" column="tname"/>
    <result property="pwd" column="pwd"/>

<!-- 多对一-->
<!--ofType:集合中的类型名，它没有javaType-->
    <collection property="phones" ofType="phone" resultMap="phoneMap"/>
  </resultMap>
  <resultMap id="phoneMap" type="phone">
    <id property="id" column="pid"/>
    <result property="name" column="pname"/>
    <result property="price" column="price"/>
  </resultMap>
    <select id="getUserList" resultMap="userMap">
    select p.id as pid,p.name pname,p.price,u.id as uid ,u.name tname,u.pwd
from user u left outer join phone p on  p.userid = u.id;
  </select>

<!-- 一对多 -->
    <resultMap id="phoneMap" type="phone">
        <id property="id" column="pid"/>
        <result property="name" column="pname"/>
        <result property="price" column="price"/>
        <association property="user" javaType="user">
            <result property="name" column="pname"></result>
            <result property="pwd" column="pwd"></result>
        </association>
    </resultMap>
    <select id="getPhones" resultMap="phoneMap">
    select p.id as pid,p.name pname,p.price,u.id as uid ,u.name tname,u.pwd
    from phone p left outer join user u on p.userid = u.id;
  </select>
</mapper>