Mybatis最佳实践-01

JDBC外部配置文件：jdbcConfig.xml

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/eesy_mybatis
jdbc.username=root
jdbc.password=root

SqlMapConfig.xml---Mybatis主配置文件

<?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>
    <!-- 配置properties-->
    <properties resource="jdbcConfig.properties"></properties>

    <settings>
        <setting name="cacheEnabled" value="true"/>
    </settings>
    
    <!--使用typeAliases配置别名，它只能配置domain中类的别名 -->
    <typeAliases>
        <package name="com.itheima.domain"></package>
    </typeAliases>

    <!--配置环境-->
    <environments default="mysql">
        <!-- 配置mysql的环境-->
        <environment id="mysql">
            <!-- 配置事务 -->
            <transactionManager type="JDBC"></transactionManager>

            <!--配置连接池-->
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"></property>
                <property name="url" value="${jdbc.url}"></property>
                <property name="username" value="${jdbc.username}"></property>
                <property name="password" value="${jdbc.password}"></property>
            </dataSource>
        </environment>
    </environments>
    <!-- 配置映射文件的位置 -->
    <mappers>
        <package name="com.itheima.dao"></package>
    </mappers>
</configuration>

xxxDao.xml---映射配置文件

<?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.itheima.dao.IUserDao">
  
  <!--开启二级缓存的支持-->
  <cache></cache>
  
  <resultMap id="userMap" type="user">
    <id column="id" property="id"></id>
    <result column="username" property="username"></result>
    <result column="address" property="address"></result>
    <result column="sex" property="sex"></result>
    <result column="birthday" property="birthday"></result>
    <collection property="accounts" ofType="account" column="id"
        select="com.itheima.dao.IAccountDao.findAccountByUid">
    </collection>
  </resultMap>
  
  <!--查询所有-->
  <select id="findAll" resultType="user">
    SELECT * FROM user;
  </select>

<!--根据id查询用户-->
  <select id="findById" parameterType="int" resultType="user" useCache="true">
    SELECT * FROM user WHERE id = #{id};
  </select>
  
  <update id="updateUser" parameterType="user" >
    UPDATE user set username=#{username},birthday=#{birthday},sex=#{sex},address=#{address} WHERE id=#{id}
  </update>
  
</mapper>

<?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.itheima.dao.IAccountDao">

  <!--
  <association property="user" column="uid" javaType="user">
      <id column="id" property="id"></id>
      <result column="username" property="username"></result>
      <result column="sex" property="sex"></result>
      <result column="birthday" property="birthday"></result>
      <result column="address" property="address"></result>
    </association>
  -->
  
  <!--建立对应的关系-->
  <resultMap id="accountMap" type="account">
    <id column="id" property="id"></id>
    <result column="uid" property="uid"></result>
    <result column="money" property="money"></result>
    <!--它是用于指定从表方的引用实体属性的-->
    <association property="user" column="uid" javaType="user"
                 select="com.itheima.dao.IUserDao.findById">
    </association>
  </resultMap>
  
  <!--查询所有-->
  <select id="findAll" resultMap="accountMap">
    SELECT * FROM  account;
   </select>
   
  <!--根据用户id查询账户列表-->
  <select id="findAccountByUid" 
          parameterType="int" resultType="account">
    SELECT * FROM account WHERE uid=#{uid};
  </select>
  
 </mapper>

 

--- 注释版本 ---

<?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">
<!-- mybatis的主配置文件 -->
<configuration>
    
    <properties resource="jdbcConfig.properties">
      <!--  <property name="driver" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/eesy_mybatis"/>
        <property name="username" value="root"/>
        <property name="password" value="root"/>-->
    </properties>
    
    <!--配置参数-->
    <settings>
        <!--开启Mybatis支持延迟加载-->
        <setting name="lazyLoadingEnabled" value="true"/>
        <setting name="aggressiveLazyLoading" value="false"></setting>
        
        <!--开启二级缓存的支持-->
        <!--因为 cacheEnabled 的取值默认就为 true，所以这一步可以省略不配置。为 true 代表开启二级缓存；为 false 代表不开启二级缓存-->
        <setting name="cacheEnabled" value="true"></setting>
    </settings>
    
    <typeAliases>
        <package name="com.itheima.domain"/>
    </typeAliases>
    
    <!-- 配置环境 -->
    <environments default="mysql">
        <!-- 配置mysql的环境-->
        <environment id="mysql">
            <!-- 配置事务的类型-->
            <transactionManager type="JDBC"></transactionManager>
            <!-- 配置数据源（连接池） -->
            <dataSource type="POOLED">
                <!-- 配置连接数据库的4个基本信息 -->
                <property name="driver" value="${jdbc.driver}"/>
                <property name="url" value="${jdbc.url}"/>
                <property name="username" value="${jdbc.username}"/>
                <property name="password" value="${jdbc.password}"/>
            </dataSource>
        </environment>
    </environments>

    <!-- 指定映射配置文件的位置，映射配置文件指的是每个dao独立的配置文件 -->
    <mappers>
        <!--<mapper resource="com/itheima/dao/IUserDao.xml"/>-->
       <!-- package标签是用于指定dao接口所在的包,当指定了之后就不需要在写mapper以及resource或者class了 -->
        <package name="com.itheima.dao"></package>
    </mappers>
</configuration>