【xue-gao】mybatis源码阅读——XML之config与mapper解读

RedBeanIce_
180 阅读1分钟

config.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!--

       Copyright 2009-2016 the original author or authors.

       Licensed under the Apache License, Version 2.0 (the "License");
       you may not use this file except in compliance with the License.
       You may obtain a copy of the License at

          http://www.apache.org/licenses/LICENSE-2.0

       Unless required by applicable law or agreed to in writing, software
       distributed under the License is distributed on an "AS IS" BASIS,
       WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
       See the License for the specific language governing permissions and
       limitations under the License.

-->
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <!-- 属性：定义配置外在化 -->
    <properties resource="jdbc.properties"/>

    <!-- 设置：定义mybatis的一些全局性设置 -->
    <settings>
        <setting name="cacheEnabled" value="false"/>
        <setting name="lazyLoadingEnabled" value="false"/>
        <setting name="multipleResultSetsEnabled" value="true"/>
        <setting name="useColumnLabel" value="true"/>
        <setting name="useGeneratedKeys" value="false"/>
        <setting name="defaultExecutorType" value="SIMPLE"/>
        <setting name="defaultStatementTimeout" value="25"/>
    </settings>

    <!-- 类型名称：为一些类定义别名 -->
    <!--    <typeAliases>-->
    <!--        <typeAlias alias="Author" type="domain.blog.Author"/>-->
    <!--    </typeAliases>-->
    <!--    <typeAliases>-->
    <!--        <package name="domain.blog"/>-->
    <!--    </typeAliases>-->

    <!-- 类型处理器：定义Java类型与数据库中的数据类型之间的转换关系 -->
    <!--    <typeHandlers>-->
    <!--        <typeHandler handler="org.mybatis.example.ExampleTypeHandler"/>-->
    <!--    </typeHandlers>-->
    <!--    <typeHandlers>-->
    <!--        <package name="org.mybatis.example"/>-->
    <!--    </typeHandlers>-->
    <!--    <typeHandlers>-->
    <!--        <typeHandler handler="org.apache.ibatis.type.EnumOrdinalTypeHandler" javaType="java.math.RoundingMode"/>-->
    <!--    </typeHandlers>-->

    <!-- 对象工厂 -->
    <!--    <objectFactory type="org.mybatis.example.ExampleObjectFactory">-->
    <!--        <property name="someProperty" value="100"/>-->
    <!--    </objectFactory>-->

    <!--    MyBatis 允许您在执行映射语句时拦截对某些点的调用。默认情况下，MyBatis 允许插件拦截以下方法调用：-->
    <!--    执行器（更新、查询、刷新语句、提交、回滚、getTransaction、close、isClosed）-->
    <!--    ParameterHandler （getParameterObject， setParameters）-->
    <!--    ResultSetHandler （handleResultSets， handleOutputParameters）-->
    <!--    语句处理程序（准备、参数化、批处理、更新、查询）-->
    <!-- 插件：mybatis的插件,插件可以修改mybatis的内部运行规则 -->
    <!--    https://mybatis.org/mybatis-3/configuration.html-->
    <!--    <plugins>-->
    <!--        <plugin interceptor="org.mybatis.example.ExamplePlugin">-->
    <!--            <property name="someProperty" value="100"/>-->
    <!--        </plugin>-->
    <!--    </plugins>-->

    <!-- 环境：配置mybatis的环境 -->
    <!-- 设置一个默认的连接环境信息 -->
    <environments default="development">
        <!-- 连接环境信息，取一个任意唯一的名字 -->
        <environment id="development">
            <!-- mybatis使用jdbc事务管理方式 -->
            <transactionManager type="JDBC"/>
            <!-- mybatis使用连接池方式来获取连接 -->
            <dataSource type="POOLED">
                <!-- 配置与数据库交互的4个必要属性 -->
                <property name="driver" value="${driver}"/>
                <property name="url" value="${url}"/>
                <property name="username" value="${username}"/>
                <property name="password" value="${password}"/>
            </dataSource>
        </environment>
        <!--        &lt;!&ndash; 连接环境信息，取一个任意唯一的名字 &ndash;&gt;-->
        <!--        <environment id="oracle_developer">-->
        <!--            &lt;!&ndash; mybatis使用jdbc事务管理方式 &ndash;&gt;-->
        <!--            <transactionManager type="jdbc"/>-->
        <!--            &lt;!&ndash; mybatis使用连接池方式来获取连接 &ndash;&gt;-->
        <!--            <dataSource type="pooled">-->
        <!--                &lt;!&ndash; 配置与数据库交互的4个必要属性 &ndash;&gt;-->
        <!--                <property name="driver" value="${oracle.driver}"/>-->
        <!--                <property name="url" value="${oracle.url}"/>-->
        <!--                <property name="username" value="${oracle.username}"/>-->
        <!--                <property name="password" value="${oracle.password}"/>-->
        <!--            </dataSource>-->
        <!--        </environment>-->
    </environments>

    <!-- 数据库厂商标识 -->
    <!--    <databaseIdProvider type="DB_VENDOR">-->
    <!--        <property name="SQL Server" value="sqlserver"/>-->
    <!--        <property name="DB2" value="db2"/>-->
    <!--        <property name="Oracle" value="oracle" />-->
    <!--    </databaseIdProvider>-->

    <!-- 映射器：指定映射文件或者映射类 -->
    <mappers>
        <mapper resource="com/atguigu/dao/UserMapper.xml"/>
    </mappers>
</configuration>

setting

cacheEnabled

这个是用来控制是用那个Executor执行sql，主要有 BaseExecutor，CachingExecutor 等

true = CachingExecutor false = BaseExecutor

mapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!--
       Copyright 2009-2012 the original author or authors.

       Licensed under the Apache License, Version 2.0 (the "License");
       you may not use this file except in compliance with the License.
       You may obtain a copy of the License at

          http://www.apache.org/licenses/LICENSE-2.0

       Unless required by applicable law or agreed to in writing, software
       distributed under the License is distributed on an "AS IS" BASIS,
       WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
       See the License for the specific language governing permissions and
       limitations under the License.
-->
<!DOCTYPE mapper
    PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
    "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="org.apache.ibatis.domain.blog.mappers.AuthorMapper">

<resultMap id="selectAuthor" type="org.apache.ibatis.domain.blog.Author">
   <id column="id" property="id" />
   <result property="username" column="username" />
   <result property="password" column="password" />
   <result property="email" column="email" />
   <result property="bio" column="bio" />
   <result property="favouriteSection" column="favourite_section" />
</resultMap>

<select id="selectAllAuthors" resultType="org.apache.ibatis.domain.blog.Author">
   select * from author
</select>

<select id="selectAuthorLinkedHashMap" resultType="java.util.LinkedHashMap">
   select id, username from author where id = #{value}
</select>

<select id="selectAuthor" resultMap="selectAuthor">
   select id, username, password, email, bio, favourite_section
   from author where id = ?
</select>

<insert id="insertAuthor" parameterType="org.apache.ibatis.domain.blog.Author">
   insert into Author (id,username,password,email,bio)
   values (#{id},#{username},#{password},#{email},#{bio})
</insert>

<update id="updateAuthor" parameterType="org.apache.ibatis.domain.blog.Author">
   update Author
   set username=#{username,
   javaType=String},
   password=#{password},
   email=#{email},
   bio=#{bio}
   where id=#{id}
</update>

<delete id="deleteAuthor" parameterType="int">
   delete from Author where id = #{id}
</delete>


<update id="updateAuthorIfNecessary" parameterType="org.apache.ibatis.domain.blog.Author">
   update Author
   <set>
      <if test="username != null">username=#{username},</if>
      <if test="password != null">password=#{password},</if>
      <if test="email != null">email=#{email},</if>
      <if test="bio != null">bio=#{bio}</if>
   </set>
   where id=#{id}
</update>

</mapper>

区别

config.xml

<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">

mapper.xml

<!DOCTYPE mapper
    PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
    "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
avatar
文章
阅读
粉丝