级联查询，一对多

src/test/java/com/tianjunwei/lazy/LazyMainTeacher.java

@@ -0,0 +1,51 @@
+/**
+ *    Copyright  2017  tianjunwei
+ *
+ *    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.
+ */
+package com.tianjunwei.lazy;
+
+import java.io.InputStream;
+import java.util.List;
+
+import org.apache.ibatis.session.SqlSession;
+import org.apache.ibatis.session.SqlSessionFactory;
+import org.apache.ibatis.session.SqlSessionFactoryBuilder;
+
+import com.tianjunwei.lazy.entity.Teacher;
+import com.tianjunwei.lazy.entity.User;
+
+
+/**
+ * @author tianjunwei
+ * @time 2017 上午10:24:21
+ */
+public class LazyMainTeacher {
+public static void main(String [] args){
+
+		//mybatis的配置文件
+	    String resource = "learn/mybatis-config.xml";
+	    InputStream is = LazyMainTeacher.class.getClassLoader().getResourceAsStream(resource);
+	    //构建sqlSession的工厂
+	    SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
+	    SqlSession session = sessionFactory.openSession();
+	    String statement = "com.tianjunwei.lazy.entity.Teacher.getTeacher";//映射sql的标识字符串
+	    //执行查询返回一个唯一user对象的sql
+	    Teacher teacher =  (Teacher) session.selectList(statement, 1).get(0);
+	    session.commit(true);
+	    System.out.println(teacher.getName());
+	    List<User> users = teacher.getUsers();
+	    System.err.println(users.get(3).getAge());
+
+	}
+}

src/test/java/com/tianjunwei/lazy/mapper/TeacherMapper.xml

@@ -0,0 +1,27 @@
+<?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.tianjunwei.lazy.entity.Teacher">
+
+     <select id="getById" parameterType="int" resultMap="user">
+     	select * from users where users.teacher_id=#{id} 
+     </select>
+
+     <select id="getTeacher" resultMap="teacher">
+     	select * from tbl_teacher where id=#{id}
+     </select>
+
+     <resultMap type="com.tianjunwei.lazy.entity.Teacher" id="teacher" >    
+     	<id column="id" property="id" javaType="int" jdbcType="INTEGER"></id>
+     	<result column="name" property="name" javaType="string" jdbcType="VARCHAR"/>
+     	 <collection property="users" column="id"  select="com.tianjunwei.lazy.entity.Teacher.getById" javaType="list">
+     	 </collection>
+     </resultMap>
+
+     <resultMap type="com.tianjunwei.lazy.entity.User" id="user" >    
+     	<id column="id" property="id" javaType="int" jdbcType="INTEGER"></id>
+     	<result column="name" property="names" javaType="string" jdbcType="VARCHAR"/>
+     	<result column="age" property="age" javaType="int" jdbcType="INTEGER"/>
+     </resultMap>
+
+ </mapper>

src/test/reources/learn/mybatis-config.xml

@@ -4,7 +4,7 @@
      <settings>
         <setting name="cacheEnabled" value="true"/>
         <setting name="defaultExecutorType" value="SIMPLE"/> <!--SIMPLE、REUSE、BATCH-->
-        <setting name="aggressiveLazyLoading" value="fasle"/>
+        <setting name="aggressiveLazyLoading" value="false"/>
         <setting name="lazyLoadingEnabled" value="true"/>
      </settings>
      <environments default="development">
@@ -24,6 +24,7 @@
          <mapper resource="com/tianjunwei/learn/learn1/mapper/UserMapper.xml"/>
           <mapper resource="com/tianjunwei/learn/learn2/mapper/UserMapper.xml"/>
           <mapper resource="com/tianjunwei/lazy/mapper/UserMapper.xml"/>
+           <mapper resource="com/tianjunwei/lazy/mapper/TeacherMapper.xml"/>
      </mappers>
 
 </configuration>