首先建表：
CREATE TABLE teacher( t_id INT PRIMARY KEY AUTO_INCREMENT, t_name VARCHAR(20));CREATE TABLE class( c_id INT PRIMARY KEY AUTO_INCREMENT, c_name VARCHAR(20), teacher_id INT);ALTER TABLE class ADD CONSTRAINT fk_teacher_id FOREIGN KEY (teacher_id) REFERENCES teacher(t_id); INSERT INTO teacher(t_name) VALUES('LS1');INSERT INTO teacher(t_name) VALUES('LS2');INSERT INTO class(c_name, teacher_id) VALUES('bj_a', 1);INSERT INTO class(c_name, teacher_id) VALUES('bj_b', 2); 再cn.beam包下，简历两个Class类。分别是Classes.java和Teacher.java
public class Classes { private int id; private String name; private Teacher teacher;}public class Teacher { private int id; private String name;} 然后分别构造方法，做get和set方法。
配置config.xml文件:
配置db.properties
driver=com.mysql.jdbc.Driverurl=jdbc:mysql://localhost:3306/mybatisusername=rootpassword=root
配置mapper文件：
做一个utils
import java.io.InputStream;import junit.framework.Test;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;public class MyBatisUtils { public static SqlSessionFactory getFactory(){ String resource = "conf.xml"; InputStream is = Test.class.getClassLoader().getResourceAsStream(resource); SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is); return factory; }} 做一个测试，测试结果：
import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.junit.Test;import cn.bean.Classes;import cn.utils.MyBatisUtils;public class Test5 { @Test public void selectTeacherByCid(){ SqlSessionFactory factory = MyBatisUtils.getFactory(); SqlSession session = factory.openSession(true); String statement = "cn.test5.ClassMapper.getClass"; Classes c = session.selectOne(statement, 1); System.out.println(c); }} 结果如下：
Classes [id=1, name=bj_a, teacher=Teacher [id=1, name=LS1]]