一、核心配置文件

二、实体类

　　Classes

package com.myBatis.entity;import java.util.List;public class Classes {    private int id; // id===>c_id    private String name; // name===>c_name    /**     * class表中有一个teacher_id字段，所以在Classes类中定义一个teacher属性，     * 用于维护teacher和class之间的一对一关系，通过这个teacher属性就可以知道这个班级是由哪个老师负责的     */    private Teacher teacher;        //使用一个List
     
      集合属性表示班级拥有的学生     private List
      
        students;        public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public Teacher getTeacher() {        return teacher;    }    public void setTeacher(Teacher teacher) {        this.teacher = teacher;    }        public List
       
         getStudents() {        return students;    }    public void setStudents(List
        
          students) {        this.students = students;    }    @Override    public String toString() {        return "Classes [id=" + id + ", name=" + name + ", teacher=" + teacher + ", students=" + students + "]";    }        //增删改要用到的两个构造方法    public Classes(String name, Teacher teacher) {        super();        this.name = name;        this.teacher = teacher;    }    public Classes() {        super();    }        }
        
       
      
     

　　Teacher

package com.myBatis.entity;public class Teacher {    // 定义实体类的属性，与teacher表中的字段对应    private int id; // id===>t_id    private String name; // name===>t_name    public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    @Override    public String toString() {        return "Teacher [id=" + id + ", name=" + name + "]";    }    public Teacher() {        super();    }    public Teacher(int id) {        super();        this.id = id;    }        }

　　Student

package com.myBatis.entity;public class Student {    //定义属性，和student表中的字段对应    private int id;            //id===>s_id    private String name;    //name===>s_name        public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    @Override    public String toString() {        return "Student [id=" + id + ", name=" + name + "]";    }}

三、映射文件

　　classessMapper.xml

         
         
         
         
              
                   select * from classes c, teacher t where c.t_id=t.t_id and c.c_id=#{id}                
              
                  
                   
                   
                       
                        
                    
               
              
              
      
                   delete from classes where c_id=#{id}        
                
              
      
                   insert into classes values(null,#{name},#{teacher.id})        
               
              
      
                   update classes set t_id=#{teacher.id} where c_id=#{id}        
                        
                 
          
          
              select * from classes c, teacher t,student s where c.t_id=t.t_id and c.c_id=s.class_id and  c.c_id=#{id}        
              
               
               
                   
                    
                
               
               
                   
                    
                
           
                  
     

　　teacherMapper.xml

         
         
             
              
                  select * from classes c, teacher t where c.t_id=t.t_id and t.t_id=#{id}                
              
                  
                   
               
                       
      
                   insert into teacher values(#{t_name})        
                  
     

四、封装类

package com.myBatis.util;import java.io.IOException;import java.io.Reader;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;public class myBtaisUtil {    static Reader reader=null;    static SqlSessionFactory sqlSessionFactory= null;    static SqlSession sqlSession = null;    /**     * 加载核心配置文件     * 获取SqlSessionFactory     * @return SqlSessionFactory     */    public static SqlSessionFactory getsqlSessionFactory() {        try {            reader = Resources.getResourceAsReader("SqlMapConfig.xml");            sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);        } catch (IOException e) {            e.printStackTrace();        }        return sqlSessionFactory;    }    /**     * 获取SqlSession     * @return SqlSession     */    public static SqlSession getsqlSession() {        return sqlSession= getsqlSessionFactory().openSession(true);    }}

五、测试类

package myBatisTest;import org.apache.ibatis.session.SqlSession;import org.junit.Test;import com.myBatis.entity.Classes;import com.myBatis.entity.Teacher;import com.myBatis.util.myBtaisUtil;public class TestUser {    //查询    @Test    public void testGetClasses() {        SqlSession sqlSession=myBtaisUtil.getsqlSession();        String select = "com.myBatis.mapper.classesMapper.getClass3";        Classes classes = sqlSession.selectOne(select, 1);        System.out.println(classes);    }}