mybatis之mapper开发

目录结构

   

   

import cn.tri.pojo.Clazz;

协同

   

1. public interface ClazzMapper {
2.     public Clazz findClazzId(int id);
3. }

   

   

• <?xml version="1.0" encoding="UTF-8"?><!--xxMapper.xml-->
• <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
• <mapper namespace="cn.tri.mapper.ClazzMapper">
• <select id="findClazzId" parameterType="int" resultMap="mapClazz">
• SELECT * FROM teacher t,student s,Clazz c where c.c_id = #{id} and c.c_id = s.cid and t.t_id = s.tid;
• </select>
• <resultMap type="cn.tri.pojo.Clazz" id="mapClazz">
• <id property="id" column="c_id"/>
• <result property="name" column="c_name"/>
• <collection property="list" ofType="cn.tri.pojo.Student">
• <id property="id" column="s_id"/>
• <result property="name" column="s_name"/>
• <association property="teacher" javaType="teacher">
• <id property="id" column="t_id"/>
• <result property="name" column="t_name"/>
• </association>
• </collection>
• </resultMap>
• </mapper>

   

   

实体类

   

• package cn.tri.pojo;
• import java.util.List;
• public class Clazz {
•     private int id;
•     private String name;
•     private List<Student> list;
•     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 List<Student> getList() {
•         return list;
•     }
•     public void setList(List<Student> list) {
•         this.list = list;
•     }
•     public Clazz(int id, String name, List<Student> list) {
•         super();
•         this.id = id;
•         this.name = name;
•         this.list = list;
•     }
•     public Clazz() {
•         super();
•     }
•     @Override
•     public String toString() {
•         return "Clazz [id=" + id + ", name=" + name + ", list=" + list + "]";
•     }
• }

   

   

测试

   

• //测试
  
  import java.io.IOException;
• import java.io.InputStream;
• import org.apache.ibatis.io.Resources;
• import org.apache.ibatis.session.SqlSession;
• import org.apache.ibatis.session.SqlSessionFactory;
• import org.apache.ibatis.session.SqlSessionFactoryBuilder;
• import org.junit.Before;
• import org.junit.Test;
• import cn.tri.mapper.ClazzMapper;
• import cn.tri.pojo.Clazz;
• public class ClazzTest {
•     SqlSessionFactory factory = null;
•     @Before
•     public void init() throws IOException{
•         String url = "mybaties-config.xml";
•         InputStream is = Resources.getResourceAsStream(url);
•         factory = new SqlSessionFactoryBuilder().build(is);
•         System.out.println(factory);
•     }
•     
•     @Test
•     public void findClazzId(){
•         SqlSession session = factory.openSession();
•         String statement = "cn.tri.mapper.ClazzMapper.findClazzId";
•         Clazz clazz = session.selectOne(statement, 1);
•         //session.clearCache();//清楚缓存
  
          System.out.println(clazz);
•         //session.close(); //关闭连接
  
      }
• }