IDEA+mybatis实现增删改查(CURD)

0.前言

操作mybaits和mysql进行增删改查是必备的一步，今天写一篇文章简单记录一下mybatis的增删改查操作。

本文源代码放在github上。

1.具体操作

studnetsMapper文件

package com.cat.dao;

import com.cat.pojo.Students;
import java.util.List;

public interface StudentsMapper {
    //所有学生
    List<Students> listAllStudents();

    //删除一名学生信息
    int deleteStudent(int id);

    //新增一名学生
    int addStudent(Students students);

    //修改一名学生信息
    int updateStudentById(Students students);


}

StudentsMapper.xml文件

<?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.cat.dao.StudentsMapper">
    <!--展示所有学生-->
    <select id="listAllStudents" resultType="com.cat.pojo.Students">
        select * from students;
    </select>

    <!--删除一条学生信息-->
    <delete id="deleteStudent" parameterType="int">
         delete from students where id = #{id}
    </delete>

    <!--增加一名学生信息-->
    <insert id="addStudent" parameterType="com.cat.pojo.Students">
         insert into students(stu_name,stu_sex,class_id,age)
            values (#{stu_name},#{stu_sex},#{class_id},#{age})
    </insert>
    <!--更新一名学生的信息-->
    <update id="updateStudentById"  parameterType="com.cat.pojo.Students">
        update students set
        stu_name= #{stu_name},
        stu_sex= #{stu_sex},
        class_id =#{class_id},
        age=#{age}
        where  id =#{id}
    </update>
</mapper>

Test文件

package com.cat.test;
import com.cat.dao.StudentsMapper;
import com.cat.pojo.Students;
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.Test;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class MyBatisTest {

    //输出所有学生信息
    @Test
    public void  test() throws IOException{
        //获得核心配置文件
        InputStream in = Resources.getResourceAsStream("MyBatisConfig.xml");
        //获得session工厂对象
        SqlSessionFactoryBuilder builder =new SqlSessionFactoryBuilder();
        SqlSessionFactory factory=builder.build(in);
        SqlSession session =factory.openSession();
        //获得会话对象
        List<Students> students =session.selectList("listAllStudents");
        System.out.println(students);
        session.close();  //关闭
    }

    //测试删除一名学生信息
    @Test
    public void deleteStudent() throws  IOException{
        //获得核心配置文件
        InputStream in = Resources.getResourceAsStream("MyBatisConfig.xml");
        //获得session工厂对象
        SqlSessionFactoryBuilder builder =new SqlSessionFactoryBuilder();
        SqlSessionFactory factory=builder.build(in);
        SqlSession session =factory.openSession();
        //获得会话对象
        StudentsMapper studentsMapper = session.getMapper(StudentsMapper.class);
        studentsMapper.deleteStudent(1000);  //调用deleteStudent方法，删除id是1000的这个学生
        session.close();  //关闭
    }

    //新增一名学生信息
    @Test
    public void addStudent() throws  IOException{
        //获得核心配置文件
        InputStream in = Resources.getResourceAsStream("MyBatisConfig.xml");
        //获得session工厂对象
        SqlSessionFactoryBuilder builder =new SqlSessionFactoryBuilder();
        SqlSessionFactory factory=builder.build(in);
        SqlSession session =factory.openSession();
        //获得会话对象
        StudentsMapper studentsMapper = session.getMapper(StudentsMapper.class);
        //构造一个新的学生
        Students s =new Students();

        s.setStu_name("呵呵");
        s.setClass_id(1042);
        s.setAge(16);
        s.setStu_sex("男");

        int res = studentsMapper.addStudent(s);  //调用

        session.commit(); //增删改必须提交事务
        session.close();  //关闭
    }

    //修改一名学生信息
    @Test
    public  void updateStudent() throws  IOException{
        //获得核心配置文件
        InputStream in = Resources.getResourceAsStream("MyBatisConfig.xml");
        //获得session工厂对象
        SqlSessionFactoryBuilder builder =new SqlSessionFactoryBuilder();
        SqlSessionFactory factory=builder.build(in);
        SqlSession session =factory.openSession();
        //获得会话对象
        StudentsMapper studentsMapper = session.getMapper(StudentsMapper.class);

        //把原来的学生信息修改
        Students s= new Students();
        s.setId(1001);  //定向修改id是1001的学生
        s.setStu_name("李十三"); //这个人的名字改成李十三
        s.setStu_sex("男"); //性别改为男
        s.setAge(24); //年龄修改为24
        s.setClass_id(3002);

        int res = studentsMapper.updateStudentById(s);  //调用
        session.commit(); //增删改必须提交事务
        session.close();  //关闭
    }

}