Java笔记之Mybatis(二):增删改查

0.前言

　　(1).以下操作基于Mybatis(一):简单入门已存在的数据;

　　(2).mybatisConfig.xml中已开启驼峰命名规则映射;

1.修改Student.xml

<?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.mybatis.demo.pojo">
    <!-- 查询所有的Student信息 -->
    <select id="getAllStudent" resultType="Student">
        select 
            student_id,
            student_name,
            student_age
        from 
            t_student
    </select>
    
    <!-- 根据ID查询Student的信息 -->
    <select id="getStudentById" parameterType="int" resultType="Student">
        select 
            * 
        from 
            t_student 
        where 
            student_id=#{value}
    </select>
    
    <!-- 新增Student信息 -->
    <insert id="addStudent" parameterType="Student">
        insert 
        into 
            t_student 
        values(
            null,
            #{studentName},
            #{studentAge}
        )
    </insert>
    
    <!-- 根据ID删除指定的Student信息 -->
    <delete id="deleteStudentById" parameterType="int">
        delete 
            from t_student 
        where 
            student_id=#{value}
    </delete>
    
    <!-- 根据ID更新Student信息 -->
    <update id="updateStudentById" parameterType="Student">
        update 
            t_student 
        set 
            student_name=#{studentName},
            student_age=#{studentAge} 
        where 
            student_id=#{studentId}
    </update>
</mapper>

2.修改MybatisTest类

package com.mybatis.demo.test;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

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 com.mybatis.demo.pojo.Student;

public class MybatisTest {

    public static void main(String[] args) throws IOException {
        //加载mybatis的配置文件
        InputStream inputStream = Resources.getResourceAsStream("mybatisConfig.xml");
        //获取SqlSessionFactory对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        //使用SqlSessionFactory对象创建SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        
        System.out.println("======新增操作开始======");
        Student student = new Student();
        student.setStudentName("小明");
        student.setStudentAge(10);
        addStudent(sqlSession, student);
        getAllStudent(sqlSession);
        System.out.println("======新增操作结束======");
        System.out.println("======修改操作开始======");
        updateStudentById(sqlSession, 1);
        getAllStudent(sqlSession);
        System.out.println("======修改操作结束======");
        System.out.println("======删除操作开始======");
        deleteStudentById(sqlSession, 1);
        getAllStudent(sqlSession);
        System.out.println("======删除操作结束======");
        System.out.println("======查询操作开始======");
        getStudentById(sqlSession, 2);
        System.out.println("======查询操作结束======");
    }
    
    /**
     * 根据学生ID获取学生信息
     * @param sqlSession
     * @param studentId
     */
    private static void getStudentById(SqlSession sqlSession,int studentId){
        Student student = sqlSession.selectOne("getStudentById",studentId);
        if(student!=null){
            System.out.println(student.getStudentId()+"\t"+student.getStudentName()+"\t"+student.getStudentAge());
        }else{
            System.out.println("未查询到指定ID的学生信息");
        }
        
    }
    
    /**
     * 查询所有的学生信息
     * @param sqlSession
     */
    private static void getAllStudent(SqlSession sqlSession){
        //查询结果为多条,使用selectList方法,如果结果为一条,使用selectOne方法
        List<Student> students = sqlSession.selectList("getAllStudent");
        //遍历打印学生信息
        for (Student student : students) {
            System.out.println(student.getStudentId()+"\t"+
                    student.getStudentName()+"\t"+student.getStudentAge());
        }
    }
    
    /**
     * 新增学生信息
     * @param sqlSession
     * @param student
     */
    private static void addStudent(SqlSession sqlSession,Student student){
        //返回值为操作影响的行数
        int rows = sqlSession.insert("addStudent", student);
        //提交事务
        sqlSession.commit();
        System.out.println("受影响行数为:"+rows);
    }
    
    /**
     * 根据ID删除学生信息
     * @param sqlSession
     * @param studentId
     */
    private static void deleteStudentById(SqlSession sqlSession,int studentId){
        int rows = sqlSession.delete("deleteStudentById", studentId);
        sqlSession.commit();
        System.out.println("受影响的行数:"+rows);
    }
    
    /**
     * 根据ID修改学生信息
     * @param sqlSession
     * @param studentId
     */
    private static void updateStudentById(SqlSession sqlSession,int studentId){
        Student student = sqlSession.selectOne("getStudentById", studentId);
        if(student!=null){
            student.setStudentName(student.getStudentName()+"001");
            int rows = sqlSession.update("updateStudentById", student);
            sqlSession.commit();
            System.out.println("受影响的行数为:"+rows);
        }else{
            System.out.println("未查询到指定ID的学生信息,请确认");
        }
    }

}

3.运行MybatisTest类,结果如下:

======新增操作开始======
受影响行数为:1
1    张三    23
2    李四    24
3    王五    25
4    赵六    26
5    韩七    27
6    小明    10
======新增操作结束======
======修改操作开始======
受影响的行数为:1
1    张三001    23
2    李四    24
3    王五    25
4    赵六    26
5    韩七    27
6    小明    10
======修改操作结束======
======删除操作开始======
受影响的行数:1
2    李四    24
3    王五    25
4    赵六    26
5    韩七    27
6    小明    10
======删除操作结束======
======查询操作开始======
2    李四    24
======查询操作结束======