Mybatis笔记(第一个Mybatis实例 增删改查)

Mybatis笔记(第一个Mybatis实例 增删改查)

Mybatis：持久性框架

第一个Mybatis程序

搭建环境——导入Mybatis——编写代码——测试

1.1搭建环境

（1）搭建数据库
![在这里插入图片描述](https://img-blog.csdnimg.cn/acbaef9aff5343bb90aa60d34122294e.png

1.2创建项目

a、新建一个普通Maven项目，导入maven依赖

    

        
            mysql
            mysql-connector-java
            5.1.6
            runtime
        


        
            org.mybatis
            mybatis
            3.5.2
        


        
            junit
            junit
            4.12
            test
        
    

b、创建一个模块
编写mybatis核心配置文件

编写mybatis工具类

package com.mybatis.utils;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;


public class MybatisUtils {
    static {
        try{

            //使用Mybatis获取SQLSessionFactory对象
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        }
        catch (IOException e) {
            e.printStackTrace();
        }
    }
}

1.3编写代码

实体类

package com.pojo;

public class User {
    private int id;
    private String name;
    private String pwd;

    public User(){

    }

    public User(int id, String name, String pwd) {
        this.id = id;
        this.name = name;
        this.pwd = pwd;
    }

    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 String getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + ''' +
                ", pwd='" + pwd + ''' +
                '}';
    }
}

Dao接口

package com.mybatis.dao;

import com.mybatis.pojo.User;

import java.util.List;

public interface UserDao {
    //查询全部用户
    List getUserList();

    //根据ID查询用户
    User getUserById(int id);

    //增加用户
    int addUser(User user);

    //修改用户
    int updateUser(User user);

    //删除用户
    int deleteUser(int id);
}

接口实现类改为XML文件（UserMapper.xml）

    
        select * from mybatis.user
    

    
        select * from mybatis.user where id = #{id}
    

    
        insert into mybatis.user(id,name,pwd) values (#{id},#{name},#{pwd})
    

    
        update mybatis.user set name = #{name },pwd= #{pwd} where id = #{id}
    

    
        delete from mybatis.user where id = #{id}
    

测试

package com.dao;

import com.mybatis.dao.UserDao;
import com.mybatis.pojo.User;
import com.mybatis.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class UserDaoTest {

   @Test
    public void Test01(){
       //获取SQLSession对象，实例化对象
      //以下两行重复使用
       SqlSession sqlSession = MybatisUtils.getSqlSession();
       UserDao mapper = sqlSession.getMapper(UserDao.class);


       List userList = mapper.getUserList();

       for (User user : userList) {
           System.out.println(user);
       }

       sqlSession.close();
   }

   @Test
    public void getUserById02(){
       SqlSession sqlSession = MybatisUtils.getSqlSession();

       UserDao mapper = sqlSession.getMapper(UserDao.class);

       User user = mapper.getUserById(1);
       System.out.println(user);

       sqlSession.close();
   }

   @Test
   //增删改需要提交事务
    public void addUser(){
       SqlSession sqlSession = MybatisUtils.getSqlSession();

       UserDao mapper = sqlSession.getMapper(UserDao.class);
       int result = mapper.addUser(new User(4,"丁六","123"));

       
       sqlSession.commit();


       sqlSession.close();
   }

   @Test
    public void updateUser(){
       SqlSession sqlSession = MybatisUtils.getSqlSession();
       UserDao mapper = sqlSession.getMapper(UserDao.class);
       int result = mapper.updateUser(new User(4, "丁六", "147"));
       sqlSession.commit();

       sqlSession.close();
   }

   @Test
   public void deleteUser(){
      SqlSession sqlSession = MybatisUtils.getSqlSession();
      UserDao mapper = sqlSession.getMapper(UserDao.class);
      int result= mapper.deleteUser(4);
      sqlSession.commit();
      sqlSession.close();

   }
}

parameterType

（1）Map传递参数，直接在sql中取出key即可
parameterType = “map”
（2）对象传递参数，直接在sql中取对象的属性即可
parameterType = “User”
（3）只有一个基本类型参数的情况下，可直接在sql中取到
可省略
（4）多个参数用map，或者注解

SqlSessionFactoryBuilder SqlSessionFactory SqlSession