Mapper代理开发

mysql -uroot -p1234
create database mybatis;
use mybatis;

drop table if exists tb_user;

create table tb_user(
	id int primary key auto_increment,
	username varchar(20),
	password varchar(20),
	gender char(1),
	addr varchar(30)
);

INSERT INTO tb_user VALUES (1, '张三', '123', '男', '北京');
INSERT INTO tb_user VALUES (2, '李四', '234', '女', '天津');
INSERT INTO tb_user VALUES (3, '王五', '11', '男', '西安');

select * from tb_user;

• Name：myBatisDemo
• Language：Java
• Build System： Maven
• JDK：选默认的
• Parent：
• Advanced Settings
  • Groupld：org.example
  • Artifactld：untitiled
    

• 在src/main/resources路径下右键新建logback.xml文件，代码如下：

    
    
        
            [%level] %blue(%d{HH:mm:ss.SSS}) %cyan([%thread]) %boldGreen(%logger{15}) - %msg %n
        
    

    
        
    
    
    
        
    

• 编辑pom.xml文件，导入依赖包

    4.0.0

    org.example
    myBatisDemo
    1.0-SNAPSHOT

    
        17
        17
    

    

        
        
            org.mybatis
            mybatis
            3.5.9
        
        
        
            mysql
            mysql-connector-java
            5.1.32
        

        
            junit
            junit
            4.13
            test
        

        
        
            org.slf4j
            slf4j-api
            1.7.20
        
        
        
            ch.qos.logback
            logback-classic
            1.2.3
        
        
        
            ch.qos.logback
            logback-core
            1.2.3
        
    

• 在src/main/java下右键新建java class文件：pojo.User
• 声明成员变量

	 private int id ;
	 private String username ;
	 private String password ;
	 private String gender ;
	 private String addr;

• 为成员变量添加geter/seter方法

public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public String getAddr() {
        return addr;
    }

    public void setAddr(String addr) {
        this.addr = addr;
    }

• 添加toString()方法

 @Override
    public String toString() {
        return "User{" +
                "id='" + id + ''' +
                ", username='" + username + ''' +
                ", password='" + password + ''' +
                ", gender='" + gender + ''' +
                ", addr='" + addr + ''' +
                '}';
    }

• 在src/main/java下右键新建com.mappers.UserMapper接口类
• 为接口添加selectAll()方法，并用List接收

package com.mappers;
import pojo.User;
import java.util.List;
public interface UserMapper {
    List selectAll();
}

• 在src/main/resources下右键 --> 新建File：mybatis-config.xml
• 配置mybatis-config.xml核心配置文件

• 在src/main/resources下右键 --> 新建File：com/mappers/UserMapper.xml
• 编写UserMapper.xml代码：

    
        select * from tb_user;
    

• 在src/main/java下右键新建java class文件：MyBatisTest
• 编写主程序代码

import com.mappers.UserMapper;
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 pojo.User;

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

public class MyBatisTest {
    public static void main(String[] args) throws IOException {
        // 1. 加载mybatis的核心配置文件，获取SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        // 2.获取SqlSession对象，用它来执行sql
        SqlSession sqlSession = sqlSessionFactory.openSession();

        // 3. 获取UserMapper接口的代理对象
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        
        // 4. 执行sql
        List users = userMapper.selectAll();
        
        // 5. 打印输出
        System.out.println(users);

        // 6. 释放资源
        sqlSession.close();
    }
}