创建数据库

CREATE DATABASE mybatis;
USE mybatis; 
CREATE TABLE USER ( id INT NOT NULL PRIMARY KEY,
 NAME VARCHAR(64) NOT NULL, 
 pwd VARCHAR(64) NOT NULL )
ENGINE=INNODB DEFAULT CHARSET=utf8; 
INSERT INTO USER (id,NAME,pwd)VALUE (1,'张三','123123');
INSERT INTO USER (id,NAME,pwd)VALUES (2,'小落','12341234'),(3,'李四','1231233');

创建项目

1.创建一个普通的Maven项目

2.删除src目录，形成父工程

3.导入需要的包

        
            mysql
            mysql-connector-java
            5.1.47
        
        
        
            org.mybatis
            mybatis
            3.4.6
        
        
        
            junit
            junit
            4.12
            test
        

4.编辑包的结构

5.编写Mybatis.xml核心配置文件

<?xml version="1.0" encoding="UTF-8" ?>


    
        
            
            
                
                
                
                
            
        
    
    
    
        
    

5.1报错

### Error querying database.  Cause: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet successfully received from the server was 449 milliseconds ago.  The last packet sent successfully to the server was 442 milliseconds ago.

这里的问题出在数据库，所以检查数据库连接。发现useSSL=true
要改为useSSL=false；

6.编写工具类（getSession）

package com.Google.units;


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

public class sqlSessionFactory {
    private static SqlSessionFactory sqlSessionFactory;
    static {
        try {
            String resource = "Mybatis.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    /*sqlsession完全包含了所有面向数据库执行sql语句的所有方法*/
    public static SqlSession getsqlSession(){
        return sqlSessionFactory.openSession();
    }
}

7.编写实体类

package com.Google.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 + '\'' +
                '}';
    }
}

8.编写接口

package com.Google.Dao;

import com.Google.pojo.User;

import java.util.List;

public interface userMapper {
    /*定义一个获取user数据的接口*/
    List getUserList();
}

9.编写Mapper.xml配置文件

<?xml version="1.0" encoding="UTF-8" ?>



    
    
    
        select * from user
    

10测试

package com.Google.Dao;

import com.Google.pojo.User;
import com.Google.units.sqlSessionFactory;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class userDao {
    @Test
    public void test() throws Exception{

        SqlSession sqlSession = sqlSessionFactory.getsqlSession();
        userMapper md =sqlSession.getMapper(userMapper.class);

        List userList = md.getUserList();
        for (User user : userList) {
            System.out.println(user);
        }

    }
}

注意点

1.先把需要配置的再区写测试，防止测试类的名字和Dao一样，这样先写测试类，然后再去配置文件，可能会把测试类配置到Mybatis配置文件中，这样就会报这样的错

type class com.google.dao.usermapper is not known to the mapperregistry.

2.由于Maven中约定大于配置，所以我们配置的文件可能会被过滤掉，只需要加入这些代码，就可解决这样的问题

        
            
                src/main/resources
                
                    **/*.properties
                    **/*.xml
                
                true
            
            
                src/main/java
                
                    **/*.properties
                    **/*.xml
                
                true
            
        
    

3.最常见的错误

org.apache.ibatis.binding.BindingException: Type interface com.Google.Dao.userMapper is not known to the MapperRegistry.

这里就是要在Mybatis.xml和Dao目录下的配置文件一起配置，具体如下

    
    
    
        select * from user