Mybatis1

• 一、数据库
• 二、maven
• 三、XML配置文件
• 四、内容
• • 1.mybatis工具类
  • 2.实体类
  • 3.Dao接口
  • 4.Mapper配置文件
• 五、Junit测试
• 总结

CREATE DATABASE `mybatis`;

USE `mybatis`;

CREATE TABLE `user`(
   `id` INT(20) NOT NULL PRIMARY KEY,
   `name` VARCHAr(30) DEFAULT NULL,
   `pwd` VARCHAr(30) DEFAULT NULL
)ENGINE=INNODB DEFAULT CHARSET=utf8;

INSERT INTO `user`(`id`,`name`,`pwd`) VALUES
(1,'张三','123456'),(2,'赵四','123456'),(3,'王五','123456')

导入依赖jar包

        
        
            mysql
            mysql-connector-java
            5.1.47
        
        
        
            org.mybatis
            mybatis
            3.5.6
        

        
        
            junit
            junit
            4.12
        

        

    

在resource文件夹下，创建mybatis-config.xml文件，编写mybatis的核心配置文件

//工具类，sqlSessionFactory
public class MybatisUtils {

    private static SqlSessionFactory sqlSessionFactory;
    static {
        try {
            //使用mybatis的第一步：获取sqlSessionFactory对象
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static SqlSession getSqlSession(){
        return sqlSessionFactory.openSession();
    }
}

代码如下（示例）：

package com.kuang.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 + ''' +
                '}';
    }
}

代码如下（示例）：

package com.kuang.dao;

import com.kuang.pojo.User;

import java.util.List;

public interface UserDao { // 或者 UserMapper
    List getUserList();
}

接口实现类由原来的UserDaoImpl转化为一个Mapper配置文件（userMapper.xml）

    
        select * from mybatis.user
    

public class UserDaoTest {
    @Test
    public void test(){
        //第一步：获得sqlSession对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();

        //方式一：getMapper
        UserDao userDao = sqlSession.getMapper(UserDao.class);
        List userList = userDao.getUserList();
        for (User user : userList) {
            System.out.println(user);
        }
        //关闭sqlSession
        sqlSession.close();
    }
}

问题

Caused by: org.apache.ibatis.exceptions.PersistenceException: 
### Error building SqlSession.
### The error may exist in com/yd/dao/userdao.xml
### Cause: org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause: java.io.IOException: Could not find resource com/yd/dao/userdao.xml

解决：资源过滤

    
        
            
                src/main/java
                
                    ***.xml
                
                false
            
            
                src/main/resources
                
                    ***.xml
                
                false
            
        
    

1.连接数据库，导入mysql和mybatis jar包
2.建造工具类MybatisUtils获取工厂
3.编写配置文件mybatis-config.xml
4.实体类
5.接口
6.Mapper文件代替实现类
7.junit测试