记录MyBatis的搭建过程

MyBatis是一个持久层的框架，mybatis可以将向 preparedStatement中的输入参数自动进行输入映射，将查询结果集灵活映射成java对象即输出映射。

PART_ONE:环境搭建和配置文件编写
1.准备基本的user类和数据库user表

package entiy;

import java.io.Serializable;

public class User implements Serializable {
    
    private int id;
    private String name;
    private String address;
    
    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 getAddress() {
        return address;
    }
    public void setAddress(String address) {
        this.address = address;
    }
    @Override
    public String toString() {
        return "User [id=" + id + ", name=" + name + ", address=" + address + "]";
    }
    
    

}

2.在MyBatis官网中下载其jar包

image.png

将jar包导入到工程中。
2.编写SqlMapConfig.xml，这个文件配置基本的数据库连接信息和之后需要的mappers信息。这个文件需要放在资源文件的根下，或者在使用的时候表明位置

3.编写user类对应的UserMapper.xml

    
        
        
    
        select * from t_user where id =#{value}
    
    
    
    
        select * from t_user where name like '%${value}%'
    
    
    
    
        
        SELECT LAST_INSERT_ID()
        
        
        
        insert into t_user (name,address) values (#{name},#{address})
    
    
    
    
        delete from t_user where id =#{id}
    
    
    
    
        update t_user set name=#{name},address=#{address} where id=#{id}
    
    
    
    
        select * from t_user 
        
            
                
                    and address = #{usercustom.address}
                   
            
        
        
    
    
    
    
        
        
    
    
    
    
        select id id_,name name_ from t_user where id = #{id}
    

PART_TWO:基本的CRUD实现，之后还有dao和Mapper的两种方式来实现。

package test;

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

import javax.annotation.Resource;

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 org.junit.jupiter.api.Test;

import entiy.User;

public class domain {
    
    @Test
    public void testselect() throws IOException {
        String resource = "SqlMapConfig.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        //创建SqlsessionFactory
        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        //通过工厂得到sqlsession
        SqlSession sqlsession = sessionFactory.openSession();
        //通过sqlsession操作数据库,第一个参数是User.xml的方法，第二参数是需要传入的值
        User user = sqlsession.selectOne("test.findUserById", 1);
        System.out.println(user);
        sqlsession.close();
    }
    
    @Test
    public void testselectByName() throws IOException {
        String resource = "SqlMapConfig.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        //创建SqlsessionFactory
        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        //通过工厂得到sqlsession
        SqlSession sqlsession = sessionFactory.openSession();
        //通过sqlsession操作数据库,第一个参数是User.xml的方法，第二参数是需要传入的值

        List users =  sqlsession.selectList("test.findUserByName", "胖");
        System.out.println(users);
        
        sqlsession.close();
    }
    
    @Test
    public void testinsertuser() throws IOException {
        String resource = "SqlMapConfig.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        //创建SqlsessionFactory
        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        //通过工厂得到sqlsession
        SqlSession sqlsession = sessionFactory.openSession();
        //通过sqlsession操作数据库,第一个参数是User.xml的方法，第二参数是需要传入的值
        
        User test = new User();
        test.setName("傻强");
        test.setAddress("广州");

        sqlsession.insert("test.addUser",test);
    
        sqlsession.commit();
        System.out.println(test.getId());
        sqlsession.close();
    }
    
    @Test
    public void testdeletuserbyid() throws IOException {
        String resource = "SqlMapConfig.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        //创建SqlsessionFactory
        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        //通过工厂得到sqlsession
        SqlSession sqlsession = sessionFactory.openSession();
        //通过sqlsession操作数据库,第一个参数是User.xml的方法，第二参数是需要传入的值
        
        sqlsession.delete("test.deleteUserById",5);
    
        sqlsession.commit();
        sqlsession.close();
    }
    
    @Test
    public void testupdateuser() throws IOException {
        String resource = "SqlMapConfig.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        //创建SqlsessionFactory
        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        //通过工厂得到sqlsession
        SqlSession sqlsession = sessionFactory.openSession();
        //通过sqlsession操作数据库,第一个参数是User.xml的方法，第二参数是需要传入的值
        
        User test = sqlsession.selectOne("test.findUserById", 3);
        test.setName("冲锋舟");
        
        sqlsession.update("test.updateUser", test);
    
        sqlsession.commit();
        sqlsession.close();
    }
    

}

PART_THREE:使用dao来实现CRUD操作
1.dao文件

image.png

2.UserDao.java

package dao;

import entiy.User;

public interface UserDao {
    
    public User selectUserById(int id);

}

3.UserDaoImpl.java

package dao;

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;

import entiy.User;

public class UserDaoImpl implements UserDao {
    
    private SqlSessionFactory sqlSessionFactory;
    
    public UserDaoImpl(SqlSessionFactory sqlSessionFactory) {
        this.sqlSessionFactory = sqlSessionFactory;
    }

    @Override
    public User selectUserById(int id) {
        SqlSession sqlsession = sqlSessionFactory.openSession();
        User user = sqlsession.selectOne("test.findUserById", id);
        return user;
    }
}

备注：SqlSessionFactory是单线程的以节约资源，SqlSession是多线程的，因为其线程不安全。

PART_FOUR:使用Mapper（类似dao只是不用写实现类）来实现CRUD操作
开发规范：

1、在mapper.xml中namespace等于mapper接口地址
2、mapper.java接口中的方法名和mapper.xml中statement的id一致
3、mapper.java接口中的方法输入参数类型和mapper.xml中statement的parameterType指定的类型一致。
4、mapper.java接口中的方法返回值类型和mapper.xml中statement的resultType指定的类型一致。

1.文件结构

2. UserMapper.xml

    
        
        
    
        select * from t_user where id =#{value}
    
    
    
    
        select * from t_user where name like '%${value}%'
    
    
    
    
        
        SELECT LAST_INSERT_ID()
        
        
        
        insert into t_user (name,address) values (#{name},#{address})
    
    
    
    
        delete from t_user where id =#{id}
    
    
    
    
        update t_user set name=#{name},address=#{address} where id=#{id}
    
    
    
    
        select * from t_user 
        
            
                
                    and address = #{usercustom.address}
                   
            
        
        
    
    
    
    
        
        
    
    
    
    
        select id id_,name name_ from t_user where id = #{id}
    

3.UserMapper.java(这个名字必须和对应的xml相同)

package Mapper;

import java.util.List;

import entiy.User;
import entiy.UserCustom;
import entiy.UserQueryVo;

public interface UserMapper {
    
    public User findUserById(int id);
    
    public List findUserByName(String name);
    
    public void addUser(User user);
    
    public void deleteUserById(int id);
    
    public List findUserList(UserQueryVo userQueryVo);
    
    public List findUserResultMap(int id);

}

4.测试类

package 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 org.junit.jupiter.api.Test;

import Mapper.UserMapper;
import entiy.User;
import entiy.UserCustom;
import entiy.UserQueryVo;

public class mapperTest {
    //mapper查询id用户
    @Test
    public void testMapper() throws IOException {
        String resource = "SqlMapConfig.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        //创建SqlsessionFactory
        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        
        SqlSession sqlSession = sessionFactory.openSession();
        
        UserMapper usermapper = sqlSession.getMapper(UserMapper.class);
        User test = usermapper.findUserById(2);
        System.out.println(test);
    }
    
    //mapper名字查询用户集
    @Test
    public void testfindbyname() throws IOException {
        String resource = "SqlMapConfig.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        //创建SqlsessionFactory
        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        
        SqlSession sqlSession = sessionFactory.openSession();
        
        UserMapper usermapper = sqlSession.getMapper(UserMapper.class);
        List users = usermapper.findUserByName("胖");
        System.out.println(users);
    }
    
    //mapper用户综合查询
        @Test
        public void testfindList() throws IOException {
            String resource = "SqlMapConfig.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            //创建SqlsessionFactory
            SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
            
            SqlSession sqlSession = sessionFactory.openSession();
            
            UserQueryVo userQueryVo = new UserQueryVo();
            UserCustom userCustom = new UserCustom();
            userCustom.setAddress("珠海");
            userQueryVo.setUsercustom(userCustom);
            System.out.println(userQueryVo.getUsercustom().getAddress());
            
            UserMapper usermapper = sqlSession.getMapper(UserMapper.class);
            List userCustoms = usermapper.findUserList(userQueryVo);
            System.out.println(userCustoms);
        }
        
    //resultMap字段查询
        @Test
        public void testfindUserResultMap() throws IOException {
            String resource = "SqlMapConfig.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            //创建SqlsessionFactory
            SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
            
            SqlSession sqlSession = sessionFactory.openSession();
            
            UserMapper usermapper = sqlSession.getMapper(UserMapper.class);
            List users = usermapper.findUserResultMap(2);
            System.out.println(users);
        }
}