mybatis原生dao实现和动态代理Dao实现

Love The Way You Lie 2022-05-17 12:16 182阅读 0赞

**原生dao**  
**dao接口**

package cn.itheima.dao;
    
    import java.util.List;
    
    import cn.itheima.pojo.User;
    
    public interface UserDao { 
    
        public User findUserById(Integer id);
    
        public List<User> findUserByUserName(String userName);
    }

**dao实现**

package cn.itheima.dao;
    
    import java.util.List;
    
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    
    import cn.itheima.pojo.User;
    
    public class UserDaoImpl implements UserDao { 
    
        private SqlSessionFactory sqlSessionFactory;
    
        //通过构造方法注入
        public UserDaoImpl(SqlSessionFactory sqlSessionFactory) {
            this.sqlSessionFactory = sqlSessionFactory;
        }
    
        @Override
        public User findUserById(Integer id) {
            //sqlSesion是线程不安全的,所以它的最佳使用范围在方法体内
            SqlSession openSession = sqlSessionFactory.openSession();
            User user = openSession.selectOne("test.findUserById", id);
            return user;
        }
    
        @Override
        public List<User> findUserByUserName(String userName) {
            SqlSession openSession = sqlSessionFactory.openSession();
            List<User> list = openSession.selectList("test.findUserByUserName", userName);
            return list;
        }
    
    
    }

**测试原生dao**

package mybatis0523;
    
    import java.io.InputStream;
    import java.util.List;
    
    import org.apache.ibatis.io.Resources;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    import org.junit.Before;
    import org.junit.Test;
    
    import cn.itheima.dao.UserDao;
    import cn.itheima.dao.UserDaoImpl;
    import cn.itheima.pojo.User;
    
    public class UserDaoTest { 
    
        private SqlSessionFactory factory;
    
        //作用:在测试方法前执行这个方法
        @Before
        public void setUp() throws Exception{
            String resource = "SqlMapConfig.xml";
            //通过流将核心配置文件读取进来
            InputStream inputStream = Resources.getResourceAsStream(resource);
            //通过核心配置文件输入流来创建会话工厂
            factory = new SqlSessionFactoryBuilder().build(inputStream);
        }
    
        @Test
        public void testFindUserById() throws Exception{
            //将初始化好的工厂注入到实现类中
            UserDao userDao = new UserDaoImpl(factory);
    
            User user = userDao.findUserById(1);
            System.out.println(user);
        }
    
        @Test
        public void testFindUserByUserName () throws Exception{
    
            UserDao userDao = new UserDaoImpl(factory);
    
            List<User> list = userDao.findUserByUserName("王");
            System.out.println(list);
        }
    }

**mapper接口代理**  
XX.java和XX.xml在同一个文件夹下面，然后名字也要相同  
这是使用class属性引入接口的全路径名称使用规则：  
1.接口的名称和映射文件名称除扩展名外要完全相同  
2.接口和映射文件要放在同一个目录下  
**XX.xml**  
mapper接口代理实现编写规则:

1.  映射文件中namespace要等于接口的全路径名称
2.  映射文件中sql语句id要等于接口的方法名称
3.  映射文件中传入参数类型要等于接口方法的传入参数类型
4.  映射文件中返回结果集类型要等于接口方法的返回值类型

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    
    <mapper namespace="cn.itheima.mapper.UserMapper">
    
        
        <select id="findUserById" parameterType="int" resultType="cn.itheima.pojo.User">
            select * from user where id=#{id}
        </select>
    
        
        <select id="findUserByUserName" parameterType="string" resultType="user">
            select * from user where username like '%${value}%'
        </select>
    
        
        <insert id="insertUser" parameterType="cn.itheima.pojo.User" >
            
            <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer">
                select LAST_INSERT_ID()
            </selectKey>
            insert into user (username,birthday,sex,address) values(#{username},#{birthday},#{sex},#{address})
        </insert>
    </mapper>

**XX.java**

package cn.itheima.mapper;
    
    import java.util.List;
    
    import cn.itheima.pojo.User;
    
    public interface UserMapper { 
    
        public User findUserById(Integer id);
    
        //动态代理形势中,如果返回结果集问List,那么mybatis会在生成实现类的使用会自动调用selectList方法
        public List<User> findUserByUserName(String userName);
    
        public void insertUser(User user);
    }

**XXTest.java**

package mybatis0523;
    
    import java.io.InputStream;
    import java.util.Date;
    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.Before;
    import org.junit.Test;
    
    import cn.itheima.mapper.UserMapper;
    import cn.itheima.pojo.User;
    
    public class UserMapperTest {
        private SqlSessionFactory factory;
    
        //作用:在测试方法前执行这个方法
        @Before
        public void setUp() throws Exception{
            String resource = "SqlMapConfig.xml";
            //通过流将核心配置文件读取进来
            InputStream inputStream = Resources.getResourceAsStream(resource);
            //通过核心配置文件输入流来创建会话工厂
            factory = new SqlSessionFactoryBuilder().build(inputStream);
        }
    
        @Test
        public void testFindUserById() throws Exception{
            SqlSession openSession = factory.openSession();
            //通过getMapper方法来实例化接口
            UserMapper mapper = openSession.getMapper(UserMapper.class);
    
            User user = mapper.findUserById(1);
            System.out.println(user);
        }
    
        @Test
        public void testFindUserByUserName() throws Exception{
            SqlSession openSession = factory.openSession();
            //通过getMapper方法来实例化接口
            UserMapper mapper = openSession.getMapper(UserMapper.class);
    
            List<User> list = mapper.findUserByUserName("王");
    
            System.out.println(list);
        }
    
        @Test
        public void testInsertUser() throws Exception{
            SqlSession openSession = factory.openSession();
            //通过getMapper方法来实例化接口
            UserMapper mapper = openSession.getMapper(UserMapper.class);
    
            User user = new User();
            user.setUsername("老王");
            user.setSex("1");
            user.setBirthday(new Date());
            user.setAddress("北京昌平");
    
            mapper.insertUser(user);
    
            openSession.commit();
        }
    }