Mybatis中的原始Dao开发和动态代理开发

痛定思痛。 2022-12-09 05:18 191阅读 0赞

### Mybatis中的原始Dao开发 和 接口动态代理开发 ###

##### 原始Dao开发方法 #####

1、UserDao接口

public interface UserDao { 
    
    	// 根据用户ID查询用户信息
    	User getUserById(Integer id);
    	
    	// 根据用户名查找用户列表
    	List<User> getUserByUserName(String name);
    	
    	// 添加用户
    	void insertUser(User user);
    }

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2、UserDaoImpl接口实现类

public class UserDaoImpl implements UserDao { 
    
    	@Override
    	public User getUserById(Integer id) { 
    		SqlSession sqlSession = SqlSessionFactoryUtils.getSqlSessionFactory().openSession();
    		User user = sqlSession.selectOne("user.getUserById", id);
    		sqlSession.close();
    		return user;
    	}
    
    	@Override
    	public List<User> getUserByUserName(String name) { 
    		SqlSession sqlSession = SqlSessionFactoryUtils.getSqlSessionFactory().openSession();
    		List<User> list = sqlSession.selectList("user.getUserByName", name);
    		sqlSession.close();
    		return list;
    	}
    
    	@Override
    	public void insertUser(User user) { 
    		SqlSession sqlSession = SqlSessionFactoryUtils.getSqlSessionFactory().openSession();
    		sqlSession.insert("user.insertUser", user);
    		sqlSession.commit();
    		sqlSession.close();
    	}
    }

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3、编写测试程序

public class UserDaoTest { 
    
    	@Test
    	public void testGetUserById() { 
    		UserDao userDao = new UserDaoImpl();
    		User user = userDao.getUserById(30);
    		System.out.println(user);
    	}
    
    	@Test
    	public void testGetUserByUserName() { 
    		UserDao userDao = new UserDaoImpl();
    		List<User> list = userDao.getUserByUserName("张");
    		for (User user : list) { 
    			System.out.println(user);
    		}
    	}
    
    	@Test
    	public void testInsertUser() { 
    		UserDao userDao = new UserDaoImpl();
    		User user = new User();
    		user.setUsername("张飞");
    		user.setAddress("深圳市");
    		user.setBirthday(new Date());
    		user.setSex("1");
    		userDao.insertUser(user);
    	}
    }

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##### 接口动态代理（官方推荐） #####

1、动态代理dao开发规则

（1）namespace必需是接口的全路径名。  
（2）接口的方法名必需与映射文件的sql id一致。  
（3）接口的输入参数必需与映射文件的parameterType类型一致。  
（4）接口的返回类型必须与映射文件的resultType类型一致。

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2、动态代理dao开发步骤

（1）创建UserMapper.xml映射文件(把原来的user.xml复制按开发规则要求修改一下)  
（2）创建UserMapper接口(把原来的UserDao.java复制按开发规则要求修改一下)  
（3）加载UserMapper.xml

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3、编写测试程序

public class UserMapperTest { 
    
    	@Test
    	public void testGetUserById() { 
    		// 加载配置得到SqlSession
    		SqlSession sqlSession = SqlSessionFactoryUtils.getSqlSessionFactory().openSession();
    		
    		// 获取代理对象
    		UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
    		
    		// 查询数据
    		User user = userMapper.getUserById(30);
    		System.out.println(user);
    		
    		// 关闭资源
    		sqlSession.close();
    	}
    
    	@Test
    	public void testGetUserByUserName() { 
    		SqlSession sqlSession = SqlSessionFactoryUtils.getSqlSessionFactory().openSession();
    		UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
    		
    		List<User> list = userMapper.getUserByName("张");
    		for (User user : list) { 
    			System.out.println(user);
    		}
    
    		sqlSession.close();
    	}
    
    	@Test
    	public void testInsertUser() { 
    		SqlSession sqlSession = SqlSessionFactoryUtils.getSqlSessionFactory().openSession();
    		UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
    		
    		User user = new User();
    		user.setUsername("张飞飞");
    		user.setAddress("深圳市");
    		user.setBirthday(new Date());
    		user.setSex("1");
    		
    		userMapper.insertUser(user);
    		
    		sqlSession.commit();
    		sqlSession.close();
    	}
    }

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