【Mybatis学习路线】day02mybatis的增删改查操作

1.mybatis的增加操作

1.配置文件

<select id="selectUser" resultType="net.xyz.entiy.User">    
	  select * from user where id = #{id}  
	</select> 

2.UserDao层

  public int addUser(User user) throws IOException {
    	SqlSession sqlSession=MybatisUtil.getSession();    	
    	int result=sqlSession.insert("net.xyz.entiy.UserMapper.addUser",user);
    	sqlSession.commit();
    	sqlSession.close();
    	return result;
    }

3.Test操作

//向数据库中添加一个用户
		User user=new User();
		user.setUsername("风清扬");
	    user.setUserage(12);
	    try {
			System.out.println(userDao.addUser(user));
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

2.mybatis的删除操作

1.配置文件

<delete id="deleteUser" parameterType="net.xyz.entiy.User">
	    delete from user where id=#{id}
	</delete>

2.UserDao层

 public int deleteUser(User user) throws IOException {
    	SqlSession sqlSession=MybatisUtil.getSession();    	
    	int result=sqlSession.insert("net.xyz.entiy.UserMapper.deleteUser",user);
    	sqlSession.commit();
    	sqlSession.close();
    	return result;
    }

3.Test

 //4.根据用户id删除用户
		try {
			User user =userDao.selectUserById(4);
			System.out.println(userDao.deleteUser(user));
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

3.Mybatis的修改操作

从数据库中修改一条记录
1.配置文件

<update id="updateUser" parameterType="net.xyz.entiy.User" >
	   update user set username = #{username},userage=#{userage} where id=#{id}
	</update>

2.UserDao层

 public int updateUser(User user) throws IOException {
        SqlSession sqlSession=MybatisUtil.getSession();    	
    	int result=sqlSession.insert("net.xyz.entiy.UserMapper.updateUser",user);
    	sqlSession.commit();
    	sqlSession.close();
    	return result;
    }

3.Test操作

	    User user;
		try {
			user = userDao.selectUserById(2);
			 user.setUsername("陆小果");
			 user.setUserage(123);
			 System.out.println(userDao.updateUser(user));
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

4.mybatis的查询操作

1.配置文件

<select id="selectUser" resultType="net.xyz.entiy.User">    
	  select * from user where id = #{id}  
	</select> 

2.UserDao层

public User selectUserById(int id) throws IOException {
		SqlSession sqlSession=MybatisUtil.getSession();
		User user=sqlSession.selectOne("net.xyz.entiy.UserMapper.selectUser", id);
		sqlSession.close();
		return user;
	}

3.Test操作

//1.根据用户id查询用户
		UserDao userDao=new UserDao();
		try {
			User user=userDao.selectUserById(2);
			System.out.println(user);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

5.Mybatis中查询所有用户

1.配置文件

<select id="selectAllUser" resultType="net.xyz.entiy.User">
	   select * from user
	</select>

2.UserDao层

 public List<User> selectAllUser() throws IOException{
    	SqlSession sqlSession=MybatisUtil.getSession();    	
    	List<User> users=sqlSession.selectList("net.xyz.entiy.UserMapper.selectAllUser");
    	sqlSession.commit();
    	sqlSession.close();
    	return users;
    }

3.Test操作

try {
					List<User> users=userDao.selectAllUser();
					for(User user:users) {
						System.out.println(user.toString());
					}
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}