Mybatis 传统 DAO 层实现CRUD

偏执的太偏执、 2023-07-18 09:46 65阅读 0赞

## Mybatis 实现 DAO 的传统开发方式 ##

#### 实体类User ####

根据数据库中的属性编写代码并且生成其getter、setter与toString方法

public class User implements Serializable { 
        private Integer id;
        private String username;
        private String address;
        private String sex;
        private Date birthday;
    
        @Override
        public String toString() { 
            return "User{" +
                    "id=" + id +
                    ", username='" + username + '\'' +
                    ", address='" + address + '\'' +
                    ", sex='" + sex + '\'' +
                    ", birthday=" + birthday +
                    '}';
        }
    
        public Integer getId() { 
            return id;
        }
    
        public void setId(Integer id) { 
            this.id = id;
        }
    
        public String getUsername() { 
            return username;
        }
    
        public void setUsername(String username) { 
            this.username = username;
        }
    
        public String getAddress() { 
            return address;
        }
    
        public void setAddress(String address) { 
            this.address = address;
        }
    
        public String getSex() { 
            return sex;
        }
    
        public void setSex(String sex) { 
            this.sex = sex;
        }
    
        public Date getBirthday() { 
            return birthday;
        }
    
        public void setBirthday(Date birthday) { 
            this.birthday = birthday;
        }
    }

#### 持久层Dao接口 ####

public interface IUserDao { 
        List<User> findAll();
        void saveUser(User user);
        void updateUser(User user);
        void deleteUser(Integer userId);
        User findById(Integer userId);
        List<User> findByName(String username);
        int findTotal();
    }

#### **持久层** **Dao** **实现类** ####

public class UserDaoImpl implements IUserDao { 
        private SqlSessionFactory factory;
        public UserDaoImpl(SqlSessionFactory factory){ 
            this.factory=factory;
        }
    
        public List<User> findAll() { 
            SqlSession session=factory.openSession();
            List<User> users = session.selectList("dao.IUserDao.findAll");
            session.close();
            return users;
        }
    
        public void saveUser(User user) { 
            SqlSession session=factory.openSession();
            session.insert("dao.IUserDao.saveUser",user);
            session.commit();
            session.close();
        }
    
        public void updateUser(User user) { 
            SqlSession session=factory.openSession();
            session.update("dao.IUserDao.updateUser",user);
            session.commit();
            session.close();
        }
    
        public void deleteUser(Integer userId) { 
            SqlSession session=factory.openSession();
            session.delete("dao.IUserDao.deleteUser",userId);
            session.commit();
            session.close();
        }
    
        public User findById(Integer userId) { 
            SqlSession session=factory.openSession();
            User user = session.selectOne("dao.IUserDao.findById",userId);
            session.close();
            return user;
        }
    
        public List<User> findByName(String username) { 
            SqlSession session=factory.openSession();
            List<User> users = session.selectList("dao.IUserDao.findByName",username);
            session.close();
            return users;
        }
    
        public int findTotal() { 
            SqlSession session=factory.openSession();
            Integer count = session.selectOne("dao.IUserDao.findTotal");
            session.close();
            return count;
        }
    }

#### 编写测试类 ####

public class MybatisTest { 
        private InputStream in;
        private IUserDao userDao;
        @Before
        public void init()throws Exception{ 
            in= Resources.class.getResourceAsStream("/SqlMapConfig.xml");
            SqlSessionFactory factory=new SqlSessionFactoryBuilder().build(in);
            userDao=new UserDaoImpl(factory);
        }
        @After
        public void destroy()throws Exception{ 
            in.close();
        }
        @Test
        public void testFindAll(){ 
            List<User> users=userDao.findAll();
            for (User user : users) { 
                System.out.println(user);
            }
        }
    
        @Test
        public void testSave(){ 
            User user=new User();
            user.setUsername("dao impl user");
            user.setAddress("北京市顺义区");
            user.setSex("男");
            user.setBirthday(new Date());
            System.out.println("保存操作之前"+user);
            userDao.saveUser(user);
            System.out.println("保存操作之后"+user);
        }
    
        @Test
        public void testUpdate(){ 
            User user=new User();
            user.setId(30);
            user.setUsername("mybatis.update");
            user.setAddress("北京市顺义区");
            user.setSex("女");
            user.setBirthday(new Date());
            userDao.updateUser(user);
        }
    
        @Test
        public void testDelete() { 
            userDao.deleteUser(30);
        }
    
        @Test
        public void testFindone() { 
            User user=userDao.findById(28);
            System.out.println(user);
        }
    
        @Test
        public void testFindByName() { 
            List<User> users=userDao.findByName("%王%");
            for (User user : users) { 
                System.out.println(user);
            }
        }
    
        @Test
        public void testFindTotal() { 
            int count=userDao.findTotal();
            System.out.println(count);
        }
    
    }

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