Mybatis基于代理 Dao 实现 CRUD 操作

我不是女神ヾ 2023-07-18 09:43 103阅读 0赞

#### 编写实体类User ####

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;
        }
    }

#### **在持久层IUserDao接口中添加**CRUD **方法** ####

public interface IUserDao { 
        List<User> findAll();
        void saveUser(User user);
        void updateUser(User user);
        void deleteUser(Integer userId);
        User findById(Integer userId);

#### **在用户的映射配置文件IUserDao.xml中配置** ####

<?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="dao.IUserDao">
        <select id="findAll" resultType="domain.User">
            select * from user;
        </select>
        <insert id="saveUser" parameterType="domain.User">
            <selectKey keyProperty="id" keyColumn="id" resultType="int" order="AFTER">
                select last_insert_id();
            </selectKey>
            insert into user (username,address,sex,birthday)values(#{username},#{address},#{sex},#{birthday});
        </insert>
        <update id="updateUser" parameterType="domain.User">
            update user set username=#{username},address=#{address},sex=#{sex},birthday=#{birthday} where id=#{id};
        </update>
        <delete id="deleteUser" parameterType="Integer">
            delete from user where id=#{id};
        </delete>
        <select id="findById" parameterType="INT" resultType="domain.User">
            select * from user where id=#{id};
        </select>

#### 添加测试类中的增删改查测试方法 ####

public class MybatisTest { 
        private InputStream in;
        private SqlSession sqlSession;
        private IUserDao userDao;
        @Before
        public void init()throws Exception{ 
            in= Resources.class.getResourceAsStream("/SqlMapConfig.xml");
            SqlSessionFactory factory=new SqlSessionFactoryBuilder().build(in);
            sqlSession=factory.openSession();
            userDao=sqlSession.getMapper(IUserDao.class);
        }
        @After
        public void destroy()throws Exception{ 
            sqlSession.commit();
            sqlSession.close();
            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("mybatis last insertid");
            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(10);
            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(10);
        }
    
        @Test
        public void testFindone() { 
            User user=userDao.findById(28);
            System.out.println(user);
        }

基 本 类 型 和 String 我 们 可 以 直 接 写 类 型 名 称 ， 也 可 以 使 用 包 名 . 类 名 的 方 式 ， 例 如 ：

java.lang.String。

实体类类型，目前我们只能使用全限定类名。

#### 编写 QueryVo 实体类 ####

public class QueryVo { 
        private User user;
    
        public User getUser() { 
            return user;
        }
    
        public void setUser(User user) { 
            this.user = user;
        }
    }

#### 在持久层接口中加入代码 ####

List<User> findByName(String username);
        int findTotal();
        List<User> findUserByVo(QueryVo vo);

#### 在配置文件中添加以下配置 ####

<select id="findByName" parameterType="string" resultType="domain.User">
            select * from user where username like #{username};
        </select>
        <select id="findTotal" resultType="int">
            select count(id) from user;
        </select>
        <select id="findUserByVo" parameterType="domain.QueryVo" resultType="domain.User">
            select * from user where username like #{user.username};
        </select>

#### **测试包装类:查询所有、模糊查询** ####

@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);
        }
    
        @Test
        public void testFindByVo() { 
            QueryVo vo = new QueryVo();
            User user=new User();
            user.setUsername("%王%");
            List<User> users=userDao.findUserByVo(vo);
            for (User u : users) { 
                System.out.println(u);
            }
        }

扫描二维码  
获取更多精彩  
关注程序员老刘  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpdXp1b3Bpbmc_size_16_color_FFFFFF_t_70_pic_center]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpdXp1b3Bpbmc_size_16_color_FFFFFF_t_70_pic_center]: /images/20230528/51eb6684b1fd48fcae4ec469865983aa.png