JAVAEE框架技术之10-myBatis注解式开发

﹏ヽ暗。殇╰゛Y 2023-09-29 17:21 44阅读 0赞

## Mybatis注解开发 ##

注解开发只需要写mapper接口即可，无需再书写对应的xxMapper.xml映射文件

对于单表操作还是比较方便的，但对多表操作就维护起来就比较麻烦了

### 数据库准备 ###

![在这里插入图片描述][f554c6f4459749eca533b09b2a4b8877.png_pic_center]

### 添加依赖 ###

<dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <version>1.18.12</version>
      <scope>provided</scope>
    </dependency>
    
    
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.5.6</version>
    </dependency>
    
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.16</version>
    </dependency>
    
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
    </dependency>
    
    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-log4j12</artifactId>
      <version>1.6.4</version>
    </dependency>

### 核心配置文件 ###

mybatis-config.xml

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE configuration
            PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
            "http://mybatis.org/dtd/mybatis-3-config.dtd">
    <configuration>
        
        <properties resource="jdbc.properties"/>
        
        <settings>
            <setting name="mapUnderscoreToCamelCase" value="true"/>
        </settings>
    
        
        <environments default="development">
            <environment id="development">
                <transactionManager type="JDBC"/>
                <dataSource type="POOLED">
                    <property name="driver" value="${driverClass}"/>
                    <property name="url" value="${url}"/>
                    <property name="username" value="${jdbc.username}"/>
                    <property name="password" value="${jdbc.password}"/>
                </dataSource>
            </environment>
        </environments>
    
        <mappers>
            <package name="cn.yanqi.mapper"/>
        </mappers>
    
    </configuration>

### jdbc.properties ###

driverClass=com.mysql.jdbc.Driver
    url=jdbc:mysql:///mybatis
    jdbc.username=root
    jdbc.password=root

![在这里插入图片描述][7f8abc807e674d3db0ab62c25484b3bc.png_pic_center]

## 单表操作 ##

### 实体类 ###

@Data
    public class User {
        
        private Long id;
        // 用户名
        private String userName;
        // 密码
        private String password;
        // 姓名
        private String name;
        // 年龄
        private Integer age;
        // 性别，1男性，2女性
        private Integer sex;
        // 出生日期
        private Date birthday;
        // 创建时间
        private Date created;
        // 更新时间
        private Date updated;
    }

### Mapper接口 ###

/**
     * @Auther: yanqi
     * @Date:
     * @Dese:
     */
    public interface UserMapper {
        
    
        @Select("select * from tb_user where id = #{id}")
        User findById(int id);
    
        @Select("select * from tb_user")
        List<User> selectAll();
    
        @Insert("INSERT INTO tb_user(id, user_name, password, name, age, sex, birthday, created, updated) VALUES (null,#{userName},#{password},#{name},#{age},#{sex},#{birthday},#{created},#{updated})")
        void adduser(User user);
    
        @Delete("delete from tb_user where id = #{id}")
        void delete(int id);
    
        @Update("update tb_user set user_name =#{userName} ,  updated = #{updated} where id =#{id}")
        void updateuser(User user);
        
    }

### 测试 ###

/**
     * @Auther: yanqi
     * @Date:
     * @Dese:
     */
    public class UserMapperTest {
        
    
        private UserMapper userMapper;
        private SqlSession sqlSession ;
        private SqlSessionFactory sqlSessionFactory ;
    
    
        @Before
        public void setUp() throws Exception {
        
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
            sqlSession = sqlSessionFactory.openSession();
            userMapper = sqlSession.getMapper(UserMapper.class);
        }
    
        /**
         * 查询单个
         */
        @Test
        public void select() {
        
            User user = this.userMapper.findById(1);
            System.out.println(user);
    
        }
    
        /**
         * 查询所有
         */
        @Test
        public void selectAll() {
        
            List<User> users = this.userMapper.selectAll();
            for(User user : users){
        
                System.out.println(user);
            }
        }
    
        /**
         * 添加
         */
        @Test
        public void adduser() {
        
            User user = new User();
            user.setUserName("小江江");
            user.setPassword("123");
            user.setName("一燕");
            user.setAge(27);
            user.setSex(2);
            user.setBirthday(new Date());
            user.setCreated(new Date());
            user.setUpdated(new Date());
    
            this.userMapper.adduser(user);
            this.sqlSession.commit();
        }
    
        /**
         * 删除
         */
        @Test
        public void delete() {
        
            this.userMapper.delete(114);
            this.sqlSession.commit();
        }
    
        /**
         * 修改
         */
        @Test
        public void updateuser() {
        
            User user = new User();
            user.setId(118L);
            user.setUserName("哈哈2");
            user.setUpdated(new Date());
    
            this.userMapper.updateuser(user);
            this.sqlSession.commit();
        }
    }

## 一对一 ##

### 实体类 ###

/**
     * 订单表
     */
    @Data
    public class Order {
        
        private Integer id;
        private Long userId;
        private String orderNumber;
    
        private User user;
    }

### Mapper接口 ###

/**
     * @Auther: yanqi
     * @Dese: OrderMapper接口 实现一对一
     */
    public interface OrderMapper {
        
    
        /**
         * 查询订单，并且查询出下单人的信息
         * @param
         * @return
         */
        @Select("select * from tb_order where order_number = #{orderNum}")
        @Results({
        
                /*映射user
                    column:   order表中user_id外键，传递给UserMapper.findById的id
                    property: order实体类中的user字段
                 */
                @Result(
                        column = "id",
                        property ="user",
                        javaType = User.class,
                        one = @One(select = "cn.yanqi.mapper.UserMapper.findById"))
        		})
        List<Order> oneToOne(String orderNum);
    }

public interface UserMapper {
        
    
        @Select("select * from tb_user where id = #{id}")
        User findById(int id);
    }

### 测试 ###

/**
     * @Auther: yanqi
     * @Date:
     * @Dese:
     */
    public class UserMapperTest {
        
    
        private UserMapper userMapper;
        private OrderMapper orderMapper;
        private SqlSession sqlSession ;
        private SqlSessionFactory sqlSessionFactory ;
    
    
        @Before
        public void setUp() throws Exception {
        
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
            sqlSession = sqlSessionFactory.openSession();
            userMapper = sqlSession.getMapper(UserMapper.class);
            orderMapper = sqlSession.getMapper(OrderMapper.class);
    
        }
    
        /**
         * 测试一对一
         */
        @Test
        public void oneToOne(){
        
            List<Order> orders = this.orderMapper.oneToOne("20200921002");
            for(Order order : orders){
        
                System.out.println(order);
            }
        }

## 一对多 ##

### 实体类 ###

/**
     * 订单表
     * 
     */
    @Data
    public class Order {
        
        private Integer id;
        private Long userId;
        private String orderNumber;
    
        private User user;
    
    	private List<Orderdetail> orderdetails;
    }

@Data
    public class Orderdetail {
        
        private Integer id;
        private Double totalPrice;
        private Integer status;
    }

### Mapper接口 ###

/**
     * @Auther: yanqi
     * @Date:
     * @Dese:
     */
    public interface OrderMapper {
        
    
     /**
         * 查询订单，查询出下单人信息并且查询出订单详情。
         */
        @Select("select * from tb_order where order_number = #{orderNum}")
        @Results({
        
                /*映射user*/
                @Result(column = "id",
                        property ="user",
                        javaType = User.class,
                        one = @One(select = "cn.yanqi.mapper.UserMapper.findById")),
                /*映射orderdetails*/
                @Result(column = "id",
                        property = "orderdetails",
                        javaType =List.class,
                        many = @Many(select = "cn.yanqi.mapper.OrderDetailMapper.findById"))
        })
        List<Order> oneToMany(String orderNum);
    }

/**
     * @Auther: yanqi
     */
    public interface OrderDetailMapper {
        
        /**
         * 根据id查询订单详情
         * @param id
         */
        @Select("select * from tb_orderdetail where id = #{id}")
        Orderdetail findById(int id);
    }

### 测试 ###

/**
     * @Auther: yanqi
     * @Date:
     * @Dese:
     */
    public class UserMapperTest {
        
    
        private UserMapper userMapper;
        private OrderMapper orderMapper;
        private SqlSession sqlSession ;
        private SqlSessionFactory sqlSessionFactory ;
    
    
        @Before
        public void setUp() throws Exception {
        
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
            sqlSession = sqlSessionFactory.openSession();
            userMapper = sqlSession.getMapper(UserMapper.class);
            orderMapper = sqlSession.getMapper(OrderMapper.class);
    
        }
    
        /**
         * 测试一对多
         */
        @Test
        public void oneToMany(){
        
            List<Order> orders = this.orderMapper.oneToMany("20200921002");
            for(Order order : orders){
        
                System.out.println(order);
    	}

## 多对多 ##

### 实体类 ###

/**
     * 订单详情
     */
    @Data
    public class Orderdetail {
        
        private Integer id;
        private Double totalPrice;
        private Integer status;
    
        //商品信息
        private Item item;
    }

/**
     * 商品表
     */
    @Data
    public class Item {
        
        private Integer id;
        private String itemName;
        private Float itemPrice;
        private String itemDetail;
    }

### Mapper接口 ###

public interface OrderMapper {
        
           /**
         * 查询订单，查询出下单人信息并且查询出订单详情中的商品数据。
         */
        @Select("select * from tb_order where order_number = #{orderNum}")
        @Results({
        
                /*映射user*/
                @Result(column = "id",
                        property ="user",
                        javaType = User.class,
                        one = @One(select = "cn.yanqi.mapper.UserMapper.findById")),
                /*映射orderdetails*/
                @Result(column = "id",
                        property = "orderdetails",
                        javaType =List.class,
                        //查询Item商品
                        many = @Many(select = "cn.yanqi.mapper.ItemMapper.findById"))
                })
        List<Order> manyToMany(String orderNum);
        
    }

public interface ItemMapper {
        
    
        @Select("select * from tb_item where id = #{id}")
        List<Item> findById(Integer id);
        
    }

### 测试 ###

/**
         * 测试多对多
         */
        @Test
        public void manyToMany() {
        
            List<Order> orders = this.orderMapper.manyToMany("20200921002");
            for (Order order : orders) {
        
                System.out.println(order);
            }
        }

[f554c6f4459749eca533b09b2a4b8877.png_pic_center]: https://img-blog.csdnimg.cn/f554c6f4459749eca533b09b2a4b8877.png#pic_center
[7f8abc807e674d3db0ab62c25484b3bc.png_pic_center]: https://img-blog.csdnimg.cn/7f8abc807e674d3db0ab62c25484b3bc.png#pic_center