SpringBoot整合JPA

<dependencies>   <!--JPA-->   <dependency>     <groupId>org.springframework.boot</groupId>     <artifactId>spring-boot-starter-jdbc</artifactId>   </dependency>   <dependency>     <groupId>org.springframework.boot</groupId>     <artifactId>spring-boot-starter-data-jpa</artifactId>   </dependency>   <dependency>     <groupId>org.springframework.boot</groupId>     <artifactId>spring-boot-starter-web</artifactId>   </dependency>   <dependency>     <groupId>org.springframework.boot</groupId>     <artifactId>spring-boot-devtools</artifactId>     <scope>runtime</scope>     <optional>true</optional>
  </dependency>
  <!--mysql Drive-->
  <dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <scope>runtime</scope>
  </dependency>
  <!--lombok-->
  <dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <optional>true</optional>
  </dependency>
  <!--测试-->
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
  </dependency>
    </dependencies>

server:
  port: 8080
spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://xxxx:3306/logistics?serverTimezone=UTC
    password: root
    username: root
  jpa:
# database: MYSQL
    show-sql: true
    hibernate:
      ddl-auto: update

@Data //lombok
@Entity //声明这是一个实体类
@Table(name = "`order`") //与数据库表对应起来
@Accessors(chain = true) //链式调用（可有可无）
public class Order { 
        
    @Id // 主键id
    @GeneratedValue(strategy = GenerationType.IDENTITY) //主键类型这是数据库自增
    private Integer id;

    private String orderNumber;

    private Integer skuId;

    private String userName;
}

public interface OrderDao extends JpaRepository<Order,Integer>,JpaSpecificationExecutor<Order>{ 
        
// JpaRepository<实体类，主键类型> 基本的CRUD
// JpaSpecificationExecutor 分页多条件查询 排序等功能
}

public List<Order> listPage() { 
        
        //分页对象
        PageRequest of = PageRequest.of(0, 10);
        //构建查询条件
        Page<Order> orders = orderDao.findAll(new Specification<Order>() { 
        
            /** * * @param root 实体类 * @param query 查询对象 * @param criteriaBuilder 条件构建 * @return */
            @Override
            public Predicate toPredicate(Root<Order> root, CriteriaQuery<?> query, CriteriaBuilder criteriaBuilder) { 
        
                // between root.get("skuId").as(Integer.class)->获取skuId 字段
                Predicate skuIda = criteriaBuilder.between(root.get("skuId").as(Integer.class), 0, 10);
                // 排序
                javax.persistence.criteria.Order id = criteriaBuilder.desc(root.get("id").as(Integer.class));
                //将条件放入到Wher中
                query.where(skuIda);
                //可以指定多个排序
                query.orderBy(id);
                //给定查询条件
                return query.getRestriction();
            }
        }, of);
        List<Order> content = orders.getContent();
        return content;
    }

• 效果

public void adds() { 
        
        List<Order> orders = new ArrayList<>();
        for (int i = 0; i < 20; i++) { 
        
            Order order = new Order().setOrderNumber(String.valueOf(i))
                    .setSkuId(i)
                    .setUserName(String.valueOf(i));
            orders.add(order);
        }
        orderDao.saveAll(orders);

    }

@Test
void deleteOrder(){ 
        
    //如果数据中没有id=10的记录则会抛出异常
    orderDao.deleteById(10);
}


• 处理办法

@Test
void deleteOrder(){ 
        
    if(orderDao.existsById(10)) { 
        
        orderDao.deleteById(10);
    }
}

• 或者在dao层写出方法，加上@Transactional

public interface OrderDao extends JpaRepository<Order,Integer>,JpaSpecificationExecutor<Order>{ 
        

    @Transactional
    void deleteOrdersByIdIn(List<Integer> ids);

}

@Test
void deleteTest(){ 
        
    List<Integer> ids = new ArrayList<>();
    ids.add(59);
    ids.add(60);
    orderDao.deleteOrdersByIdIn(ids);
}


@Test
void updateTest(){ 
        
    Order order = new Order().setId(61)
            .setUserName("阿巴阿巴")
            .setOrderNumber("61")
            .setSkuId(61);
    orderDao.saveAndFlush(order);

}

• 查询

public interface OrderDao extends JpaRepository<Order,Integer>,JpaSpecificationExecutor<Order>{ 
        

    @Query(value = "select * from `order` where sku_Id > ?1",nativeQuery = true)
    List<Order> getOrderBySkuId(Integer skuId);
}

 @Test
void getSkuId(){ 
        
    List<Order> orderBySkuId = orderDao.getOrderBySkuId(17);
    System.out.println(orderBySkuId);
}


• 修改

public interface OrderDao extends JpaRepository<Order,Integer>,JpaSpecificationExecutor<Order>{ 
        
    @Transactional
    @Modifying
    @Query(value = "delete from `order` where sku_id = ?1 and user_name = ?1" ,nativeQuery = true)
    void deleteOrderBySkuIdAndUserName(Integer skuId,String userName);
}

@Test
void deleteBySkuIdAndUserName(){ 
        
    orderDao.deleteOrderBySkuIdAndUserName(7,"7");
}