Java 删除时删除分离的实例错误

当我试图从REST控制器中删除下面的Customer对象时，出现“删除分离的实例”异常

日志：

org.springframework.dao.InvalidDataAccessApiUsageException: Removing a detached instance com.test.model.Customer#1750; nested exception is java.lang.IllegalArgumentException: Removing a detached instance com.test.model.Customer#1750

@Entity
public class Customer{

@Id
private Long id;

@OneToOne(fetch = FetchType.EAGER)
@JoinColumn(name="COUNTRY_ID", nullable=false)
private Country country;

// other stuff with getters/setters

}

@Controller
@RequestMapping("/shop/services/customers")
public class CustomerRESTController {

   /**
     * Deletes a customer
     */
    @RequestMapping( value="/{id}", method=RequestMethod.DELETE)
    @ResponseStatus(HttpStatus.NO_CONTENT)
    public void deleteCustomer(@PathVariable Long id, HttpServletRequest request, HttpServletResponse response) throws Exception {

        Customer customer = customerService.getById(id);
        if(customer != null){
            customerService.delete(customer);
        }else{
            response.sendError(503, "No Customer found for ID : " + id);
        }
    }

    // other stuff
}

域：

org.springframework.dao.InvalidDataAccessApiUsageException: Removing a detached instance com.test.model.Customer#1750; nested exception is java.lang.IllegalArgumentException: Removing a detached instance com.test.model.Customer#1750

@Entity
public class Customer{

@Id
private Long id;

@OneToOne(fetch = FetchType.EAGER)
@JoinColumn(name="COUNTRY_ID", nullable=false)
private Country country;

// other stuff with getters/setters

}

@Controller
@RequestMapping("/shop/services/customers")
public class CustomerRESTController {

   /**
     * Deletes a customer
     */
    @RequestMapping( value="/{id}", method=RequestMethod.DELETE)
    @ResponseStatus(HttpStatus.NO_CONTENT)
    public void deleteCustomer(@PathVariable Long id, HttpServletRequest request, HttpServletResponse response) throws Exception {

        Customer customer = customerService.getById(id);
        if(customer != null){
            customerService.delete(customer);
        }else{
            response.sendError(503, "No Customer found for ID : " + id);
        }
    }

    // other stuff
}

休息控制器：

org.springframework.dao.InvalidDataAccessApiUsageException: Removing a detached instance com.test.model.Customer#1750; nested exception is java.lang.IllegalArgumentException: Removing a detached instance com.test.model.Customer#1750

@Entity
public class Customer{

@Id
private Long id;

@OneToOne(fetch = FetchType.EAGER)
@JoinColumn(name="COUNTRY_ID", nullable=false)
private Country country;

// other stuff with getters/setters

}

@Controller
@RequestMapping("/shop/services/customers")
public class CustomerRESTController {

   /**
     * Deletes a customer
     */
    @RequestMapping( value="/{id}", method=RequestMethod.DELETE)
    @ResponseStatus(HttpStatus.NO_CONTENT)
    public void deleteCustomer(@PathVariable Long id, HttpServletRequest request, HttpServletResponse response) throws Exception {

        Customer customer = customerService.getById(id);
        if(customer != null){
            customerService.delete(customer);
        }else{
            response.sendError(503, "No Customer found for ID : " + id);
        }
    }

    // other stuff
}

我正在从数据库中获取客户对象，但仍处于休眠状态。

---

任何建议？？？

在当前会话（或更好的事务）中分离实体。因为您在Spring中，所以使用for事务行为是很常见的。有了这样的Hibernate，提交后会自动清除持久性上下文（当用作JPA解决方案时也是如此）

通常Hibernate不会清除会话的持久性上下文，因此在提交后实体通常不会分离。（这在分布式环境中是不安全的，但如果仅使用Hibernate访问数据库并使用像Ehcache这样的分布式缓存，则可以保存）

解决方案：

session.merge（object）

将实体重新附加到当前会话对象的持久性上下文

它实际上不是合并，而是重新连接，如果Hibernate不确定实体的当前状态是否反映了正确的数据库缓存，它将重新加载实体。（并添加版本属性（@version）出现时的特殊行为）

顺便说一下，Hibernate的文档说明：

将给定对象的状态复制到具有相同标识符的持久对象上。如果当前没有与会话关联的持久实例，则将加载该实例

更新

看到代码后，这看起来像是一个事务性问题。请检查您的customerService.getById（id）和customerService.delete（customer）服务调用是否导致事务提交。您需要将两者放在同一个事务中

您还可以做一件事来解决您的问题：

public void deleteCustomer(@PathVariable Long id, HttpServletRequest request, HttpServletResponse response) throws Exception {
    boolean wasDeleted = customerService.delete(id);
    if(!wasDeleted)
        response.sendError(503, "No Customer found for ID : " + id);
    }
}

---

这样您就不需要两次服务呼叫。实际上，在高级服务调用中使用hibernate实体是不典型的（但对于不同的体系结构，这可能有所不同。我没有太多地使用Spring）。

您能展示一下

customerService

的代码吗？当然……这里是：

@service（“customerService”）公共类customerService Impl{public Customer getById（Long id）{return customerDAO.getById（id）；}}

谢谢！…您的建议有效。我已将控制器中的检索和删除逻辑移动到单个服务方法。