返回null或抛出异常 [英] returning null or throw exception

问题描述

我正在开发一个简单的Web服务和客户端。看到我的服务片段：

  @webService 
 public Car carData（int id）{
 try { 
 return carDAO.getCars（id）; 
} catch（NullPointerException e）{
 System.out.println（Error：+ e.getLocalizedMessage（））; 
 
} 
返回null; 
  

}

可以返回null给客户端，然后客户端应该关心null OR是否更好地Web服务处理null并抛出异常？

更新：
如何我可以返回nullpointerexception而不是返回null吗？

你会推荐什么？

谢谢

解决方案

您可以在JAX-WS Web服务中使用SOAP故障。这样，当您找不到先决条件时，您可以抛出自定义异常。客户端更好的了解发生了什么。

为此，您需要一个具有 @WebFault 注释的异常。您可以在在Java JAX-WS Web服务中使用SOAP故障和例外 - Eben Hewitt on Java 。

在用户指南»GlassFish»Metro»JAX-WS 你可以找到这个例子：

  package fromjava.server; 
 
 import javax.jws.WebService; 
 
 @WebService 
 public class AddNumbersImpl {
 / ** 
 * @param number1 
 * @param number2 
 * @return总和
 * @throws AddNumbersException如果要添加的任何数字是
 * negative。 
 * / 
 public int addNumbers（int number1，int number2）throws 
 AddNumbersException {
 if（number1< 0 || number2< 0）{
 throw新的AddNumbersException（负数不能+ 
添加！，Numbers：+ number1 +，+ number2）; 
} 
 return number1 + number2; 
} 
} 
  

异常：

  package fromjavahandler.server; 
 
 public class AddNumbersException extends Exception {
 
 String detail; 
 
 public AddNumbersException（String message，String detail）{
 super（message）; 
 this.detail = detail; 
} 
 
 public String getDetail（）{
 return detail; 
} 
} 
  

JAX-WS运行时自动生成故障。 / p>

I'm developing a simple web service and client. See my snippet of service:

 @webService
 public Car carData(int id)  {
   try {
    return carDAO.getCars(id);
    } catch (NullPointerException e) {
        System.out.println("Error: "+e.getLocalizedMessage());

    }
    return  null;

}

Is is ok to returning null to client, and then the client should take care of null OR is it better that web service take care of null and throws exception?

UPDATE: How can I return nullpointerexception instead of returning null?

What would you recommend?

Thanks

解决方案

You can use SOAP faults in JAX-WS Web Services. This way, you can throw a custom exception when the prerequisites are not found. The client has a better idea of what happened.

For that, you need an Exception with @WebFault annotation. You can find a good example in Using SOAP Faults and Exceptions in Java JAX-WS Web Services - Eben Hewitt on Java.

In the Users Guide » GlassFish » Metro » JAX-WS you can find this example:

package fromjava.server;

import javax.jws.WebService;

@WebService
public class AddNumbersImpl {
    /**
     * @param number1
     * @param number2
     * @return The sum
     * @throws AddNumbersException if any of the numbers to be added is 
     * negative.
     */
    public int addNumbers(int number1, int number2) throws 
            AddNumbersException {
        if (number1 < 0 || number2 < 0) {
            throw new AddNumbersException("Negative number cant be " +
                    "added!", "Numbers: " + number1 + ", " + number2);
        }
        return number1 + number2;
    }
}

The Exception:

package fromjavahandler.server;

public class AddNumbersException extends Exception {

    String detail;

    public AddNumbersException(String message, String detail) {
        super(message);
        this.detail = detail;
    }

    public String getDetail() {
        return detail;
    }
}

The JAX-WS runtime generate the Fault automatically.

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