基于简单REST的程序中的HTTP 500内部服务器错误.在从服务器接收/发送响应时,在GET和POST中混淆

Question

我是第一次使用REST服务实现基本的客户端服务器体系结构.这次我将包含更多的类和服务与共享类对象作为客户端和服务器之间的参数进行了更复杂化.我在ApacheTomcat7上运行服务器.它正在成功执行.当我运行我的客户端它给我错误:javax.ws.rs.InternalServerErrorException: HTTP 500 Internal Server Error我尝试调试我的代码,似乎我没有正确接收/发送响应.我知道在这里分享所有课程并不明智,但我别无选择,因为它浪费了我很多时间.任何帮助将不胜感激.提前致谢.

以下是我的ImageProgress课程.该类存在于服务器和客户端.

@XmlRootElement
public class ImageProgress{
    private String name;

    public ImageProgress( String image_name){
        this.name = image_name;
    }

    public String getName() {
        return name;
    }

    public void setName( String name ){
        this.name = name;
    }
}

HPCResponse是一个类,其对象将作为服务器响应返回给客户端.HPCResponse基本上会返回ImageProgress对象,它会给我预期的结果.

@XmlRootElement
public class HPCResponse
{
    private ImageProgress imgProgress;

    public ImageProgress getImgProgress() {
        return imgProgress;
    }

    public void setImgProgress(ImageProgress imgProgress) {
        this.imgProgress = imgProgress;
    }
}

以下是来自名为HpcService的服务器的服务类,它将HPCResponse的对象作为响应返回.如您所见,startAnalysing方法接受HPCInfo的对象.HPCInfo的描述也在下面给出.

@Path( "/hpc" )
@Consumes( MediaType.APPLICATION_XML )
@Produces( MediaType.APPLICATION_XML )
public class HpcService{

    public HPCInfo hpcInfo;
    public HPCResponse hpcResponse;

    @POST
    @Path( "/analyze" )
    public HPCResponse startAnalysing(HPCInfo _hpcInfo){

        System.out.println( "Started Analyzing..." );

        hpcInfo = _hpcInfo;
        hpcInfo.getImagePath();        

        hpcResponse = new HPCResponse();
        ImageProgress iProg = new ImageProgress(hpcInfo.getImagePath());
        hpcResponse.setImgProgress(iProg);

        System.out.println("Returning response...");
        return hpcResponse;
    }
}

HPCInfo类也在客户端和服务器上.HPCInfo类:

    @XmlRootElement
    public class HPCInfo
    {
        private String imagePath = "";

        public String getImagePath(){
            return imagePath;
        }

        public void setImagePath( String imagePath ){
            this.imagePath = imagePath;
        }
    }

最后,我的客户端要求HPCService.

public class TestClient {
    private static String webServiceURI = "http://localhost:8080/TestServer123";
    public static void main(String[] args) {
        String input = "ABNKidney.scn";
        ClientConfig clientConfig = new ClientConfig();
        Client client = ClientBuilder.newClient(clientConfig);
        URI serviceURI = UriBuilder.fromUri(webServiceURI).build();

        WebTarget webTarget = client.target(serviceURI);

        HPCInfo info = new HPCInfo();
        info.setImagePath(input);

        webTarget = webTarget.path("test").path("hpc").path("analyze");

        HPCResponse hResponse = webTarget.request().accept(MediaType.APPLICATION_XML).post(Entity.entity(info, MediaType.APPLICATION_XML), HPCResponse.class);
    }
}

这是我得到的完整错误说明:

javax.ws.rs.InternalServerErrorException: HTTP 500 Internal Server Error
    at org.glassfish.jersey.client.JerseyInvocation.convertToException(JerseyInvocation.java:968)
    at org.glassfish.jersey.client.JerseyInvocation.translate(JerseyInvocation.java:795)
    at org.glassfish.jersey.client.JerseyInvocation.access$500(JerseyInvocation.java:91)
    at org.glassfish.jersey.client.JerseyInvocation$2.call(JerseyInvocation.java:683)
    at org.glassfish.jersey.internal.Errors.process(Errors.java:315)
    at org.glassfish.jersey.internal.Errors.process(Errors.java:297)
    at org.glassfish.jersey.internal.Errors.process(Errors.java:228)
    at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:424)
    at org.glassfish.jersey.client.JerseyInvocation.invoke(JerseyInvocation.java:679)
    at org.glassfish.jersey.client.JerseyInvocation$Builder.method(JerseyInvocation.java:435)
    at org.glassfish.jersey.client.JerseyInvocation$Builder.post(JerseyInvocation.java:338)
    at com.TestClient.main(TestClient.java:34)

Answer 1

调试这样的事情的一种方法是创建一个简单的方法ExceptionMapper来捕获未映射的异常.当没有映射器时,异常通常会冒泡到容器级别,这只会给我们带来通用的500服务器错误(大部分时间都没什么帮助).

@Provider
public class DebugExceptionMapper implements ExceptionMapper<Exception> {

    @Override
    public Response toResponse(Exception exception) {
        exception.printStackTrace();
        return Response.serverError().entity(exception.getMessage()).build();
    } 
}

然后只需注册映射器.当您使用ImageProgress类运行简单测试时,抛出异常时,会打印堆栈跟踪,您可以看到异常消息

... ImageProgress没有no-arg默认构造函数

所以只需在ImageProgress类中添加一个默认(无参数构造函数).这是JAXB模型的要求.