java - JAXB:类转换异常，但类具有相同的名称

Question

我有一个有趣的问题。

当我启动 glassfish 服务器时，一切正常。但是，我更改了一些代码并发布了服务器，然后运行我的客户端 (SistemGirisClientKullaniciDogrula)。应用程序抛出此异常:

java.lang.ClassCastException: tr.com.app.Kullanici cannot be cast to tr.com.app.Kullanici.

Interesting part is, after the Glassfish server restart, application works fine.

I am using restlet-spring-hibernate. And I am also using JAXB (org.restlet.ext.jaxb.jar) for converting XML to Java objects. My application server is Glassfish v3.0

detail for congiguration

• restlet 2.0.5
• spring 3.0.5
• hibernate 3.3.2
• glassfish v3.0

client class(Just for test)

import java.io.IOException;

import org.restlet.Client;
import org.restlet.Request;
import org.restlet.Response;
import org.restlet.data.MediaType;
import org.restlet.data.Method;
import org.restlet.data.Protocol;
import org.restlet.ext.jaxb.JaxbRepresentation;

public class SistemGirisClientKullaniciDogrula {

    public static void main(String[] Args) throws IOException {

        String url = "http://localhost:8080/Project/sistemgirisws";

        Client client = new Client(Protocol.HTTP);

        Kullanici kullanici = new Kullanici();
        kullanici.setKodu("1");

        JaxbRepresentation<Kullanici> jaxbRepresentationSendingKullanici= new JaxbRepresentation<Kullanici>(MediaType.APPLICATION_XML, kullanici);

        Request request = new Request(Method.GET, url, jaxbRepresentationSendingKullanici);
        Response response = client.handle(request);

        JaxbRepresentation<Kullanici> kullaniciResponse = new JaxbRepresentation<Kullanici>(response.getEntity(), Kullanici.class);
        kullanici = kullaniciResponse.getObject();

        System.out.println("kullanici id : " + kullanici.getId());
    }
}

网络服务

public class ProjectWebService {

/**
 * 
 * @param representation
 * @return
 */
@Get
public Representation getKullanici(Representation representation) {

    JaxbRepresentation<Kullanici> jaxbRepresentation = new JaxbRepresentation<Kullanici>(representation, Kullanici.class);

    Kullanici kullanici = new Kullanici();

    try {

        kullanici = jaxbRepresentation.getObject(); //THIS LINE THROW java.lang.classCastException tr.com.app.Kullanici cannot be cast to tr.com.app.Kullanici.

    } catch (IOException e) {
        e.printStackTrace();
    }

    try {

        kullanici = sistemGirisBusinessManager.kullaniciDogrula(kullanici);

        getResponse().setStatus(Status.SUCCESS_OK);
        return new JaxbRepresentation<Kullanici>(MediaType.APPLICATION_XML, kullanici);

    } catch (Exception exception) {

        exception.printStackTrace();
        getResponse().setStatus(Status.CLIENT_ERROR_EXPECTATION_FAILED);
        return new JaxbRepresentation<MesajList>(MediaType.APPLICATION_XML, sistemGirisBusinessManager.getMesajList());

    }
}
}

有人知道问题出在哪里吗？

Answer 1

这可能是类加载问题。在 Java 中，如果两个类加载器加载了同一个类，则将其视为两个不同的类。在这种情况下，您的转换将失败，因为在 JVM 看来，您正在将一种类型转换为不在继承树中的另一种类型。

一定会发生的事情是，当您修改您的类时，它会被加载到一个不同的类加载器中，而 Web 服务使用的是原始类加载器。