Question

我正在使用GWT-RPC开发GWT客户端 - 服务器webapp;大多数情况下似乎工作正常，但我遇到了一个错误，检索IsSerializable类型的ArrayList。

以下是服务器端方法的代码：

    public GWTInvoiceList listInvoices(String enterpriseID, int selection) {
    try{
        logger.log("ISI getting a listy of invoices "+selection);
        PlataccsUser pxuser =  (PlataccsUser) getSession().getAttribute(PlataccsConstants.USER);
        Enterprise enterprise= pxuser.getEnterprise(enterpriseID);
        Clerk clerk= pxuser.getClerk(enterprise);
         int i=0;
         List<Invoice> invoices =Invoice.getInvoices(enterprise, clerk, selection);
         GWTInvoiceList gwinvoices = new GWTInvoiceList();
         Iterator<Invoice> it = invoices.iterator();
         while (it.hasNext()){
             Invoice invoice = it.next();
             logger.log("ISI-listInvoices converting invoice "+invoice.getSystemInvoiceNumber());
             gwinvoices.add(convert(invoice, clerk));
         }
         logger.log("ISI-lI, the invoice list is now ready and it lists "+gwinvoices.size()+" invoices");
        return gwinvoices;
    }catch(Exception px){
        logger.log("ISI propblem getting invoice list", px);
        return null;
    }
}

此代码执行时不会抛出任何异常。 GWTInvoiceList返回类型是ArrayList的简单包装器，并且已知GWTInvoice类型在其他调用中成功序列化。客户端代码是：

    public InvoiceList(PlataxTabPanel parent, GWTEnterprise gwtEnterprise, int list_selection_type) {
    super(parent, gwtEnterprise.getName());
     topLabel.setText("List of Invoices");
     subHeader.setText("blah blah");
     invoiceService.listInvoices(gwtEnterprise.getEnterpriseID(), list_selection_type, invoiceListCallBack);

     //table headers:
     table.setWidget(0, 0, new ColumnHeaderLabel(LabelText.LIST_INVOICE_NUMBER_HEADER));
     table.setWidget(0, 1, new ColumnHeaderLabel(LabelText.LIST_INVOICE_CUSTOMER_HEADER));
     table.setWidget(0, 2, new ColumnHeaderLabel(LabelText.LIST_INVOICE_VALUE_DATE_HEADER));
     table.setWidget(0, 3, new ColumnHeaderLabel(LabelText.LIST_INVOICE_DUE_DATE_HEADER));
     table.setWidget(0, 4, new ColumnHeaderLabel(LabelText.LIST_INVOICE_STATUS_HEADER));
     table.setWidget(0, 5, new MoneyColumnHeaderLabel(LabelText.LIST_INVOICE_NET_HEADER));
     table.setWidget(0, 6, new MoneyColumnHeaderLabel(LabelText.LIST_INVOICE_TAX_HEADER));
     table.setWidget(0, 7, new MoneyColumnHeaderLabel(LabelText.LIST_INVOICE_TOTAL_HEADER));

}


final AsyncCallback<GWTInvoiceList> invoiceListCallBack= new AsyncCallback<GWTInvoiceList>(){
    @Override
    public void onSuccess(GWTInvoiceList invoices){
    Iterator<GWTInvoice> gwit = invoices.iterator();
     int row = 1;
     while(gwit.hasNext()){
         GWTInvoice gwinvoice = gwit.next();
         table.setWidget(row, 0, new Label(gwinvoice.getUserno()));
         table.setWidget(row, 1, new Label(gwinvoice.getCustomer().getName()));
         table.setWidget(row, 2, new Label(DateTimeFormat.getFormat(DateFormats.SHORT_DATE_FORMAT).format(gwinvoice.getValueDate())));
         table.setWidget(row, 3, new Label(DateTimeFormat.getFormat(DateFormats.SHORT_DATE_FORMAT).format(gwinvoice.getDueDate())));
         table.setWidget(row, 4, new Label(gwinvoice.getStatus()));
         table.setWidget(row, 5, new MoneyLabel(gwinvoice.getNet()));
         table.setWidget(row, 6, new MoneyLabel(gwinvoice.getTax()));
         table.setWidget(row, 7, new MoneyLabel(gwinvoice.getGross()));
         row++;
     }
    }

    @Override
    public void onFailure(Throwable cause) {
         //Debugging code

        StackTraceElement[] st = cause.getStackTrace();
       String error = "get invoice list failed\n";

       error = error+cause.getClass().getName()+"\n";
       if (cause instanceof StatusCodeException){
            StatusCodeException sce=(StatusCodeException) cause;
            int sc = sce.getStatusCode();
            error=error+"Status Code:"+ sc+"\n";
        }
       for (int i=0; i<st.length; i++){
           error = error + st[i].toString()+ "\n";
       }
        Window.alert(error);
    }
};

调用始终以500状态代码失败，因此会触发AsyncCallback内部类的OnFailure方法。

我有点不知道为什么因为没有服务器端错误。

问题是服务器端的序列化问题，但我无法看到它来自何处。我已经重写OnAfterResponseSerialized来探测事物并且它没有被调用 - （它由同一服务实现类中的其他方法调用，因此探测工作正常）。       从javadocs，processCall（）应该抛出一个SerializationException。我需要抓住它，看看发生了什么。

Answer 1

GWTInviceList代码是什么样的？

我猜你没有GWTInvoiceList类的无参数构造函数。

Answer 2

此代码：

 /**
 * catches the SerializationException for forensic examination.
 */
@Override
public String processCall(String payload) throws SerializationException{
    try{
        return super.processCall(payload);
    }catch(SerializationException se){
        logger.log("Xservlet serialisation excption", se);
        throw se;
    }
}

添加到服务实现类中捕获SerializationException，以便我可以跟踪异常对象。

检索ArrayList时GWT-RPC原因不明的500status错误

2 个答案: