Servlets GWT文件上载表单提交POST请求无法读取文件

我尝试了文件上传，参考了GWT源文件。因为我想把它添加到不同的选项卡上，所以我为它创建了GWT页面，并在那里添加了FileUpload。 未实现入口点，因为其已在其根页面中实现。 我并没有使用onModuleLoad方法，我只是创建方法来显示元素并将其添加到FormPanel中

我能够提交POST请求，但无法在servlet上捕获文件。我在GWT端或servlet端做错了什么吗

我在GWT端使用了类似的代码

public class FormPanelExample implements Composite {

  public void FormPanelExample() {
    // Create a FormPanel and point it at a service.
    final FormPanel form = new FormPanel();
    form.setAction("/myFormHandler");

    // Because we're going to add a FileUpload widget, we'll need to set the
    // form to use the POST method, and multipart MIME encoding.
    form.setEncoding(FormPanel.ENCODING_MULTIPART);
    form.setMethod(FormPanel.METHOD_POST);

    // Create a panel to hold all of the form widgets.
    VerticalPanel panel = new VerticalPanel();
    form.setWidget(panel);

    // Create a TextBox, giving it a name so that it will be submitted.
    final TextBox tb = new TextBox();
    tb.setName("textBoxFormElement");
    panel.add(tb);

    // Create a ListBox, giving it a name and some values to be associated with
    // its options.
    ListBox lb = new ListBox();
    lb.setName("listBoxFormElement");
    lb.addItem("foo", "fooValue");
    lb.addItem("bar", "barValue");
    lb.addItem("baz", "bazValue");
    panel.add(lb);

    // Create a FileUpload widget.
    FileUpload upload = new FileUpload();
    upload.setName("uploadFormElement");
    panel.add(upload);

    // Add a 'submit' button.
    panel.add(new Button("Submit", new ClickHandler() {
      public void onClick(ClickEvent event) {
        form.submit();
      }
    }));

    // Add an event handler to the form.
    form.addSubmitHandler(new FormPanel.SubmitHandler() {
      public void onSubmit(SubmitEvent event) {
        // This event is fired just before the form is submitted. We can take
        // this opportunity to perform validation.
        if (tb.getText().length() == 0) {
          Window.alert("The text box must not be empty");
          event.cancel();
        }
      }
    });
    form.addSubmitCompleteHandler(new FormPanel.SubmitCompleteHandler() {
      public void onSubmitComplete(SubmitCompleteEvent event) {
        // When the form submission is successfully completed, this event is
        // fired. Assuming the service returned a response of type text/html,
        // we can get the result text here (see the FormPanel documentation for
        // further explanation).
        Window.alert(event.getResults());
      }
    });

    RootPanel.get().add(form);
  }
}

在Servlet端

if (!ServletFileUpload.isMultipartContent(request)) {                                 
            throw new FileUploadException("error multipart request not found");              
        }       

        DiskFileItemFactory factory = new DiskFileItemFactory();            

        ServletFileUpload upload = new ServletFileUpload(factory);

        List<FileItem> items = upload.parseRequest(request);

        if (items == null) {            
            response.getWriter().write("File not correctly uploaded");
            return;
        }

        Iterator<FileItem> iter = items.iterator();

if（！ServletFileUpload.isMultipartContent（request））{
抛出新的FileUploadException（“未找到错误多部分请求”）；
}       
DiskFileItemFactory=新的DiskFileItemFactory（）；
ServletFileUpload upload=新的ServletFileUpload（工厂）；
列表项=upload.parseRequest（请求）；
如果（items==null）{
response.getWriter（）.write（“文件未正确上载”）；
返回；
}
迭代器iter=items.Iterator（）；

当我调用iter.next（）时，它给出的错误是没有这样的elementFound异常

---

异常情况下，它似乎处于提交状态。文件未提交到servlet请求。

尝试使用邮递员调用端点，并将文件直接上载到正在运行的servlet，以确保其正常工作

我检查了我自己的代码实现，它几乎与您的完全匹配，除了面板上的FileUpload之外，我没有使用任何东西。删除文本框和列表框，这样我们就可以检查文件部分是否独立工作，然后介绍每个项目并分别测试

我发现这在服务器端更可靠

FileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload servletFileUpload = new ServletFileUpload(factory);
FileItemIterator iter = servletFileUpload.getItemIterator(request);