使用Servlet将图像上载到GWT项目中的服务器

我正在开发一个GWT应用程序，其中包括它的其他功能，允许用户上传图像文件并将其存储在服务器上。 到目前为止，我就是这么做的

SERVLET

public class ImageUploadService extends HttpServlet {

private static final int MAX_FILE_SIZE = 1 * 1024 * 1024;

public void doPost(HttpServletRequest request, HttpServletResponse response) {

    wlog("INFO: è partita la servlet");

    if (!ServletFileUpload.isMultipartContent(request))
        wlog("ERR: non è multipart!");
    ServletFileUpload fileUpld = new ServletFileUpload();

    try {
        wlog("INFO: itero file");
        FileItemIterator fileIt = fileUpld.getItemIterator(request);
        while (fileIt.hasNext()) {

            wlog("INFO: trovato file");
            FileItemStream fileStream = fileIt.next();
            BufferedInputStream in = new BufferedInputStream(
                    fileStream.openStream(), 4096);
            BufferedOutputStream out = new BufferedOutputStream(
                    new FileOutputStream("immagineSegnalazione.jpg"));

            byte[] buf = new byte[MAX_FILE_SIZE];
            int byteRead;
            while ((byteRead = in.read(buf, 0, MAX_FILE_SIZE)) >= 0) {
                out.write(buf, 0, byteRead);
            }
            in.close();
            out.flush();
            out.close();
        }

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

private void wlog(String s) {
    System.out.println("UPLOAD SERVLET " + s);
}
}

客户端上的模块

            [...]

        PopupPanel inserisciSegnalazionePopup = new PopupPanel();
    final FormPanel uploadForm = new FormPanel();
    uploadForm.setEncoding(FormPanel.ENCODING_MULTIPART);
    uploadForm.setMethod(FormPanel.METHOD_POST);
    inserisciSegnalazionePopup.setAutoHideEnabled(true);
    VerticalPanel holder = new VerticalPanel();
    holder.add(new Label("se puoi, allega una foto della segnalazione"));
    final FileUpload fu = new FileUpload();
    uploadForm.add(fu);
    holder.add(uploadForm);
    uploadForm.setAction(GWT.getModuleBaseURL() + "imageUpload");
    Button inviaBtn = new Button("INVIA SEGNALAZIONE");
    inviaBtn.addClickHandler(new ClickHandler() {

        @Override
        public void onClick(ClickEvent event) {
            // TODO check file is image and size and other stuff


            uploadForm.submit();
        }

    });
    holder.add(inviaBtn);

            [...]

…另外，我已经正确地对web.xml进行了所需的更改 Servlet被正确调用，方法doPost（）启动，但FileItemIterator始终为空，就好像根本没有文件一样。。 有人能猜出怎么了吗？我真的看不出哪里出了错

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提前谢谢你

我猜在你使用请求之前，请求已经被解析了。试着看一看，结果是，似乎是几乎相同的问题

Sarajog

你试过这个吗

Iterator<FileItem> iterator = upload.parseRequest(request).iterator();

Iterator Iterator=upload.parseRequest（request.Iterator（）；

解决方案是。。。

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只需将.setName（）添加到FileUpload小部件

我遵循了Sarajog的建议和你的建议，但行为完全相同..在我显示的部分代码之前从未解析请求..我尝试按照你提供给我的链接中的建议更改代码，但迭代器仍然为空。。