java - 使用servlet和JSP上传文件时ServletFileUpload parseRequest()编译错误

Question

我正在尝试使用servlet和JSP实现图像上传。

我的 JSP 页面非常简单，只有以下形式:

<form method="post" action="${pageContext.request.contextPath}/uploader" enctype="multipart/form-data">
    <input type="file" name="file" value="Select an image..." />
    <input type="submit" value="Upload Now" />
</form>

相应的 servlet 和 servlet-mapping 在 web.xml 中描述。 .
还有我的doPost方法如下:

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    PrintWriter out = response.getWriter();

    FileItemFactory itemFactory = new DiskFileItemFactory();
    ServletFileUpload upload = new ServletFileUpload(itemFactory);

    if (!contentType.equals("image/png")) {
        out.println("Only PNG image files supported.");
        continue;
    }

    try {
        List<FileItem> items = upload.parseRequest(request); // here is an error
        for (FileItem item : items) {
            String contentType = item.getContentType();

            File uploadDir = new File(UPLOAD_DIR);
            File file = File.createTempFile("img", ".png", uploadDir);

            item.write(file);

            out.println("File uploaded.");
        }
    } catch (FileUploadException e) {
        out.println("Upload failed.");
        return;
    }
}

但是编译器在以下行中提示:List<FileItem> items = upload.parseRequest(request); :

The method parseRequest(RequestContext) in the file FileUploadBase is not applicable for the arguments (HttpServletRequest).

在答案中How to upload files to server using JSP/Servlet?此方法不会产生任何错误:

List<FileItem> items = new ServletFileUpload(new DiskFileItemFactory()).parseRequest(request);

Answer 1

如果我看到这里org.apache.commons.fileupload 请求应该是 ServletRequestContext 而不是 HttpServletRequest :

List<FileItem> items = new ServletFileUpload(new DiskFileItemFactory()).parseRequest(new ServletRequestContext(request));