如何从Java中实现图像数据的表象

嘿,我已经试过研究如何从Java发布数据,而且似乎没有什么我想做的。基本上,有一种将图像上传到服务器的形式,而我想要做的是将图像发布到同一个服务器——但从Java。它还需要有正确的参数名(无论表单输入的名称是什么)。我还想返回这个方法的响应。

我搞不懂为什么这件事这么难找到,因为这件事似乎很基本。

编辑----添加的代码

基于Balusc向我展示的一些东西,我创建了以下方法。它仍然不起作用,但它是我迄今为止获得的最成功的东西(似乎向另一台服务器发布了一些内容,并返回某种响应-但我不确定是否正确地得到了响应):

edit2——根据balusc的反馈添加到代码中

edit3——发布基本有效的代码, 但似乎有问题 :

 ....

 FileItemFactory factory = new DiskFileItemFactory();

 // Create a new file upload handler
 ServletFileUpload upload = new ServletFileUpload(factory);

 // Parse the request
 List<FileItem> items = upload.parseRequest(req);

 // Process the uploaded items
 for(FileItem item : items) {
     if( ! item.isFormField()) {
         String fieldName = item.getFieldName();
         String fileName = item.getName();
         String itemContentType = item.getContentType();
         boolean isInMemory = item.isInMemory();
         long sizeInBytes = item.getSize();

         // POST the file to the cdn uploader
         postDataRequestToUrl("<the host im uploading too>", "uploadedfile", fileName, item.get());

     } else {
         throw new RuntimeException("Not expecting any form fields");
     }
 }

....

// Post a request to specified URL. Get response as a string.
public static void postDataRequestToUrl(String url, String paramName, String fileName, byte[] requestFileData) throws IOException {
 URLConnection connection=null;

 try{
     String boundary = Long.toHexString(System.currentTimeMillis()); // Just generate some unique random value.
     String charset = "utf-8";

     connection = new URL(url).openConnection();
     connection.setDoOutput(true);
     connection.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary);
     PrintWriter writer = null;
     OutputStream output = null;
     try {
         output = connection.getOutputStream();
         writer = new PrintWriter(new OutputStreamWriter(output, charset), true); // true = autoFlush, important!

         // Send binary file.
         writer.println("--" + boundary);
         writer.println("Content-Disposition: form-data; name=\""+paramName+"\"; filename=\"" + fileName + "\"");
         writer.println("Content-Type: " + URLConnection.guessContentTypeFromName(fileName));
         writer.println("Content-Transfer-Encoding: binary");
         writer.println();

         output.write(requestFileData, 0, requestFileData.length);
         output.flush(); // Important! Output cannot be closed. Close of writer will close output as well.

         writer.println(); // Important! Indicates end of binary boundary.

         // End of multipart/form-data.
         writer.println("--" + boundary + "--");
     } finally {
         if (writer != null) writer.close();
         if (output != null) output.close();
     }

     //*  screw the response

     int status = ((HttpURLConnection) connection).getResponseCode();
     logger.info("Status: "+status);
     for (Map.Entry<String, List<String>> header : connection.getHeaderFields().entrySet()) {
         logger.info(header.getKey() + "=" + header.getValue());
     }

 } catch(Throwable e) {
     logger.info("Problem",e);
 } 

}

我可以看到这个代码在上传文件,但是只有 之后 我把猫关了。这让我相信我会留下某种联系。

这是有效的!