从网络获取文件并发送到其他地方

Question

我认为我的代码非常有效。唯一的问题是antoherPlace/submit根本没有任何文件。

它停留在while循环中，将数据发送到dataStream，所以我认为这是正确的，但是它没有将文件发送到POST请求。

所以我认为这有问题：

// Read PDF file and send to the another place
                    InputStream in = url.openStream();

                    while((bufferLength = in.read(buffer)) != -1) {
                        dataStream.write(buffer, 0, bufferLength);
                    }
                    dataStream.flush();`

完整代码

public void loadPDF() {
		try {
			URL url = new URL("http://www.pdf995.com/samples/pdf.pdf");

			// Init
			byte[] buffer = new byte[1024];
			int bufferLength;
			
			try {
				
				URLConnection con = url.openConnection();
				
				// Content is PDF
				if(con.getContentType().equalsIgnoreCase("application/pdf")) {
										
					// Another Place submit url
					String anotherPlace = "https://anotherPlace/submit";
					
					// Send data
					HttpURLConnection conn = (HttpURLConnection) new URL(anotherPlace).openConnection();
					conn.setRequestMethod("POST");
					conn.setDoOutput(true);
					conn.setUseCaches(false);
					  // creates a unique boundary based on time stamp
			        String boundary = "===" + System.currentTimeMillis() + "===";
					conn.setRequestProperty("Content-Type","multipart/form-data; boundary=" + boundary);
					conn.setRequestProperty("User-Agent", "Test Agent");
									
					// Write File data to the stream
					DataOutputStream dataStream = new DataOutputStream(conn.getOutputStream()); 
					// Read PDF file and send to the another place
					InputStream in = url.openStream();
					
					while((bufferLength = in.read(buffer)) != -1) {
						dataStream.write(buffer, 0, bufferLength);
					}
					dataStream.flush();
					
					
					// Close connections
					rd.close();					
					in.close();	
					dataStream.close();
	
				}

任何想法可能是什么问题？