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我正在为一个站点编写一个上传器类，在上传文件后，我正在读取该站点的上传响应。如果我没有阅读响应，则文件没有上传。我的代码如下，

   String charset = "UTF-8";


        File binaryFile = new File("C:\\TestVideoFile.flv");
        String boundary = Long.toHexString(System.currentTimeMillis());
        System.out.println(boundary);// Just generate some unique random value.
        String CRLF = "\r\n"; // Line separator required by multipart/form-data.
        URLConnection connection = new URL(UPLOAD_URL).openConnection();
        connection.setDoInput(true); 
        connection.setDoOutput(true);
        connection.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary);
        PrintWriter writer = null;
        try {
            OutputStream output = connection.getOutputStream();
            writer = new PrintWriter(new OutputStreamWriter(output, charset), true); // true = autoFlush, important!
            writer.append("--" + boundary).append(CRLF);
            writer.append("Content-Disposition: form-data; name=\"file\"; filename=\"" + binaryFile.getName() + "\"").append(CRLF);
            writer.append("Content-Type: " + URLConnection.guessContentTypeFromName(binaryFile.getName())).append(CRLF);
            writer.append("Content-Transfer-Encoding: binary").append(CRLF);
            writer.append(CRLF).flush();
            InputStream input = null;
            try {
                input = new FileInputStream(binaryFile);
                long filelen = binaryFile.length();
                System.out.println("Length : " + filelen);
                int dataRead = 0;
                byte[] buffer = new byte[1024];
                for (int length = 0; (length = input.read(buffer)) > 0;) {

                    output.write(buffer, 0, length);
                }
                System.out.println("Now only terminating the file write loop");
                output.flush(); // Important! Output cannot be closed. Close of writer will close output as well.
            } catch (Exception e) {
                System.out.println(e);
            } finally {
                if (input != null) {
                    try {
                        input.close();
                    } catch (IOException logOrIgnore) {
                        System.out.println(logOrIgnore);
                    }
                }
            }
            writer.append(CRLF).flush(); // CRLF is important! It indicates end of binary boundary.

            // End of multipart/form-data.
            writer.append("--" + boundary + "--").append(CRLF);

            System.out.println("Sending username");
            // Send normal param.
            writer.append("--" + boundary).append(CRLF);
            writer.append("Content-Disposition: form-data; name=\"user\"").append(CRLF);
            writer.append("Content-Type: text/plain; charset=" + charset).append(CRLF);
            writer.append(CRLF);
            writer.append(username).append(CRLF).flush();
            System.out.println("Sending password");
            writer.append("--" + boundary).append(CRLF);
            writer.append("Content-Disposition: form-data; name=\"password\"").append(CRLF);
            writer.append("Content-Type: text/plain; charset=" + charset).append(CRLF);
            writer.append(CRLF);
            writer.append(password).append(CRLF).flush();


            System.out.println("Reading response from server");

            BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            String k = "", tmp = "";
            while ((tmp = br.readLine()) != null) {
                System.out.println(tmp);
                k += tmp;
            }
            if (k.contains("Successfully")) {
                System.out.println("File Uploaded successfully into PutLocker :)");
                String downloadLink = parseResponse(k, "<link>", "</link>");
                System.out.println("Download Link : " + downloadLink);
            } else {
                System.out.println("Upload failed :(");
            }

          } catch (Exception e) {
            System.out.println(e);
        } finally {
            if (writer != null) {
                writer.close();
            }
        }

如您所见，我正在以下行中将数据写入服务器，

for (int length = 0; (length = input.read(buffer)) > 0;) {

                        output.write(buffer, 0, length);
                    }

但在此之后，我必须执行以下操作，

 BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
                String k = "", tmp = "";
                while ((tmp = br.readLine()) != null) {
                    System.out.println(tmp);
                    k += tmp;
                }

为什么我必须读取服务器的响应才能使上传成功？

有人可以解释一下吗？

提前致谢。

4

1 回答 1

2

如果您尝试向服务器发布内容并且在您完全发送消息之前连接被中断，那么服务器将停止处理不完整的请求。一旦服务器完成接收请求并且您不等待得到它的响应，那么您将永远不知道您的请求是否成功发送。因此，URLConnection 旨在等待您得到响应。

另一个原因是您可能希望先构建和配置 URLConnection，然后在需要时通过调用getInputStreamor发送它getResponseCode。您可以更好地控制希望交易发生的时间。

您不需要总是getInputStream，只需调用getResponseCode即可完成请求。但是，整个输入流仍会发送到您的代码，但它们会被丢弃。

于 2012-09-24T05:31:14.920 回答