Question

我有一个允许将文件上传到服务器的应用程序。进度条显示上传进度。上传代码如下：

try{
                 // open a URL connection to the Servlet
                 FileInputStream fileInputStream = new FileInputStream(sourceFile);
                 int lengthOfFile = (int) sourceFile.length();
                 URL url = new URL(server_url);

                // Open a HTTP  connection to  the URL
                conn = (HttpURLConnection) url.openConnection();
                conn.setDoInput(true); // Allow Inputs
                conn.setDoOutput(true); // Allow Outputs
                conn.setUseCaches(false); // Don't use a Cached Copy
                conn.setChunkedStreamingMode(1024); // to prevent crashes due to large files
                conn.setRequestMethod("POST");
                conn.setRequestProperty("Connection", "Keep-Alive");
                conn.setRequestProperty("ENCTYPE", "multipart/form-data");
                conn.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);
                conn.setRequestProperty("uploaded_file", fileName);

                dos = new DataOutputStream(conn.getOutputStream());

                dos.writeBytes(twoHyphens + boundary + lineEnd);
                dos.writeBytes("Content-Disposition: form-data; name=\"uploaded_file\";filename=\""
                                + fileName + "\"" + lineEnd);

                dos.writeBytes(lineEnd);

                // create a buffer of  maximum size
                bytesAvailable = fileInputStream.available();

                bufferSize = Math.min(bytesAvailable, maxBufferSize);
                buffer = new byte[bufferSize];

                // read file and write it into form...
                bytesRead = fileInputStream.read(buffer, 0, bufferSize);
                int total = 0;
                while (bytesRead > 0) {

                    dos.write(buffer, 0, bufferSize);
                    bytesAvailable = fileInputStream.available();
                    bufferSize = Math.min(bytesAvailable, maxBufferSize);
                    bytesRead = fileInputStream.read(buffer, 0, bufferSize);
                    total += bytesRead;
                    publishProgress("" + (int) ((total * 100) / lengthOfFile));

                }

                // send multipart form data necesssary after file data...
                dos.writeBytes(lineEnd);
                dos.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);

                // Responses from the server (code and message)
                serverResponseCode = conn.getResponseCode();
                String serverResponseMessage = conn.getResponseMessage();

                Log.i("uploadFile", "HTTP Response is : "
                        + serverResponseMessage + ": " + serverResponseCode);

// ...

上传效果很好，但是进度条显示了一个怪异的行为：它达到某个值（例如14％），然后返回零，然后再次上升到某个值，依此类推。在某个时候，它只会卡住，直到上传完成并且该栏被取消。我想这与读取文件的方式有关。请注意，如果没有conn.setChunkedStreamingMode(1024);行，也会发生同样的情况。如何使其正常工作？

用于文件上传的Android进度栏无法正常运行

0 个答案: