android - AsyncTask 中的 ProgressDialog 中有一个线程

Question

我想上传一张图片到我的服务器。因此我已经构建了这个并发送到服务器工作得很好。但是还缺少一件事，那就是 ProgressDialog。 我尝试了很多方法，但不知道如何以正确的方式进行。 我现在在 preExecute 方法的 AsyncTask 中调用 ImageUploader.uploadFile()。

在 doInBackground 中，我必须发送一封包含照片附件的电子邮件。所以照片需要在附加到电子邮件之前上传。 那么如何做到这一点以及如何显示 ProgressDialog 呢？

这是我调用函数的方式:

       @Override
        protected void onPreExecute(){
            super.onPreExecute();
            if(isPhotoTaken()){
                ImageUploader.uploadFile(getPhotoPath(), "http://www.example.com/upload.php", Step4.this);              
            }
        }

这是我的 ImageUploader 类

    public class ImageUploader {

    private static String serverResponseMessage = "";
    private static int serverResponseCode = 0;
    private static ProgressDialog dialog;

    public static int uploadFile(final String sourceFileUri, final String serverFile, final Context context) {

        Debug.out("SourceFileUri: " + sourceFileUri);
        Debug.out("ServerFile: " + serverFile);
        Thread thread = new Thread() {
            @Override
            public void run() {
                ((Activity) context).runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        dialog = new ProgressDialog(context);
                        dialog.setCancelable(false);
                        dialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
                        dialog.setMessage("Uploading Image... Please wait!");
                        dialog.show();
                    }
                });
                String upLoadServerUri = serverFile;
                String fileName = sourceFileUri;
                HttpURLConnection conn = null;
                DataOutputStream dos = null;
                String lineEnd = "\r\n";
                String twoHyphens = "--";
                String boundary = "*****";
                int bytesRead, bytesAvailable, bufferSize;
                byte[] buffer;
                int maxBufferSize = 1 * 1024 * 1024;
                File sourceFile = new File(sourceFileUri);
                if (!sourceFile.isFile()) {
                    Log.e("uploadFile", "Source File Does not exist");
                }
                try { // open a URL connection to the Servlet
                    Debug.out("in the try");
                    FileInputStream fileInputStream = new FileInputStream(
                            sourceFile);
                    URL url = new URL(upLoadServerUri);
                    conn = (HttpURLConnection) url.openConnection(); // Open a
                                                                        // HTTP
                                                                        // connection
                                                                        // to
                                                                        // the
                                                                        // URL
                    conn.setDoInput(true); // Allow Inputs
                    conn.setDoOutput(true); // Allow Outputs
                    conn.setUseCaches(false); // Don't use a Cached Copy
                    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());
                    Debug.out("Set Properties and Datastream");
                    dos.writeBytes(twoHyphens + boundary + lineEnd);
                    dos.writeBytes("Content-Disposition: form-data; name=\"uploaded_file\";filename=\""
                            + fileName + "\"" + lineEnd);
                    dos.writeBytes(lineEnd);
                    Debug.out("Writes data");
                    bytesAvailable = fileInputStream.available(); // create a
                                                                    // buffer of
                                                                    // maximum
                                                                    // size

                    bufferSize = Math.min(bytesAvailable, maxBufferSize);
                    buffer = new byte[bufferSize];
                    Debug.out("Buffer done");
                    // read file and write it into form...
                    bytesRead = fileInputStream.read(buffer, 0, bufferSize);
                    Debug.out("Read Bytes");
                    while (bytesRead > 0) {
                        dos.write(buffer, 0, bufferSize);
                        bytesAvailable = fileInputStream.available();
                        bufferSize = Math.min(bytesAvailable, maxBufferSize);
                        bytesRead = fileInputStream.read(buffer, 0, bufferSize);
                    }

                    // send multipart form data necesssary after file data...
                    dos.writeBytes(lineEnd);
                    dos.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);
                    Debug.out("After sendData");
                    // Responses from the server (code and message)
                    serverResponseCode = conn.getResponseCode();
                    serverResponseMessage = conn.getResponseMessage();
                    Debug.out("Server Response: " + serverResponseCode);
                    Log.i("uploadFile", "HTTP Response is : "
                            + serverResponseMessage + ": " + serverResponseCode);
                    Debug.out("HTTP Response is : " + serverResponseMessage
                            + ": " + serverResponseCode);
                    // close the streams //
                    fileInputStream.close();
                    dos.flush();
                    dos.close();
                }

                catch (MalformedURLException ex) {
                    ex.printStackTrace();
                    // Toast.makeText(UploadImageDemo.this,
                    // "MalformedURLException", Toast.LENGTH_SHORT).show();
                    Log.e("Upload file to server", "error: " + ex.getMessage(),
                            ex);
                } catch (Exception e) {
                    e.printStackTrace();
                    // Toast.makeText(UploadImageDemo.this, "Exception : " +
                    // e.getMessage(), Toast.LENGTH_SHORT).show();
                    Log.e("Upload file to server Exception",
                            "Exception : " + e.getMessage(), e);
                }

            }
        };
        thread.start();

        try {
            thread.join();      
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        Debug.out("Message: " + serverResponseMessage.toString());
        return serverResponseCode;
    }
}

Answer 1

根据您的评论:“@Tarsem 我想在上传图片时显示进度对话框。所以当 ImageUploader 中的线程处于 Activity 状态时。”

尝试以下方法:

class imageupload extends AsyncTask<Void, Void, Void> {    
            Dialog dialog;    
            @Override
            protected void onPreExecute() {
                super.onPreExecute();
                dialog = ProgressDialog.show(context, "Uploading Image","Please Wait...");
            }    
            @Override
            protected Void doInBackground(Void... params) {
                // Upload Image HERE                    
                return null;
            }
            @Override
            protected void onPostExecute(Void result) {
                super.onPostExecute(result);
                dialog.dismiss();                   
                // You can Call another AsynTask here (achieve sending email work here)             
             }
        }