【Android】使用AsyncTask下載檔案

簡單運用, 記得改一些參數



    private class downloadPost extends AsyncTask<String, Integer, String> {
        private Context context;
        private ProgressDialog pd;
        private String strUrl;

        public downloadPost(Context context, String url) {
            this.context = context;
            strUrl = url;
        }

        @Override
        protected void onPreExecute() {
            pd = new ProgressDialog(context);
            pd.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
            pd.setMessage("下載中 ...");
            pd.setCancelable(false);
            pd.show();


        }

        @Override
        protected String doInBackground(String... params) {


            downloadFile(strUrl);


            return null;
        }


        // run Progress
        @Override
        protected void onProgressUpdate(Integer... values) {

            super.onProgressUpdate(values);

            if (pv.DEBUG_MODE) System.out.println(TAG + "values:" + values[0]);

            pd.setProgress(values[0]); // update Progress

        }


        // cancel upload
        @Override
        protected void onCancelled() {

            if (pv.DEBUG_MODE) System.out.println(TAG + "onCancelled");

        }

        @Override
        protected void onPostExecute(String result) {
            if (pv.DEBUG_MODE) {
                System.out.println("result onPostExecute : " + result);
            }


            player = new MusicPlayer(saveFileName, skbProgress);

            pd.dismiss();

            Toast.makeText(LessonContentActivity.this, "下載完成", Toast.LENGTH_SHORT).show();
        }


        private void downloadFile(String fileUrl) {
            try {
                //set the download URL, a url that points to a file on the internet
                //this is the file to be downloaded
                URL url = new URL(fileUrl);

                //create the new connection
                HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();

                //set up some things on the connection
                urlConnection.setRequestMethod("GET");
                urlConnection.setDoOutput(true);

                //and connect!
                urlConnection.connect();
                //set the path where we want to save the file
                //in this case, going to save it on the root directory of the
                //sd card.
                File SDCardRoot = new File(Environment.getExternalStorageDirectory() + "/easylisten/" + courseId + "/");
                if (!SDCardRoot.exists()) {
                    SDCardRoot.mkdirs();
                }
                //create a new file, specifying the path, and the filename
                //which we want to save the file as.

                //file Name : i.am.a.file.jpg || hahaha
                //fileUrl : http://solvefzt2.fzt.cc/.../i.am.a.file.jpg || hahaha.png
                String realFileName = fileUrl.split("/")[fileUrl.split("/").length - 1];
                String fileMime = realFileName.split("\\.")[realFileName.split("\\.").length - 1];

                if (pv.DEBUG_MODE) {

                    System.out.println(TAG + "realFileName:" + realFileName);
                    System.out.println(TAG + "fileMime:" + fileMime);
                }

                File file = null;

                file = new File(SDCardRoot, realFileName);

                if (pv.DEBUG_MODE) {
                    System.out.println(TAG + "file.isFile SDCardRoot,realFileName:" + SDCardRoot + "/" + realFileName);
                }
                saveFileName = SDCardRoot + "/" + realFileName;

                if (file.isFile()) {

                    return;
                }

                //this will be used to write the downloaded data into the file we created
                FileOutputStream fileOutput = new FileOutputStream(file);

                //this will be used in reading the data from the internet
                InputStream inputStream = urlConnection.getInputStream();


                //this is the total size of the file
                totalSize = urlConnection.getContentLength();


                //variable to store total downloaded bytes
                int downloadedSize = 0;

                //create a buffer...
                byte[] buffer = new byte[1024];
                int bufferLength = 0; //used to store a temporary size of the buffer

                //now, read through the input buffer and write the contents to the file
                while ((bufferLength = inputStream.read(buffer)) > 0) {
                    //add the data in the buffer to the file in the file output stream (the file on the sd card
                    fileOutput.write(buffer, 0, bufferLength);
                    //add up the size so we know how much is downloaded
                    downloadedSize += bufferLength;

                    //this is where you would do something to report the Progress
                    publishProgress((int) ((downloadedSize / totalSize) * 100));

                    fileOutput.flush();
                }
                //close the output stream when done
                fileOutput.close();


                //catch some possible errors...
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

    }