developerWab
developerWab
2013-08-28 07:29
采纳率: 69.1%
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android-创建下载应用

使用Android代码创建一个下载应用,不知道怎么开始?请有经验的前辈给些指点,谢谢。

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2条回答 默认 最新

  • Jave_
    JaveZh 2013-08-28 07:35
    已采纳

    是要写下载还是说写一个下载类型的应用?

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  • loFataMer
    loFataMer 2013-08-28 08:54
    public class AndroidDownloadFileByProgressBarActivity extends Activity {
    
        // button to show progress dialog
        Button btnShowProgress
    
        // Progress Dialog
        private ProgressDialog pDialog;
    
        // Progress dialog type (0 - for Horizontal progress bar)
        public static final int progress_bar_type = 0;
    
        // File url to download
        private static String file_url = " u r l";
    
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);
    
            // show progress bar button
            btnShowProgress = (Button) findViewById(R.id.btnProgressBar);
            // Image view to show image after downloading
            my_image = (ImageView) findViewById(R.id.my_image);
    
            /**
             * Show Progress bar click event
             * */
            btnShowProgress.setOnClickListener(new View.OnClickListener() {
    
                @Override
                public void onClick(View v) {
                    // starting new Async Task
                    new DownloadFileFromURL().execute(file_url);
                }
            });
        }
    
    
    @Override
    protected Dialog onCreateDialog(int id) {
        switch (id) {
        case progress_bar_type:
            pDialog = new ProgressDialog(this);
            pDialog.setMessage("Downloading file. Please wait...");
            pDialog.setIndeterminate(false);
            pDialog.setMax(100);
            pDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
            pDialog.setCancelable(true);
            pDialog.show();
            return pDialog;
        default:
            return null;
        }
    }
    
    
    class DownloadFileFromURL extends AsyncTask<String, String, String> {
    
        /**
         * Before starting background thread
         * Show Progress Bar Dialog
         * */
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            showDialog(progress_bar_type);
        }
    
        /**
         * Downloading file in background thread
         * */
        @Override
        protected String doInBackground(String... f_url) {
            int count;
            try {
                URL url = new URL(f_url[0]);
                URLConnection conection = url.openConnection();
                conection.connect();
                // getting file length
                int lenghtOfFile = conection.getContentLength();
    
                // input stream to read file - with 8k buffer
                InputStream input = new BufferedInputStream(url.openStream(), 8192);
    
                // Output stream to write file
                OutputStream output = new FileOutputStream("/sdcard/downloadedfile.jpg");
    
                byte data[] = new byte[1024];
    
                long total = 0;
    
                while ((count = input.read(data)) != -1) {
                    total += count;
                    // publishing the progress....
                    // After this onProgressUpdate will be called
                    publishProgress(""+(int)((total*100)/lenghtOfFile));
    
                    // writing data to file
                    output.write(data, 0, count);
                }
    
                // flushing output
                output.flush();
    
                // closing streams
                output.close();
                input.close();
    
            } catch (Exception e) {
                Log.e("Error: ", e.getMessage());
            }
    
            return null;
        }
    
        /**
         * Updating progress bar
         * */
        protected void onProgressUpdate(String... progress) {
            // setting progress percentage
            pDialog.setProgress(Integer.parseInt(progress[0]));
       }
    
        /**
         * After completing background task
         * Dismiss the progress dialog
         * **/
        @Override
        protected void onPostExecute(String file_url) {
            // dismiss the dialog after the file was downloaded
            dismissDialog(progress_bar_type);
        }
    }
    

    修改url和location

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