从服务器下载文件时进度条卡在 0%？

Posted 2023-05-07

【中文标题】从服务器下载文件时进度条卡在 0%？

【英文标题】：ProgressBar get Stucked at 0% while downloading file from server?

【发布时间】：2016-12-24 22:23:53

【问题描述】：

我正在创建一个 android 应用程序来下载一个 mp3 文件 服务器。下载工作正常。但是ProgressBar 是 下载时卡在 0%...

MainActivity.java

public class MainActivity extends Activity 

    // button to show progress dialog
    Button btnShowProgress;

    // Progress Dialog
    private ProgressDialog pDialog;
    ImageView my_image;
    // 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 = "http://eecindia.co.in/up/01%20-%20Pretham%20-%20Oruthikku%20Pinnil%20[Maango.me].mp3";

    @Override
    public void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_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);
            
        );
    

    /**
     * Showing Dialog
     * */
    @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(false);
                pDialog.show();
                return pDialog;
            default:
                return null;
        
    

    /**
     * Background Async Task to download file
     * */
    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.mp3");

                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);

            // Displaying downloaded image into image view
            // Reading image path from sdcard
           // String imagePath = Environment.getExternalStorageDirectory().toString() + "/downloadedfile.mp3";
            // setting downloaded into image view
            Toast.makeText(MainActivity.this, "Downloaded Succesfully.. check SD card 2 see file...", Toast.LENGTH_SHORT).show();

            //my_image.setImageDrawable(Drawable.createFromPath(imagePath));
        

    

【问题讨论】：

您覆盖 onCreateDialog()。在哪个级别？。 showDialog() 属于哪个类？

在 onProgressUpdate() 方法中为进度 [0] 输入日志并检查即将到来的值（你得到的值不是零吗？）

【参考方案1】：

上述过程适用于图像文件，但对于大文件会卡住，然后您必须在 doinbackground 方法中更改此代码并查看..它有效:)

HttpURLConnection connection = (HttpURLConnection)url.openConnection(); connection.setRequestMethod("HEAD"); 
connection.connect(); 
int length = connection.getContentLength();