Progress Download Dialog

问题

How do you implement Progress Download Dialog based on the codes below? My codes downloads images from a specific URL then it saves the image file into SD Card and set the image as wallpaper. I want to show a Progress Download Dialog when the user touches the options menu button setwallpaper().

public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.set_wallpaper:
                SetWallpaper(image_url);
                return true;
            default:
                return false;
        }
    }



public void SetWallpaper(String image_url)
        {   
        URL myFileUrl = null;
            try
        {   
                myFileUrl = new URL(image_url); 
        }
            catch (MalformedURLException e)
            {      
                e.printStackTrace();  
            }   
            Bitmap bmImg = null;
            try {  
                HttpURLConnection conn = (HttpURLConnection) myFileUrl.openConnection();   
                conn.setDoInput(true);   
                conn.connect();     
                //int length = conn.getContentLength(); 
            InputStream is = conn.getInputStream();
            bmImg = BitmapFactory.decodeStream(is); 
            }
                catch (IOException e)
                {       
                    e.printStackTrace();  
                }   
        try {       

            String path = myFileUrl.getPath();
            String idStr = path.substring(path.lastIndexOf('/') + 1);
            File filepath = Environment.getExternalStorageDirectory();
            File dir = new File (filepath.getAbsolutePath() + "/Wallpaper/");
                dir.mkdirs();
                String fileName = idStr;
                File file = new File(dir, fileName);
                FileOutputStream fos = new FileOutputStream(file);

                bmImg.compress(CompressFormat.JPEG, 75, fos);   
                fos.flush();    
                fos.close();       

                WallpaperManager wpm = WallpaperManager.getInstance(getBaseContext());
                wpm.setBitmap(bmImg);

        }
        catch (Exception e){


            e.printStackTrace();  
        }
        }

My attempt : Caught Exception . Please refer below codes

    public class SingleMenuItemActivity  extends Activity {

    // XML node keys
static final String KEY_TITLE = "title";
static final String KEY_ARTIST = "artist";  
static final String KEY_THUMB_URL = "thumb_url";
ProgressBar progressbar;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.single_list_item);

        ImageView image = (ImageView) findViewById(R.id.single_image);
        Intent in = getIntent();

        String image_url = in.getStringExtra(KEY_THUMB_URL);


        ImageLoader imgLoader = new ImageLoader(getApplicationContext());


        imgLoader.DisplayImage(image_url, image);

        String title = in.getStringExtra(KEY_TITLE);
        String artist = in.getStringExtra(KEY_ARTIST);


        TextView lblName = (TextView) findViewById(R.id.name_title);
        TextView lblCost = (TextView) findViewById(R.id.name_artist);
        progressbar = (ProgressBar) findViewById(R.id.loadingBar);

        lblName.setText(title);
        lblCost.setText(artist);


    }

    public class loadImageTask extends AsyncTask<String, Void, Void>
    {
        //Drawable imgLoad;
        URL myFileUrl = null;
        Bitmap bmImg = null;
        @Override
        protected void onPreExecute() {
            // TODO Auto-generated method stub
            Intent in = getIntent();
        String image_url = in.getStringExtra(KEY_THUMB_URL);
        try {
            myFileUrl = new URL(image_url);
        } catch (MalformedURLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } 
        super.onPreExecute();

        progressbar.setVisibility(View.VISIBLE);
    }

        @Override
        protected Void doInBackground(String... params) {
            // TODO Auto-generated method stub

            try {  
                HttpURLConnection conn = (HttpURLConnection) myFileUrl.openConnection();   
                conn.setDoInput(true);   
                conn.connect();     
                InputStream is = conn.getInputStream();
                bmImg = BitmapFactory.decodeStream(is); 
            }
            catch (IOException e)
            {       
                e.printStackTrace();  
            }
            try {       

                String path = myFileUrl.getPath();
                String idStr = path.substring(path.lastIndexOf('/') + 1);
            File filepath = Environment.getExternalStorageDirectory();
            File dir = new File (filepath.getAbsolutePath() + "/Wallpaper/");
                dir.mkdirs();
                String fileName = idStr;
                File file = new File(dir, fileName);
                FileOutputStream fos = new FileOutputStream(file);
                bmImg.compress(CompressFormat.JPEG, 75, fos);   
                fos.flush();    
                fos.close();       
            }
            catch (Exception e)
                    {
                        e.printStackTrace();  
                    }
            return null;   
        }
        @Override
        protected void onPostExecute(Void result) {
            // TODO Auto-generated method stub
            super.onPostExecute(result);

            if(progressbar.isShown())
            {
                progressbar.setVisibility(View.GONE);

            }
        }
    }




    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main_menu, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        Intent in = getIntent();
        String image_url = in.getStringExtra(KEY_THUMB_URL);
        switch (item.getItemId()) {
            case R.id.save_image:
                new loadImageTask().execute(image_url);

                return true;
            default:
                return false;
        }

回答1:

Here you can use the AsyncTask for the show the progressbar/dialogbox .

Show the progress bar visible inside the onPreExecute() method. And performs the image loading operations inside the doInBackground() method. Once this operation is done, we will make progress bar invisible and make imageview visible with that loaded image inside the onPostExecute() method.

For more information check this LINK

回答2:

Try using this

final ProgressDialog dialog = ProgressDialog.show(
            YourACtivity.this, "", "Loading...please wait");

    new Thread(new Runnable() {
        @Override
        public void run() {
        SetWallpaper(image_url);
                  if (dialog != null && dialog.isShowing()) {
                        dialog.dismiss();
                    }
        }
    }).start();

}

instead of

SetWallpaper(image_url);

in the onOptionsItemSelected(MenuItem item)

and next use Handlers to handle http://developer.android.com/reference/android/os/Handler.html

来源：https://stackoverflow.com/questions/11999218/progress-download-dialog