android - onCreate() で AsyncTask が実行されない

Question

私のアプリが初めて起動した場合、ウェブから画像をダウンロードしてその画像をに保存しDevice/Emulator、そこからDevice/Emulatorに表示する必要がありますImageView。私はこの方法で試しました：

ImageView myImgView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);     

    myImgView = (ImageView) findViewById(R.id.imageView1);      

    new MyAsnyc();
     Log.d(MY_TAGT, "AsyncTask Executed.....");

}
private class MyAsnyc extends AsyncTask<Void, Void,Void>{
    public File file ;
    InputStream is;
    private Bitmap bitmap;
    protected void doInBackground() throws IOException{

        File path = Environment.getExternalStoragePublicDirectory(
                Environment.DIRECTORY_PICTURES);
        file = new File(path, "DemoPicture.jpg");
        try{
            // Make sure the Pictures directory exists.
            path.mkdirs();

            URL url = new      URL(BASE_URL);
            /* Open a connection to that URL. */
            URLConnection ucon = url.openConnection();

            /*
             * Define InputStreams to read from the URLConnection.
             */
            is = ucon.getInputStream();

            OutputStream os = new FileOutputStream(file);
            byte[] data = new byte[is.available()];
            is.read(data);
            Log.i(MY_TAGT, "Picture is readable........");
            os.write(data);
            Log.i(MY_TAGT, "Picture is Saved........");
            is.close();
            os.close();

        }
        catch (IOException e) {
            Log.d("ImageManager", "Error: " + e);
        }
    }
    @Override
    protected Void doInBackground(Void... params) {
        // TODO Auto-generated method stub

        try {
            doInBackground();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return null;
    }
    protected void onPostExecute(){

        try{
            // Tell the media scanner about the new file so that it is
            // immediately available to the user.

            MediaScannerConnection.scanFile(null,
                    new String[] { file.toString() }, null,
                    new MediaScannerConnection.OnScanCompletedListener() {
                public void onScanCompleted(String path, Uri uri) {
                    Log.i("ExternalStorage", "Scanned " + path + ":");
                    Log.i("ExternalStorage", "-> uri=" + uri);
                }
            });
        }
        catch (Exception e) {
            // TODO: handle exception

        }

        /*Here I want to set this image in ImageView*/

        bitmap = BitmapFactory.decodeFile(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).toString()+"/DemoPicture.jpg");
        myImgView.setImageBitmap(bitmap);
    }
}

しかし、この方法でMyAsyncはクラスは実行されません。その方法を教えてください。

EDITこれは私のログです

ここに画像の説明を入力

score 6 · Accepted Answer

6

execute を使用して呼び出します。

new MyAsnyc().execute();

于 2013-03-07T12:29:05.553 に答える

score 1 · Accepted Answer

使用する

new MyAsnyc().execute();

それ以外の

new MyAsnyc();

AsyncTask.execute （Params ... params）メソッドがAsyncTaskの実行に使用されるため

編集：

次のようにファイルにデータを書き込むには、Whileまたはforループを使用します。

OutputStream os = new FileOutputStream(file);
            byte[] data = new byte[is.available()];

            Log.i(MY_TAGT, "Picture is readable........");
            int count;
            while ( (count = is.read(data)) >= 0 ) {
              os.write(data,0,count)
             }

            Log.i(MY_TAGT, "Picture is Saved........");
            is.close();
            os.close();

score 0 · Accepted Answer

0

AsyncTaskを実行するのを忘れました：

(new MyAsnyc()).execute();

于 2013-03-07T12:30:31.373 に答える

score 0 · Accepted Answer

行の前 Log.d(MY_TAGT, "AsyncTask Executed....."); 新しい AsyncTask オブジェクトを作成しただけで、execute() メソッドで実行を呼び出さなかった..

EDIT：2番目の問題は、実際にそのImageViewに表示したい画像がそれほど明確ではないことです..原因ビットマップ= BitmapFactory.decodeFile（..blahblahblah ..）はおそらくこの後nullになります..私にはあなたが与えているようですフォルダー名とその「ファイル」をビットマップにデコードしたかった..このデコードとビットマップ値に関するログをいくつか作成して、私たちに見せてください..

編集2:

ファイルパス = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES); ファイル file = new File(パス, "DemoPicture.jpg"); ビットマップ = BitmapFactory.decodeFile(ファイル);

もう少しうまくいくはずです..

score 0 · Accepted Answer

これを試す必要があります：

public class DownloadImage {    
public static File getImage(String imageUrl, String fileName){
File file = null;
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(imageUrl);
    Log.d("INFORMATION..", "FILE FOUNDED....");
    //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();
    Log.d("INFORMATION..", "FILE CONECTED....");
    //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 = Environment.getExternalStorageDirectory();
    //create a new file, specifying the path, and the filename
    //which we want to save the file as.
    file = new File(SDCardRoot, fileName);

    //this will be used to write the downloaded data into the file we created
    FileOutputStream fileOutput = new FileOutputStream(file);
    Log.d("INFORMATION..", "WRINTING TO FILE DOWNLOADED...." + file);
    //this will be used in reading the data from the internet
    InputStream inputStream = urlConnection.getInputStream();

    //this is the total size of the file
    int 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;
        Log.d("INFORMATION..", "FILE DOWNLOADED....");
        //this is where you would do something to report the prgress, like this maybe
        //updateProgress(downloadedSize, totalSize);

    }
    //close the output stream when done
    fileOutput.close();
    Log.d("INFORMATION..", "FILE DOWNLOADING COMPLETED....");
    //catch some possible errors...
} catch (MalformedURLException e) {
    e.printStackTrace();
} catch (IOException e) {
    e.printStackTrace();
}
return file;


 }
}

DownloadImage.getImage(String imageUrl, String fileName)これを次のMainActivity.javaように呼び出します。

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

ImageView imageView = (ImageView) findViewById(R.id.imageView1);

String url = "http://4.bp.blogspot.com/-8v_k_fOcfP8/UQIL4ufghBI/AAAAAAAAEDo/9ffRRTM9AnA/s1600/android-robog-alone.png"; 

String file = DownloadImage.getImage(url, "My Image.jpg").toString();

// Get file path on device and set it to imageView
Bitmap bitmap = BitmapFactory.decodeFile(file);
imageView.setImageBitmap(bitmap);
}
}

私はこれがあなたが探しているものだと思います！これがあなたを助けることを願っています

android - onCreate() で AsyncTask が実行されない

5 に答える 5

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