位图占据了很多记忆

Question

我收到一个错误,说Bitmaps正在使用大量内存.

我知道我应该使用bitmap.recyle()但我不知道在哪里放它,无论我把它放在哪里我得到一个错误说我正在尝试使用循环位图.

如果有人能提供帮助,那就太棒了.

这是我的相关代码:

public class PictureViewer extends SherlockActivity implements
    android.view.GestureDetector.OnGestureListener {

private ViewFlipper viewFlipper = null;
private GestureDetector gestureDetector = null;
ArrayList<Integer> number = new ArrayList<Integer>();
DownloadBitmap bit = new DownloadBitmap();

int j = 1;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    // Remove title bar
    this.requestWindowFeature(Window.FEATURE_NO_TITLE);
    setContentView(R.layout.pictureviewer);
    viewFlipper = (ViewFlipper) findViewById(R.id.viewflipper);
    gestureDetector = new GestureDetector(this);

    for (int i = 1; i <= 65; ++i)
        number.add(i);
    Collections.shuffle(number);

    loadImage();
    loadImage();
}

public void loadImage() {

    if (j == 65) { // Change this number to exact ammount of pictures
        j = 1;
    }
    int next = number.get(j);
    j++;

    ImageView image = new ImageView(this);
    Bitmap bitmap = bit.createBitmapFromUrl("http://comedyzone.mobi/img" + next + ".jpg");
    WeakReference<Bitmap> mBitmapReference = new WeakReference<Bitmap>(bitmap);
    image.setImageBitmap(mBitmapReference.get());
    image.setScaleType(ImageView.ScaleType.FIT_XY);
    viewFlipper.addView(image, new LayoutParams(LayoutParams.FILL_PARENT,
            LayoutParams.FILL_PARENT));
}

@Override
public boolean onDown(MotionEvent arg0) {
    // TODO Auto-generated method stub
    return false;
}

@Override
public boolean onFling(MotionEvent arg0, MotionEvent arg1, float arg2,
        float arg3) {
    // TODO Auto-generated method stub
    if (arg0.getX() - arg1.getX() > 120) {

        this.viewFlipper.setInAnimation(AnimationUtils.loadAnimation(this,
                R.anim.push_left_in));
        this.viewFlipper.setOutAnimation(AnimationUtils.loadAnimation(this,
                R.anim.push_left_out));
        this.viewFlipper.showNext();
        loadImage();
        return true;
    } else if (arg0.getX() - arg1.getX() < -120) {
        this.viewFlipper.setInAnimation(AnimationUtils.loadAnimation(this,
                R.anim.push_right_in));
        this.viewFlipper.setOutAnimation(AnimationUtils.loadAnimation(this,
                R.anim.push_right_out));
        this.viewFlipper.showPrevious();
        loadImage();
        return true;
    }
    return true;
}

@Override
public void onLongPress(MotionEvent arg0) {
    // TODO Auto-generated method stub

}

@Override
public boolean onScroll(MotionEvent arg0, MotionEvent arg1, float arg2,
        float arg3) {
    // TODO Auto-generated method stub
    return false;
}

@Override
public void onShowPress(MotionEvent arg0) {
    // TODO Auto-generated method stub

}

@Override
public boolean onSingleTapUp(MotionEvent arg0) {
    // TODO Auto-generated method stub
    return false;
}

@Override
public boolean onTouchEvent(MotionEvent event) {
    return this.gestureDetector.onTouchEvent(event);
}

private InputStream OpenHttpConnection(String urlString) throws IOException {
    InputStream in = null;
    int response = -1;

    URL url = new URL(urlString);
    URLConnection conn = url.openConnection();

    if (!(conn instanceof HttpURLConnection))
        throw new IOException("Not an HTTP connection");

    try {
        HttpURLConnection httpConn = (HttpURLConnection) conn;
        httpConn.setAllowUserInteraction(false);
        httpConn.setInstanceFollowRedirects(true);
        httpConn.setRequestMethod("GET");
        httpConn.connect();

        response = httpConn.getResponseCode();
        if (response == HttpURLConnection.HTTP_OK) {
            in = httpConn.getInputStream();
        }
    } catch (Exception ex) {
        throw new IOException("Error connecting");
    }
    return in;
}

Answer 1

我知道我应该使用bitmap.recyle()

recycle不需要打电话.

去年在谷歌IO上,有一个关于这个主题的演讲.

Google I/O 2011:Android应用程序的内存管理 - 您一定要关注所有这些,值得花时间.

制作WeakReference你的Bitmap目标是争取更好的良好开局Bitmap管理.例如:

Bitmap bitmap = DownloadImage("http://comedyzone.mobi/img" + next + ".jpg");
WeakReference<Bitmap> mBitmapReference = new WeakReference<Bitmap>(bitmap);
image.setImageBitmap(mBitmapReference.get());

有效显示位图

这些是您应该阅读的Android培训课程.

此外,这是我写的一个从URL下载图像的类.您应该考虑使用它来代替您的DownloadImage方法,它会更有效率.

DownloadBitmap

public class DownloadBitmap {

private static String LOG_TAG = DownloadBitmap.class.getName();

/**
 * @param url
 * @return Bitmap image from the interwebs
 */
static Bitmap createBitmapFromUrl(String url) {
    final Bitmap mBitmap = readBitmapFromNetwork(url);
    final WeakReference<Bitmap> mBitmapReference = new WeakReference<Bitmap>(mBitmap);
    if (mBitmapReference.get() != null)
        return mBitmapReference.get();
    return null;
}

/**
 * @param urlString The URL to read the bitmap from.
 * @return A Bitmap image or null if an error occurs.
 */
private static Bitmap readBitmapFromNetwork(String urlString) {
    InputStream mInputStream = null;
    FlushedInputStream mFlushedInputStream = null;
    Bitmap mBitmap = null;
    WeakReference<Bitmap> mBitmapReference = null;
    try {
        final BitmapFactory.Options mOptions = new BitmapFactory.Options();
        mOptions.inPurgeable = true;
        mOptions.inDither = false;
        final URL mUrl = new URL(urlString);
        final URLConnection mConnection = mUrl.openConnection();
        mConnection.connect();
        mInputStream = mConnection.getInputStream();
        mFlushedInputStream = new FlushedInputStream(mInputStream);
        mBitmap = BitmapFactory.decodeStream(mFlushedInputStream, null, mOptions);
        mBitmapReference = new WeakReference<Bitmap>(mBitmap);
    } catch (MalformedURLException e) {
        if (BuildConfig.DEBUG)
            Log.e(LOG_TAG, "Bad image URL", e);
        return null;
    } catch (IOException e) {
        if (BuildConfig.DEBUG)
            Log.e(LOG_TAG, "Could not get remote image", e);
        return null;
    } finally {
        try {
            if (mInputStream != null)
                mInputStream.close();
            if (mFlushedInputStream != null)
                mFlushedInputStream.close();
        } catch (IOException e) {
            if (BuildConfig.DEBUG)
                Log.e(LOG_TAG, "Error closing stream.");
            return null;
        }
    }
    if (mBitmapReference.get() != null)
        return mBitmapReference.get();
    return null;
}

/**
 * An InputStream that skips the exact number of bytes provided, unless it
 * reaches EOF.
 */
static class FlushedInputStream extends FilterInputStream {
    public FlushedInputStream(InputStream inputStream) {
        super(inputStream);
    }

    @Override
    public long skip(long n) throws IOException {
        long totalBytesSkipped = 0L;
        while (totalBytesSkipped < n) {
            long bytesSkipped = in.skip(n - totalBytesSkipped);
            if (bytesSkipped == 0L) {
                int bytes = read();
                if (bytes < 0) {
                    break;
                } else {
                    bytesSkipped = 1;
                }
            }
            totalBytesSkipped += bytesSkipped;
        }
        return totalBytesSkipped;
    }
  }
}