位图占据了很多记忆

时间：2012-07-13 04:15:52

标签： android bitmap

我收到一条错误，指出位图正在使用很多内存。

我知道我应该使用bitmap.recyle（）但是我不知道在哪里放它，无论我把它放在哪里我都会收到错误，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。

以下是我的相关代码：

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;
}

5 个答案:

答案 0 :(得分：6)

  

我知道我应该使用bitmap.recyle（）

无需拨打recycle。

去年在谷歌IO上，有一个关于这个主题的演讲。

Google I/O 2011: Memory management for Android Apps - 你一定要注意这一切，值得花时间。

为WeakReference对象制作Bitmap是改善Bitmap管理的良好开端。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

These are Android training classes you should read through too.

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DownloadImage方法，它会更有效率。

<强> 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;
    }
  }
}

答案 1 :(得分：1)

在使用之前，您需要减小位图的样本大小。这可以用来做到这一点。

 private Bitmap decodeFile(File file)
{
    try 
    {
        //********************* decode image size ********************
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeStream(new FileInputStream(file), null, options);

        // ********************** Find the correct scale value. It should be the power of 2. ********************
        options.inSampleSize = BitmapConverter.calculateInSampleSize(options, 145, 105);
        options.inJustDecodeBounds = false;

        return BitmapFactory.decodeStream(new FileInputStream(file), null, options);
    } 
    catch(FileNotFoundException eFileNotFoundException) 
    {

        return null;
    }
}

然后你可以根据需要调用Bitmap.recycle（），虽然我觉得没必要。

答案 2 :(得分：0)

ImageLoader
您可以使用Imageloader类在后台加载图像  Imageloader

答案 3 :(得分：0)

您可以在bitmap.recycle()函数之后的image.setImageBitmap(bitmap);语句之后写loadImage()，因为在此语句之后不再需要位图。

发生此错误是因为您使用的是非常大的位图，或者您的代码中存在内存泄漏。

无论何时使用位图，都要尽量使用所有可能的Options作为最小内存。

有关详细信息，请参阅我的answer同一问题。

答案 4 :(得分：0)

一般来说，在不再需要时，应标记要清理的对象。在你的情况下，我唯一一次看到你不再需要这些位图就是当活动不再在前面时。

我看到的是ViewFlipper可能会使用不必要的大位图。您应该在将位图设置在ImageView内部之前调整位图的大小，而不是在添加它们之后调整ImageView的大小。尝试使用inSampleSize作为BitmapFactory的选项，并在将位图加载到ImageView之前使用Bitmap.createScaledBitmap（）调整位图大小。

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