从缓存获取图像时虚拟机内存不足

Question

已知我正在解决的问题出现在具有 16 MB 堆内存的设备中，我需要解决它。我有线程从服务器获取图像（大图像）并将它们缓存然后显示。问题是我的内存不足。为了进一步解释一下，我发布了我的日志猫以及一些代码：

public class Test extends Activity implements OnClickListener {
ImageView paint, wheels, shadow;

Button b;
int j = 2;
int i = 1;
String pathToWheels, pathToPaint, pathToShadow;
String stringAngle;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    MemoryInfo dbm = new MemoryInfo();
    Debug.getMemoryInfo(dbm);
    b = (Button) findViewById(R.id.button1);
    b.setOnClickListener(this);



    wheels = (ImageView) findViewById(R.id.imageView3);
    paint = (ImageView) findViewById(R.id.imageView2);
    shadow = (ImageView) findViewById(R.id.imageView1);



    while (i < 13) {

        stringAngle = Integer.toString(i);
        String pathToWheels = url;
        String pathToPaint = url;
        String pathToShadow = url;

        if (Cache.getCacheFile(pathToWheels) == null) {
            ImageDownloader downloader1 = new ImageDownloader(wheels);
            downloader1
                    .execute(url);
        } else if (Cache.getCacheFile(pathToShadow) == null) {
            ImageDownloader downloader2 = new ImageDownloader(shadow);
            downloader2
                    .execute(url);


        } else if (Cache.getCacheFile(pathToPaint) == null) {

            ImageDownloader downloader = new ImageDownloader(paint);
            downloader
                    .execute(url);


        }

        i++;


    }

}



@Override
protected void onPause() {
    super.onPause();
    Toast.makeText(getApplicationContext(),"Pause",
            Toast.LENGTH_SHORT).show();

}

@Override
public void onClick(View v) {


    if (v.getId() == R.id.button1) {
        if (j == 13) 
        {
            j = 1;  
        }
        String s = Integer.toString(j);
        wheels.setImageBitmap(Cache
                .getCacheFile(url));
        paint.setImageBitmap(Cache
                .getCacheFile(url));
    shadow.setImageBitmap(Cache
                .getCacheFile(url));
        j++;



    }
}

}

从我的缓存类：

public static void saveCacheFile(String cacheUri, Bitmap image) {
    if(!isCacheWritable()) return;
    Log.i("CACHE S",cacheUri);
    cache.saveCacheFile(cacheUri, image);

从我的 CacheStore 类：

public Bitmap getCacheFile(String cacheUri) {
    if(bitmapMap.containsKey(cacheUri)) return (Bitmap)bitmapMap.get(cacheUri);

    if(!cacheMap.containsKey(cacheUri)) return null;
    String fileLocalName = cacheMap.get(cacheUri);
    File fullCacheDir = new     File(Environment.getExternalStorageDirectory().toString(),cacheDir);
    File fileUri = new File(fullCacheDir.toString(), fileLocalName);
    if(!fileUri.exists()) return null;
    Log.i("CACHE", "File "+cacheUri+" has been found in the Cache");
    Bitmap bm = BitmapFactory.decodeFile(fileUri.toString());
    Bitmap.createScaledBitmap(bm, 480, 320, true);
    bitmapMap.put(cacheUri, bm);
    return bm;
}

应用程序在这一行崩溃： Bitmap bm = BitmapFactory.decodeFile(fileUri.toString()); 我的内存不足了。

我的 logcat：

    07-06 23:40:20.720: ERROR/dalvikvm-heap(1844): 691200-byte external allocation too large for this process.
07-06 23:40:20.720: ERROR/GraphicsJNI(1844): VM won't let us allocate 691200 bytes
07-06 23:40:20.770: DEBUG/skia(1844): --- decoder->decode returned false
07-06 23:40:20.790: DEBUG/AndroidRuntime(1844): Shutting down VM
07-06 23:40:20.830: WARN/dalvikvm(1844): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
07-06 23:40:20.890: ERROR/AndroidRuntime(1844): FATAL EXCEPTION: main
07-06 23:40:20.890: ERROR/AndroidRuntime(1844): java.lang.OutOfMemoryError: bitmap size exceeds VM budget
07-06 23:40:20.890: ERROR/AndroidRuntime(1844):     at android.graphics.BitmapFactory.nativeDecodeStream(Native Method)
07-06 23:40:20.890: ERROR/AndroidRuntime(1844):     at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:459)
07-06 23:40:20.890: ERROR/AndroidRuntime(1844):     at android.graphics.BitmapFactory.decodeFile(BitmapFactory.java:271)
07-06 23:40:20.890: ERROR/AndroidRuntime(1844):     at android.graphics.BitmapFactory.decodeFile(BitmapFactory.java:296)
07-06 23:40:20.890: ERROR/AndroidRuntime(1844):     at com.cache.CacheStore.getCacheFile(CacheStore.java:117)
07-06 23:40:20.890: ERROR/AndroidRuntime(1844):     at com.cache.Cache.getCacheFile(Cache.java:38)
07-06 23:40:20.890: ERROR/AndroidRuntime(1844):     at com.cache.Test.onClick(Test.java:118)
07-06 23:40:20.890: ERROR/AndroidRuntime(1844):     at android.view.View.performClick(View.java:2408)
07-06 23:40:20.890: ERROR/AndroidRuntime(1844):     at android.view.View$PerformClick.run(View.java:8816)
07-06 23:40:20.890: ERROR/AndroidRuntime(1844):     at android.os.Handler.handleCallback(Handler.java:587)
07-06 23:40:20.890: ERROR/AndroidRuntime(1844):     at android.os.Handler.dispatchMessage(Handler.java:92)
07-06 23:40:20.890: ERROR/AndroidRuntime(1844):     at android.os.Looper.loop(Looper.java:123)
07-06 23:40:20.890: ERROR/AndroidRuntime(1844):     at android.app.ActivityThread.main(ActivityThread.java:4627)
07-06 23:40:20.890: ERROR/AndroidRuntime(1844):     at java.lang.reflect.Method.invokeNative(Native Method)
07-06 23:40:20.890: ERROR/AndroidRuntime(1844):     at java.lang.reflect.Method.invoke(Method.java:521)
07-06 23:40:20.890: ERROR/AndroidRuntime(1844):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
07-06 23:40:20.890: ERROR/AndroidRuntime(1844):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
07-06 23:40:20.890: ERROR/AndroidRuntime(1844):     at dalvik.system.NativeStart.main(Native Method)

任何帮助将不胜感激，感谢您的阅读。

Answer 1

您需要在将位图插入图像下载器内的缓存之前重新采样并缩放位图。

过去，我必须在从网络下载图像之前检测图像的文件大小。如果它太大我就使用默认图像。

此外，我还通过调整 BitmapFactory 采样大小来降低保存图像的分辨率，并调整应用程序中最终图像的大小。 （这为缓存节省了大量空间）。

请参阅如何了解文件的大小下载它？

//somewhere inside image downloader class...
{...}

BitmapFactory.Options options = new BitmapFactory.Options();

if(enableSampling)
    options.inSampleSize = 2;

returnBitmap = BitmapFactory.decodeStream(is, null, options);   

if(returnBitmap != null)
{

    if(scaleImage)
        returnBitmap = Bitmap.createScaledBitmap(returnBitmap, width, height, true);

    // insert the image into the cache
    imageCache.put(url, new SoftReference<Bitmap>(returnBitmap));


    // Check the ImageView for nulls
    if(imageView != null && callback != null){
        ImageDisplayer displayer = new ImageDisplayer(imageView, returnBitmap, parentView, tag);
        callback.onImageReceived(displayer);
    }

}

{...}

到目前为止，这对我来说很有效，并且对疯狂文件大小的检查使应用程序免于多次崩溃，更不用说它可以跳过在后台下载大量文件。

Answer 2

查看 BitmapFactory OOM 让我抓狂