我试图在应用程序中显示大型位图，我继续获得OOM异常，
这是我使用的Imageloader类
public class ImageLoader {
MemoryCache memoryCache=new MemoryCache();
FileCache fileCache;
private Map<ImageView, String> imageViews=Collections.synchronizedMap(new WeakHashMap<ImageView, String>());
public ImageLoader(Context context){
//Make the background thead low priority. This way it will not affect the UI performance
photoLoaderThread.setPriority(Thread.NORM_PRIORITY-1);
fileCache=new FileCache(context);
}
// final int stub_id=R.drawable.stub;
public void DisplayImage(String url,ImageView imageView)
{
imageViews.put(imageView, url);
// Bitmap bitmap=createScaledBitmap(memoryCache.get(url), 100,100,0);
Bitmap bitmap=memoryCache.get(url);
// Bitmap bitmaps=bitmap.createScaledBitmap(bitmap, 0, 100, 100);
if(bitmap!=null)
{
imageView.setBackgroundDrawable(new BitmapDrawable(bitmap));
System.gc();
// bitmap.recycle();
// bitmap=null;
// imageView.setImageBitmap(getRoundedCornerBitmap( bitmap, 10,70,70));
// imageView.setImageBitmap(bitmap);
// Log.v("first", "first");
}
else
{
queuePhoto(url, imageView);
// Log.v("second", "second");
}
}
private Bitmap createScaledBitmap(Bitmap bitmap, int i, int j, int k) {
// TODO Auto-generated method stub
return null;
}
private void queuePhoto(String url, ImageView imageView)
{
//This ImageView may be used for other images before. So there may be some old tasks in the queue. We need to discard them.
photosQueue.Clean(imageView);
PhotoToLoad p=new PhotoToLoad(url, imageView);
synchronized(photosQueue.photosToLoad){
photosQueue.photosToLoad.push(p);
photosQueue.photosToLoad.notifyAll();
}
//start thread if it's not started yet
if(photoLoaderThread.getState()==Thread.State.NEW)
photoLoaderThread.start();
}
public Bitmap getBitmap(String url)
{
File f=fileCache.getFile(url);
//from SD cache
Bitmap b = decodeFile(f);
if(b!=null)
return b;
//from web
try {
Bitmap bitmap=null;
URL imageUrl = new URL(url);
HttpURLConnection conn = (HttpURLConnection)imageUrl.openConnection();
conn.setConnectTimeout(30000);
conn.setReadTimeout(30000);
InputStream is=conn.getInputStream();
OutputStream os = new FileOutputStream(f);
Utils.CopyStream(is, os);
os.close();
bitmap = decodeFile(f);
return bitmap;
} catch (Exception ex){
ex.printStackTrace();
return null;
}
}//Lalit
private Bitmap decodeFile(File f){
try {
//decode image size
BitmapFactory.Options o = new BitmapFactory.Options();
o.inJustDecodeBounds = true;
FileInputStream stream1=new FileInputStream(f);
BitmapFactory.decodeStream(stream1,null,o);
stream1.close();
//Find the correct scale value. It should be the power of 2.
final int REQUIRED_SIZE=Wall.width;
final int REQUIRED_SIZE1=Wall.height;
int width_tmp=o.outWidth, height_tmp=o.outHeight;
int scale=1;
while(true){
if(width_tmp/2<REQUIRED_SIZE || height_tmp/2<REQUIRED_SIZE)
break;
width_tmp/=2;
height_tmp/=2;
scale*=2;
}
//decode with inSampleSize
BitmapFactory.Options o2 = new BitmapFactory.Options();
o2.inSampleSize=scale;
FileInputStream stream2=new FileInputStream(f);
Bitmap bitmap=BitmapFactory.decodeStream(stream2, null, o2);
stream2.close();
return bitmap;
} catch (FileNotFoundException e) {
}
catch (IOException e) {
e.printStackTrace();
}
return null;
}
//Task for the queue
private class PhotoToLoad
{
public String url;
public ImageView imageView;
public PhotoToLoad(String u, ImageView i){
url=u;
imageView=i;
}
}
PhotosQueue photosQueue=new PhotosQueue();
public void stopThread()
{
photoLoaderThread.interrupt();
}
//stores list of photos to download
class PhotosQueue
{
private Stack<PhotoToLoad> photosToLoad=new Stack<PhotoToLoad>();
//removes all instances of this ImageView
public void Clean(ImageView image)
{
for(int j=0 ;j<photosToLoad.size();){
if(photosToLoad.get(j).imageView==image)
photosToLoad.remove(j);
else
++j;
}
}
}
class PhotosLoader extends Thread {
public void run() {
try {
while(true)
{
//thread waits until there are any images to load in the queue
if(photosQueue.photosToLoad.size()==0)
synchronized(photosQueue.photosToLoad){
photosQueue.photosToLoad.wait();
}
if(photosQueue.photosToLoad.size()!=0)
{
PhotoToLoad photoToLoad;
synchronized(photosQueue.photosToLoad){
photoToLoad=photosQueue.photosToLoad.pop();
}
Bitmap bmp=getBitmap(photoToLoad.url);
memoryCache.put(photoToLoad.url, bmp);
String tag=imageViews.get(photoToLoad.imageView);
if(tag!=null && tag.equals(photoToLoad.url)){
BitmapDisplayer bd=new BitmapDisplayer(bmp, photoToLoad.imageView);
Activity a=(Activity)photoToLoad.imageView.getContext();
a.runOnUiThread(bd);
}
}
if(Thread.interrupted())
break;
}
} catch (InterruptedException e) {
//allow thread to exit
}
}
}
PhotosLoader photoLoaderThread=new PhotosLoader();
//Used to display bitmap in the UI thread
class BitmapDisplayer implements Runnable
{
Bitmap bitmap;
ImageView imageView;
public BitmapDisplayer(Bitmap b, ImageView i){bitmap=b;imageView=i;}
public void run()
{
if(bitmap!=null)
imageView.setBackgroundDrawable(new BitmapDrawable(bitmap));
}
}
public void clearCache() {
memoryCache.clear();
fileCache.clear();
}
public static Bitmap getRoundedCornerBitmap(Bitmap bitmap, int pixels,int width,int height) {
Bitmap output = Bitmap.createBitmap(width,height, Config.ARGB_8888);
Canvas canvas = new Canvas(output);
final int color = 0xff424242;
final Paint paint = new Paint();
final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
final RectF rectF = new RectF(rect);
final float roundPx = pixels;
paint.setAntiAlias(true);
canvas.drawARGB(0, 0, 0, 0);
paint.setColor(color);
canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
canvas.drawBitmap(bitmap, rect, rect, paint);
return output;
}
}
我的Memorycache类
public class MemoryCache {
private static final String TAG = "MemoryCache";
private Map<String, Bitmap> cache=Collections.synchronizedMap(
new LinkedHashMap<String, Bitmap>(10,1.5f,true));//Last argument true for LRU ordering
private long size=0;//current allocated size
private long limit=1000000;//max memory in bytes
public MemoryCache(){
//use 25% of available heap size
setLimit(Runtime.getRuntime().maxMemory()/4);
}
public void setLimit(long new_limit){
limit=new_limit;
Log.i(TAG, "MemoryCache will use up to "+limit/1024./1024.+"MB");
}
public Bitmap get(String id){
try{
if(!cache.containsKey(id))
return null;
//NullPointerException sometimes happen here http://code.google.com/p/osmdroid/issues/detail?id=78
return cache.get(id);
}catch(NullPointerException ex){
ex.printStackTrace();
return null;
}
}
public void put(String id, Bitmap bitmap){
try{
if(cache.containsKey(id))
size-=getSizeInBytes(cache.get(id));
cache.put(id, bitmap);
size+=getSizeInBytes(bitmap);
checkSize();
}catch(Throwable th){
th.printStackTrace();
}
}
private void checkSize() {
Log.i(TAG, "cache size="+size+" length="+cache.size());
if(size>limit){
Iterator<Entry<String, Bitmap>> iter=cache.entrySet().iterator();//least recently accessed item will be the first one iterated
while(iter.hasNext()){
Entry<String, Bitmap> entry=iter.next();
size-=getSizeInBytes(entry.getValue());
iter.remove();
if(size<=limit)
break;
}
Log.i(TAG, "Clean cache. New size "+cache.size());
}
}
public void clear() {
try{
//NullPointerException sometimes happen here http://code.google.com/p/osmdroid/issues/detail?id=78
cache.clear();
size=0;
}catch(NullPointerException ex){
ex.printStackTrace();
}
}
long getSizeInBytes(Bitmap bitmap) {
if(bitmap==null)
return 0;
return bitmap.getRowBytes() * bitmap.getHeight();
}
}
这是logcat输出------------＆gt;
01-09 12:40:38.940: E/dalvikvm-heap(18736): 1123536-byte external allocation too large for this process.
01-09 12:40:38.979: D/GraphicsJNI(18736): Waiting for heap walker to free more memory
01-09 12:40:38.979: D/dalvikvm(18736): GC_FOR_MALLOC freed <1K, 53% free 4297K/8967K, external 22504K/23758K, paused 29ms
01-09 12:40:38.979: D/GraphicsJNI(18736): Heap walker done, retry to allocate
01-09 12:40:39.002: I/MemoryCache(18736): cache size=5691144 length=7
01-09 12:40:39.112: D/dalvikvm(18736): GC_EXTERNAL_ALLOC freed 89K, 53% free 4272K/8967K, external 21905K/22856K, paused 42ms
01-09 12:40:39.127: E/dalvikvm-heap(18736): 2457600-byte external allocation too large for this process.
01-09 12:40:39.167: D/GraphicsJNI(18736): Waiting for heap walker to free more memory
01-09 12:40:39.167: D/dalvikvm(18736): GC_FOR_MALLOC freed <1K, 53% free 4272K/8967K, external 21905K/22856K, paused 28ms
01-09 12:40:39.167: D/GraphicsJNI(18736): Heap walker done, retry to allocate
01-09 12:40:39.206: D/dalvikvm(18736): GC_EXTERNAL_ALLOC freed 2K, 53% free 4270K/8967K, external 20808K/22856K, paused 38ms
01-09 12:40:39.252: I/MemoryCache(18736): cache size=8148744 length=8
01-09 12:40:39.323: D/dalvikvm(18736): GC_EXTERNAL_ALLOC freed 148K, 53% free 4253K/8967K, external 23218K/25256K, paused 42ms
01-09 12:40:39.331: E/dalvikvm-heap(18736): 960000-byte external allocation too large for this process.
01-09 12:40:39.370: D/GraphicsJNI(18736): Waiting for heap walker to free more memory
01-09 12:40:39.370: D/dalvikvm(18736): GC_FOR_MALLOC freed <1K, 53% free 4253K/8967K, external 23218K/25256K, paused 28ms
01-09 12:40:39.377: D/GraphicsJNI(18736): Heap walker done, retry to allocate
01-09 12:40:39.409: D/dalvikvm(18736): GC_EXTERNAL_ALLOC freed 1K, 53% free 4251K/8967K, external 23208K/25256K, paused 38ms
01-09 12:40:39.424: E/dalvikvm-heap(18736): 960000-byte external allocation too large for this process.
01-09 12:40:39.463: E/GraphicsJNI(18736): VM won't let us allocate 960000 bytes
01-09 12:40:39.463: D/dalvikvm(18736): GC_FOR_MALLOC freed 0K, 53% free 4251K/8967K, external 23208K/25256K, paused 28ms
01-09 12:40:39.463: D/skia(18736): --- decoder->decode returned false
01-09 12:40:39.463: W/dalvikvm(18736): threadid=16: thread exiting with uncaught exception (group=0x40018560)
01-09 12:40:39.471: E/AndroidRuntime(18736): FATAL EXCEPTION: Thread-26
01-09 12:40:39.471: E/AndroidRuntime(18736): java.lang.OutOfMemoryError: bitmap size exceeds VM budget
01-09 12:40:39.471: E/AndroidRuntime(18736): at android.graphics.BitmapFactory.nativeDecodeStream(Native Method)
01-09 12:40:39.471: E/AndroidRuntime(18736): at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:470)
01-09 12:40:39.471: E/AndroidRuntime(18736): at com.beerbro.utils.ImageLoader.decodeFile(ImageLoader.java:190)
01-09 12:40:39.471: E/AndroidRuntime(18736): at com.beerbro.utils.ImageLoader.getBitmap(ImageLoader.java:100)
01-09 12:40:39.471: E/AndroidRuntime(18736): at com.beerbro.utils.ImageLoader$PhotosLoader.run(ImageLoader.java:257)
01-09 12:40:39.471: W/ActivityManager(1320): Force finishing activity com.stellent.beerbro/.Wall
我正在从Facebook图形api加载数据，我正在获取Firstpage数据，我一次显示整个数据。我认为这会使内存增加很多。 那么，如何处理大量数据。 请帮忙
答案 0 :(得分：0)
您应该使用inJustDecodeBounds解码位图的大小而不将其加载到内存中。 ATM，如果您尝试加载大型位图，则在检查它是否在缓存的大小范围内之前创建它。
您不应强制使用GC，尤其是因为它是异步运行而system.gc强制它是同步的。位图不会直接加载到Java堆上，因此从缓存中传出的任何内容都应该被回收。最后不要保留对位图的引用。
总的来说，我会使用LRUCache而不是你自己的缓存。
最后，作为偏见，我会建议像enter link description here那样将图像缓存到磁盘并使用LRUCache进行表演。