Android OutOfMemoryError：加载图像时位图大小超过VM预算

Android OutOfMemoryError: bitmap size exceeds VM budget while loading images

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Possible Duplicate:
Android: Strange out of memory issue while loading an image to a Bitmap object

我正在使用一个Image Loader，它从URL加载图像并缓存到我的文件系统中。我发现使用ACRA的手机很少有以下崩溃报告

错误：

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java.lang.OutOfMemoryError: bitmap size exceeds VM budget
at android.graphics.BitmapFactory.nativeDecodeStream(Native Method)
at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:493)
at com.m7.nomad.utils.ImageLoader.decodeFile(ImageLoader.java:117)
at com.m7.nomad.utils.ImageLoader.getBitmap(ImageLoader.java:88)
at com.m7.nomad.utils.ImageLoader.access$0(ImageLoader.java:68)
at com.m7.nomad.utils.ImageLoader$PhotosLoader.run(ImageLoader.java:170)

ImageLoader.java

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package com.m7.nomad.utils;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Collections;
import java.util.Map;
import java.util.Stack;
import java.util.WeakHashMap;

import com.m7.nomad.R;

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.widget.ImageView;

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 thread low priority because it will not affect
// the
// UI performance
photoLoaderThread.setPriority(Thread.NORM_PRIORITY - 1);

fileCache = new FileCache(context);
}

final int stub_id = R.drawable.image_place_holder;

public void DisplayImage(String url, Activity activity, ImageView imageView) {
imageViews.put(imageView, url);
Bitmap bitmap = memoryCache.get(url);
if (bitmap != null)
imageView.setImageBitmap(bitmap);
else {
queuePhoto(url, activity, imageView);
imageView.setImageResource(stub_id);
}
}

private void queuePhoto(String url, Activity activity, 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();
}

private 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;
}
}

// decodes image and scales it to reduce memory consumption
private Bitmap decodeFile(File f) {
try {
// decode image size
BitmapFactory.Options o = new BitmapFactory.Options();
o.inJustDecodeBounds = true;
BitmapFactory.decodeStream(new FileInputStream(f), null, o);

// Find the correct scale value. It should be the power of 2.
final int REQUIRED_SIZE = 65;
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;
return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
} catch (FileNotFoundException e) {
}
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.setImageBitmap(bitmap);
else
imageView.setImageResource(stub_id);
}
}

public void clearCache() {
memoryCache.clear();
fileCache.clear();
}

}

这就是我调用ImageLoader的方式

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ImageView image = new ImageView(getActivity());

ImageLoader imgLoader = new ImageLoader(MainActivity.context);
imgLoader.DisplayImage(imagePath, new Activity(), image);