Android加载大图片OOM异常解决

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我是靠谱客的博主儒雅金针菇，最近开发中收集的这篇文章主要介绍Android加载大图片OOM异常解决，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

项目用到加载大图片，app老是出现OOM异常，总结了几点经验，供参考。

1、手动干涉dalvik的堆内存处理效率：

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private final static float TARGET_HEAP_UTILIZATION = 0.75f;
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//for same activity
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public void onCreate()
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{
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…………
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VMRuntime.getRuntime().setTargetHeapUtilization(TARGET_HEAP_UTILIZATION);
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…………
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}

2、手动指定Android堆大小：

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private final static int CWJ_HEAP_SIZE = 6* 1024* 1024 ;
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//for same activity
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public void onCreate()
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{
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…………
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VMRuntime.getRuntime().setMinimumHeapSize(CWJ_HEAP_SIZE); //设置最小heap内存为6MB大小。当然对于内存吃紧来说还可以通过手动干涉GC去处理

7 
…………
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}

3、手动指定回收内存，指定gc：

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if(bitmap!=null && !bitmap.isRecycled())
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{
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bitmap.recycle();
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System.gc();
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}

4、图片必须进行缩放，不然多半会出OOM：

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/**
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* @param url
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*
图片的url
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* @param sc
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*
，显示的像素大小
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* @return 返回指定RUL的缩略图
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*
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* @author jevan 2012-7-3
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*
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*/
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public static Bitmap loadImageFromUrl(String url, int sc)
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{
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URL m;
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InputStream i = null;
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BufferedInputStream bis = null;
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ByteArrayOutputStream out = null;
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if (url == null)
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return null;
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try
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{
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m = new URL(url);
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i = (InputStream) m.getContent();
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bis = new BufferedInputStream(i, 1024 * 4);
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out = new ByteArrayOutputStream();
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int len = 0;
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while ((len = bis.read(isBuffer)) != -1)
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{
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out.write(isBuffer, 0, len);
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}
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out.close();
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bis.close();
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} catch (MalformedURLException e1)
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{
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e1.printStackTrace();
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return null;
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} catch (IOException e)
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{
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e.printStackTrace();
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}
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if (out == null)
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return null;
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byte[] data = out.toByteArray();
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BitmapFactory.Options options = new BitmapFactory.Options();
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options.inJustDecodeBounds = true;
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BitmapFactory.decodeByteArray(data, 0, data.length, options);
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options.inJustDecodeBounds = false;
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int be = (int) (options.outHeight / (float) sc);
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if (be <= 0)
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{
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be = 1;
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} else if (be > 3)
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{
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be = 3;
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}
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options.inSampleSize = be;
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Bitmap bmp =null;
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try
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{
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bmp = BitmapFactory.decodeByteArray(data, 0, data.length, options); //返回缩略图
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} catch (OutOfMemoryError e)
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{
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// TODO: handle exception
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MainActivity.print("Tile Loader (241) Out Of Memory Error " + e.getLocalizedMessage());
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System.gc();
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bmp =null;
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}
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return bmp;
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}

把上面几条全部用上，OOM的异常基本上能完全避免！！！

以下内容为转载，收藏。

 1
//我们在BitmapManager.instance().decodeFile对图片进行解码，生成Bitmap的时候，我们会发现很多大图片会报OutOfMemoryError的错误，这个时候我们需要改变options里面的一些参数来解决这个问题，不然我们程序就跑不下去了。最简单的方法就是改变options.inSampleSize这个参数，把它增大，就可以解决很多图片OutOfMemoryError的问题。
 2
//下面是一个使用了这个方式的代码
 3
public static Bitmap makeBitmap(String path, int minSideLength, int maxNumOfPixels, BitmapFactory.Options options)
 4 
{
 5
Bitmap b = null;
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Log.i(TAG, "makeBitmap : path = " + path);
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if (path == null)
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return null;
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File f = new File(path);
10
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//try {
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// b = BitmapManager.instance().decodeFile(f, null);
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//} catch (OutOfMemoryError ex) {
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// Log.e(TAG, "Got oom exception, we may try one more time, using Options:" + ex.getMessage());
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if (options == null)
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{
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options = new BitmapFactory.Options();
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}
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try
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{
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options.inJustDecodeBounds = true;
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BitmapManager.instance().decodeFile(f, options);
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if (options.mCancel || options.outWidth == -1 || options.outHeight == -1)
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{
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return null;
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}
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options.inSampleSize = computeSampleSize(options, minSideLength, maxNumOfPixels);
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options.inJustDecodeBounds = false;
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options.inDither = true;
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options.inPreferredConfig = null;//Bitmap.Config.ARGB_8888;
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b = BitmapManager.instance().decodeFile(f, options);
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} catch (OutOfMemoryError ex2)
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{
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Log.e(TAG, "Got oom exception when retry the 2nd time,options.inSampleSize= " + options.inSampleSize + " minSideLength = "
37
+ minSideLength + " maxNumOfPixels =" + maxNumOfPixels, ex2);
38
try
39 
{
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options.inSampleSize += 1;
41
options.inJustDecodeBounds = false;
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options.inDither = true;
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options.inPreferredConfig = null;
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b = BitmapManager.instance().decodeFile(f, options);
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} catch (OutOfMemoryError e)
46 
{
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Log.e(TAG, "Got oom exception when retry the 2nd time,options.inSampleSize= " + options.inSampleSize + " minSideLength = "
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+ minSideLength + " maxNumOfPixels =" + maxNumOfPixels, e);
49
try
50 
{
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options.inSampleSize += 1;
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options.inJustDecodeBounds = false;
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options.inDither = true;
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options.inPreferredConfig = null;
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b = BitmapManager.instance().decodeFile(f, options);
56
} catch (OutOfMemoryError ex)
57 
{
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Log.e(TAG, "Got oom exception when retry the 2nd time,options.inSampleSize= " + options.inSampleSize
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+ " minSideLength = " + minSideLength + " maxNumOfPixels =" + maxNumOfPixels, ex);
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return null;
61 
}
62 
}
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}
64
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//} 
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return b;
67
}

 1
//另外一处代码
 2
public static Bitmap getBitpMap(InputStream is)
 3 
{
 4 
ParcelFileDescriptor pfd;
 5
try
 6 
{
 7
pfd = getContentResolver().openFileDescriptor(uri, "r");
 8
} catch (IOException ex)
 9 
{
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return null;
11 
}
12
java.io.FileDescriptor fd = pfd.getFileDescriptor();
13
BitmapFactory.Options options = new BitmapFactory.Options();
14
//先指定原始大小

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options.inSampleSize = 1;
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//只进行大小判断

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options.inJustDecodeBounds = true;
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//调用此方法得到options得到图片的大小

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BitmapFactory.decodeFileDescriptor(fd, null, options);
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//BitmapFactory.decodeStream(is, null, options);
21
//我们的目标是在800pixel的画面上显示。
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//所以需要调用computeSampleSize得到图片缩放的比例

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options.inSampleSize = computeSampleSize(options, 800);
24
//OK,我们得到了缩放的比例，现在开始正式读入BitMap数据

25
options.inJustDecodeBounds = false;
26
options.inDither = false;
27
options.inPreferredConfig = Bitmap.Config.ARGB_8888;
28
29
//根据options参数，减少所需要的内存
30
//
Bitmap sourceBitmap = BitmapFactory.decodeFileDescriptor(fd, null, options);
31
Bitmap sourceBitmap = BitmapFactory.decodeStream(is, null, options);
32
return sourceBitmap;
33 
}
34
35
//这个函数会对图片的大小进行判断，并得到合适的缩放比例，比如2即1/2,3即1/3

36
static int computeSampleSize(BitmapFactory.Options options, int target)
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{
38
int w = options.outWidth;
39
int h = options.outHeight;
40
int candidateW = w / target;
41
int candidateH = h / target;
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int candidate = Math.max(candidateW, candidateH);
43
if (candidate == 0)
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return 1;
45
if (candidate > 1)
46 
{
47
if ((w > target) && (w / candidate) < target)
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candidate -= 1;
49 
}
50
if (candidate > 1)
51 
{
52
if ((h > target) && (h / candidate) < target)
53
candidate -= 1;
54 
}
55
//if (VERBOSE)
56
Log.v(TAG, "for w/h " + w + "/" + h + " returning " + candidate + "(" + (w / candidate) + " / " + (h / candidate));
57
return candidate;
58
}