【OOM】Android加载大图片OOM异常解决

1、手动干涉dalvik的堆内存处理效率：

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

2、手动指定Android堆大小：

private final static int CWJ_HEAP_SIZE = 6* 1024* 1024 ;      //for same activity     public void onCreate()     {         …………         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           …………     }

3、手动指定回收内存，指定gc：

1         if(bitmap!=null && !bitmap.isRecycled())2         {3             bitmap.recycle();4             System.gc();5         }

4、图片必须进行缩放，不然多半会出OOM：

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

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。

//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。     //下面是一个使用了这个方式的代码     public static Bitmap makeBitmap(String path, int minSideLength, int maxNumOfPixels, BitmapFactory.Options options)     {         Bitmap b = null;         Log.i(TAG, "makeBitmap : path = " + path);         if (path == null)             return null;         File f = new File(path);          //try {         // b = BitmapManager.instance().decodeFile(f, null);         //} catch (OutOfMemoryError ex) {         // Log.e(TAG, "Got oom exception, we may try one more time, using Options:" + ex.getMessage());         if (options == null)         {             options = new BitmapFactory.Options();         }          try         {             options.inJustDecodeBounds = true;             BitmapManager.instance().decodeFile(f, options);             if (options.mCancel || options.outWidth == -1 || options.outHeight == -1)             {                 return null;             }             options.inSampleSize = computeSampleSize(options, minSideLength, maxNumOfPixels);             options.inJustDecodeBounds = false;             options.inDither = true;             options.inPreferredConfig = null;//Bitmap.Config.ARGB_8888;              b = BitmapManager.instance().decodeFile(f, options);         } catch (OutOfMemoryError ex2)         {             Log.e(TAG, "Got oom exception when retry the 2nd time,options.inSampleSize= " + options.inSampleSize + " minSideLength = "                     + minSideLength + " maxNumOfPixels =" + maxNumOfPixels, ex2);             try             {                 options.inSampleSize += 1;                 options.inJustDecodeBounds = false;                 options.inDither = true;                 options.inPreferredConfig = null;                 b = BitmapManager.instance().decodeFile(f, options);             } catch (OutOfMemoryError e)             {                 Log.e(TAG, "Got oom exception when retry the 2nd time,options.inSampleSize= " + options.inSampleSize + " minSideLength = "                         + minSideLength + " maxNumOfPixels =" + maxNumOfPixels, e);                 try                 {                     options.inSampleSize += 1;                     options.inJustDecodeBounds = false;                     options.inDither = true;                     options.inPreferredConfig = null;                     b = BitmapManager.instance().decodeFile(f, options);                 } catch (OutOfMemoryError ex)                 {                     Log.e(TAG, "Got oom exception when retry the 2nd time,options.inSampleSize= " + options.inSampleSize                             + " minSideLength = " + minSideLength + " maxNumOfPixels =" + maxNumOfPixels, ex);                     return null;                 }             }         }          //}          return b;     }

//另外一处代码

 public static Bitmap getBitpMap(InputStream is)     {         ParcelFileDescriptor pfd;         try         {             pfd = getContentResolver().openFileDescriptor(uri, "r");         } catch (IOException ex)         {             return null;         }         java.io.FileDescriptor fd = pfd.getFileDescriptor();         BitmapFactory.Options options = new BitmapFactory.Options();         //先指定原始大小            options.inSampleSize = 1;         //只进行大小判断            options.inJustDecodeBounds = true;         //调用此方法得到options得到图片的大小            BitmapFactory.decodeFileDescriptor(fd, null, options);         //BitmapFactory.decodeStream(is, null, options);         //我们的目标是在800pixel的画面上显示。            //所以需要调用computeSampleSize得到图片缩放的比例            options.inSampleSize = computeSampleSize(options, 800);         //OK,我们得到了缩放的比例，现在开始正式读入BitMap数据            options.inJustDecodeBounds = false;         options.inDither = false;         options.inPreferredConfig = Bitmap.Config.ARGB_8888;          //根据options参数，减少所需要的内存            //        Bitmap sourceBitmap = BitmapFactory.decodeFileDescriptor(fd, null, options);         Bitmap sourceBitmap = BitmapFactory.decodeStream(is, null, options);         return sourceBitmap;     }      //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        static int computeSampleSize(BitmapFactory.Options options, int target)     {         int w = options.outWidth;         int h = options.outHeight;         int candidateW = w / target;         int candidateH = h / target;         int candidate = Math.max(candidateW, candidateH);         if (candidate == 0)             return 1;         if (candidate > 1)         {             if ((w > target) && (w / candidate) < target)                 candidate -= 1;         }         if (candidate > 1)         {             if ((h > target) && (h / candidate) < target)                 candidate -= 1;         }         //if (VERBOSE)         Log.v(TAG, "for w/h " + w + "/" + h + " returning " + candidate + "(" + (w / candidate) + " / " + (h / candidate));         return candidate;     }

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