Android中图片过大造成内存溢出，OOM（OutOfMemory）异常解决方法（2）

来源：互联网发布：一落叶而知天下秋编辑：程序博客网时间：2024/06/07 19:48

在Android中：

　　1.一个进程的内存可以由2个部门组成：java 施用内存，C 施用内存，这两个内存的和必需小于16M，不然就会出现各人熟悉的OOM，这个就是熬头种OOM的情况。

　　2.一朝内存分配给Java后，以后这块内存纵然开释后，也只能给Java的施用，这个估计跟java虚拟机里把内存分成好几块进行缓存的原因有关，反正C就别想用到这块的内存了，所以要是Java突然占用了一个大块内存，纵然很快开释了：

　　C能施用的内存 = 16M - Java某一瞬间占在校大学生创业点子用的最大内存。

　　而Bitmap的生成是路程经过过程malloc进行内存分配的，占用的是C的内存。

Code :

/**  * 加载大图片工具类：解决android加载大图片时报OOM异常  * 解决原理：先设置缩放选项，再读取缩放的图片数据到内存，规避了内存引起的OOM  * @author: 张进    * @time:2011/7/28  */  public class BitmapUtil {        public static final int UNCONSTRAINED = -1;            /*   * 获得设置信息   */   public static Options getOptions(String path){    Options options = new Options();    options.inJustDecodeBounds = true;//只描边，不读取数据     BitmapFactory.decodeFile(path, options);    return options;   }         /**   * 获得图像   * @param path   * @param options   * @return   * @throws FileNotFoundException   */   public static Bitmap getBitmapByPath(String path, Options options , int screenWidth , int screenHeight)throws FileNotFoundException{    File file = new File(path);    if(!file.exists()){     throw new FileNotFoundException();    }    FileInputStream in = null;    in = new FileInputStream(file);    if(options != null){     Rect r = getScreenRegion(screenWidth,screenHeight);     int w = r.width();     int h = r.height();     int maxSize = w > h ? w : h;     int inSimpleSize = computeSampleSize(options, maxSize, w * h);     options.inSampleSize = inSimpleSize; //设置缩放比例      options.inJustDecodeBounds = false;    }    Bitmap b = BitmapFactory.decodeStream(in, null, options);    try {     in.close();    } catch (IOException e) {     e.printStackTrace();    }    return b;   }               private static Rect getScreenRegion(int width , int height) {    return new Rect(0,0,width,height);   }       /**   * 获取需要进行缩放的比例，即options.inSampleSize   * @param options   * @param minSideLength   * @param maxNumOfPixels   * @return   */   public static int computeSampleSize(BitmapFactory.Options options,              int minSideLength, int maxNumOfPixels) {          int initialSize = computeInitialSampleSize(options, minSideLength,                  maxNumOfPixels);            int roundedSize;          if (initialSize <= 8) {              roundedSize = 1;              while (roundedSize < initialSize) {                  roundedSize <<= 1;              }          } else {              roundedSize = (initialSize + 7) / 8 * 8;          }            return roundedSize;      }        private static int computeInitialSampleSize(BitmapFactory.Options options,              int minSideLength, int maxNumOfPixels) {          double w = options.outWidth;          double h = options.outHeight;            int lowerBound = (maxNumOfPixels == UNCONSTRAINED) ? 1 :                  (int) Math.ceil(Math.sqrt(w * h / maxNumOfPixels));          int upperBound = (minSideLength == UNCONSTRAINED) ? 128 :                  (int) Math.min(Math.floor(w / minSideLength),                  Math.floor(h / minSideLength));            if (upperBound < lowerBound) {              // return the larger one when there is no overlapping zone.               return lowerBound;          }            if ((maxNumOfPixels == UNCONSTRAINED) &&                  (minSideLength == UNCONSTRAINED)) {              return 1;          } else if (minSideLength == UNCONSTRAINED) {              return lowerBound;          } else {              return upperBound;          }      }           }

工具类的使用：

String path = "/sdcard/test2.jpg";      try {    Bitmap bitmap = BitmapUtil.getBitmapByPath(path, BitmapUtil.getOptions(path), screenWidth, screenHeight);   } catch (FileNotFoundException e) {    e.printStackTrace();   }

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