在Android中,对图片使用的内存是有限制的,加载的图片过大便出导致OOM问题。图像在加载过程中,是把所有像素(即长*宽)加载到内存中,如果图片过大,便会导致java.lang.OutOfMemoryError问题,因此,在使用时要要加以注意。
private static int MAX_IMAGE_DIMENSION = 720; public Bitmap decodeFile(String filePath) throws IOException { Uri photoUri = Uri.parse(filePath); InputStream is = this.getContentResolver().openInputStream(photoUri); BitmapFactory.Options dbo = new BitmapFactory.Options(); dbo.inJustDecodeBounds = true; BitmapFactory.decodeStream(is, null, dbo); is.close(); int rotatedWidth, rotatedHeight; rotatedWidth = dbo.outWidth; rotatedHeight = dbo.outHeight; Bitmap mCurrentBitmap = null; is = this.getContentResolver().openInputStream(photoUri); if (rotatedWidth > MAX_IMAGE_DIMENSION || rotatedHeight > MAX_IMAGE_DIMENSION) { float widthRatio = ((float) rotatedWidth) / MAX_IMAGE_DIMENSION; float heightRatio = ((float) rotatedHeight) / MAX_IMAGE_DIMENSION; float maxRatio = Math.max(widthRatio, heightRatio); // Create the bitmap from file BitmapFactory.Options options = new BitmapFactory.Options(); // 1.换算合适的图片缩放值,以减少对JVM太多的内存请求。 options.inSampleSize = (int) maxRatio; // 2. inPurgeable 设定为 true,可以让java系统, 在内存不足时先行回收部分的内存 options.inPurgeable = true; // 与inPurgeable 一起使用 options.inInputShareable = true; // 3. 减少对Aphla 通道 options.inPreferredConfig = Bitmap.Config.RGB_565; try { // 4. inNativeAlloc 属性设置为true,可以不把使用的内存算到VM里 BitmapFactory.Options.class.getField("inNativeAlloc").setBoolean(options, true); } catch (IllegalArgumentException e) { e.printStackTrace(); } catch (SecurityException e) { e.printStackTrace(); } catch (IllegalAccessException e) { e.printStackTrace(); } catch (NoSuchFieldException e) { e.printStackTrace(); } // 5. 使用decodeStream 解码,则利用NDK层中,利用nativeDecodeAsset() // 进行解码,不用CreateBitmap mCurrentBitmap = BitmapFactory.decodeStream(is, null, options); } else { mCurrentBitmap = BitmapFactory.decodeStream(is); } return mCurrentBitmap; }