上傳圖片壓縮工具類

1、校驗圖片角度，有旋轉進行修改；然後校驗圖片大小，大於標清(720*1280)進行壓縮；調用下面該方法傳入需要壓縮的圖片文件，返回壓縮後的圖片文件；方法調用需要運行在子線程中進行

public File getModificationFile(File file){
		file=reviewPicRotate(file);
		if(verifyPictureSize(file.getPath())){//標清不壓縮
			return file;
		}else{//壓縮
			File compressionFile = saveBitmapToLocal(getBitmapFromFile(file.getPath()));
			if(compressionFile == null)
				return file;
			return compressionFile;
		}
	}

2、獲取圖片文件的信息，判斷是否旋轉矯正

public File reviewPicRotate(File file){
		//讀取圖片文件旋轉的角度
		int degree  = 0;
		try {
			ExifInterface exifInterface = new ExifInterface(file.getPath());
			int orientation = exifInterface.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_NORMAL);
			switch (orientation) {
			case ExifInterface.ORIENTATION_ROTATE_90:
				degree = 90;
				break;
			case ExifInterface.ORIENTATION_ROTATE_180:
				degree = 180;
				break;
			case ExifInterface.ORIENTATION_ROTATE_270:
				degree = 270;
				break;
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
		if(degree != 0){//圖片旋轉了；進行圖片旋轉
			Bitmap bitmap = getBitmapFromFile(file.getPath());
			Matrix m = new Matrix();  
			int width = bitmap.getWidth();  
			int height = bitmap.getHeight();  
			m.setRotate(degree); // 旋轉angle度  
			bitmap = Bitmap.createBitmap(bitmap, 0, 0, width, height,m, true);
			return saveBitmapToLocal(bitmap);// 從新生成圖片文件
		}
		return file;
	}

3、判斷圖片如果小於720 * 1280直接返回原圖片文件，否則壓縮

public static boolean verifyPictureSize(String path) {
	        BitmapFactory.Options opts = new BitmapFactory.Options();
	        opts.inJustDecodeBounds = true;
	        BitmapFactory.decodeFile(path, opts);
	        if (opts.outHeight <= 1280 && opts.outWidth <= 720)
	            return true;
	        else return false;
	    }	

4、將文件轉換爲720*1280的bitmap

public static Bitmap getBitmapFromFile(String path) {
		 int width = 720;
	     int height = 1280;
	     BitmapFactory.Options opts = null;
	     if(path != null) {
	          if (width > 0 && height > 0) {
	              opts = new BitmapFactory.Options();
	              opts.inJustDecodeBounds = true;
	              BitmapFactory.decodeFile(path, opts);
	              final int minSideLength = Math.min(width, height);
	              opts.inSampleSize = computeSampleSize(opts, minSideLength,width * height);
	              opts.inJustDecodeBounds = false;
	          }
	          return BitmapFactory.decodeFile(path, opts);
	      } else return null;
	  }

5、計算壓縮比率

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 == -1) ? 1 : (int) Math.ceil(Math.sqrt(w * h / maxNumOfPixels));
	        int upperBound = (minSideLength == -1) ? 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 == -1) && (minSideLength == -1)) {
	            return 1;
	        } else if (minSideLength == -1) {
	            return lowerBound;
	        } else {
	            return upperBound;
	        }
	    }

6、將轉換後的bitmap對象保存爲file文件並存儲到本地

public File saveBitmapToLocal(Bitmap bitmap) {
	        if (null == bitmap) {
	            return null;
	        }
	        FileOutputStream fileOutput = null;
	        File imgFile = null;
	        try {
	            imgFile = SDUtils.getCreatFile(context,SDUtils.imgCachePicUrl, System.currentTimeMillis()+".jpg");//新創建的圖片文件對象
	            fileOutput = new FileOutputStream(imgFile);
	            bitmap.compress(Bitmap.CompressFormat.JPEG, 90, fileOutput);
	            fileOutput.flush();
	        } catch (FileNotFoundException e) {
	            e.printStackTrace();
	            imgFile = null;
	        } catch (IOException e) {
	            e.printStackTrace();
	            imgFile = null;
	        } finally {
	            if (null != fileOutput) {
	                try {
	                    fileOutput.close();
	                } catch (IOException e) {
	                    e.printStackTrace();
	                }
	            }
	        }
	        return imgFile;
	    }