每日总结

利用android系统压缩方式进行图片压缩，代码：

private String path = "/sdcard/img.jpg";
File f = new File(path);
Bitmap bm = PictureUtil.getSmallBitmap(this,path);
FileOutputStream fos;
    try {
        fos = new FileOutputStream(new File("/sdcard/", "small_" + f.getName()));
        bm.compress(Bitmap.CompressFormat.JPEG, 90, fos);
    } catch (FileNotFoundException e) {
        e.printStackTrace();
        }        

getSmallBitmap方法是根据路径获得图片并压缩返回bitmap用于显示。

    /**
     * 计算图片的缩放值
     * 
     * @param options
     * @param reqWidth
     * @param reqHeight
     * @return
     */
    public static int calculateInSampleSize(BitmapFactory.Options options,
            int reqWidth, int reqHeight) {
        // Raw height and width of image
        final int height = options.outHeight;
        final int width = options.outWidth;
        int inSampleSize = 1;

        if (height > reqHeight || width > reqWidth) {

            // Calculate ratios of height and width to requested height and
            // width
            final int heightRatio = Math.round((float) height
                    / (float) reqHeight);
            final int widthRatio = Math.round((float) width / (float) reqWidth);

            // Choose the smallest ratio as inSampleSize value, this will
            // guarantee
            // a final image with both dimensions larger than or equal to the
            // requested height and width.
            inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
        }

        return inSampleSize;
    }

    

    
    /**
     * 根据路径获得图片并压缩返回bitmap用于显示
     * 
     * @param imagesrc
     * @return
     */
    public static Bitmap getSmallBitmap(Context context ,String filePath) {
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeFile(filePath, options);

        DisplayMetrics dm = context.getResources().getDisplayMetrics();
        
        // Calculate inSampleSize
        options.inSampleSize = calculateInSampleSize(options, dm.widthPixels, dm.heightPixels);

        // Decode bitmap with inSampleSize set
        options.inJustDecodeBounds = false;

        return BitmapFactory.decodeFile(filePath, options);
    }