Android本地图片压缩+转base64

 // 根据路径获得图片并压缩，返回bitmap用于显示
    private static Bitmap getSmallBitmap(String filePath) {
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeFile(filePath, options);

        // Calculate inSampleSize
        options.inSampleSize = calculateInSampleSize(options, 480, 800);

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

        return BitmapFactory.decodeFile(filePath, options);
    }

    //计算图片的缩放值
    private static int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
        final int height = options.outHeight;
        final int width = options.outWidth;
        int inSampleSize = 1;

        if (height > reqHeight || width > reqWidth) {
            final int heightRatio = Math.round((float) height / (float) reqHeight);
            final int widthRatio = Math.round((float) width / (float) reqWidth);
            inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
        }
        return inSampleSize;
    }


    //把bitmap转换成String
    public static String bitmapToString(String filePath) {
        Bitmap bm = getSmallBitmap(filePath);
        ByteArrayOutputStream baos = new ByteArrayOutputStream();

        //1.5M的压缩后在100Kb以内，测试得值,压缩后的大小=94486字节,压缩后的大小=74473字节
        //这里的JPEG 如果换成PNG，那么压缩的就有600kB这样
        bm.compress(Bitmap.CompressFormat.JPEG, 40, baos);
        byte[] b = baos.toByteArray();
        Log.d("d", "压缩后的大小=" + b.length);
        return "data:img/jpg;base64," + Base64.encodeToString(b, Base64.DEFAULT);
    }

调用

String base64str = bitmapToString(path);//path 图片路径