Android图像质量缩放后无需保留

我从服务器获取图像，缩放后图像质量无法保留。下面是我的代码，请帮助我保持图像的质量

private Bitmap decodeFile1(File f){
        try {
            //decode image size
            BitmapFactory.Options o = new BitmapFactory.Options();
            o.inJustDecodeBounds = true;
            o.inScaled = false;
            o.inDither = false;
            o.inPreferredConfig = Bitmap.Config.ARGB_8888;
            BitmapFactory.decodeStream(new FileInputStream(f),null,o);              
            //Find the correct scale value. It should be the power of 2.
            final int REQUIRED_SIZE=70;
            int width_tmp=o.outWidth, height_tmp=o.outHeight;
            int scale=1;
            while(true){
                if(width_tmp/2<REQUIRED_SIZE || height_tmp/2<REQUIRED_SIZE)
                    break;
                width_tmp/=2;
                height_tmp/=2;
                scale++;
            }


            BitmapFactory.Options o2 = new BitmapFactory.Options();
            o2.inPreferredConfig = Bitmap.Config.ARGB_8888;
            o2.inSampleSize=scale;
            o2.inScaled = false;
            o2.inDither = false;
            return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
        } catch (FileNotFoundException e) {}
        return null;
    }

私有位图解码文件1（文件f）{
试一试{
//解码图像大小
BitmapFactory.Options o=新的BitmapFactory.Options（）；
o、 inJustDecodeBounds=true；
o、 inScaled=假；
o、 inDither=假；
o、 inPreferredConfig=Bitmap.Config.ARGB_8888；
解码流（新的FileInputStream（f），null，o）；
//找到正确的刻度值。它应该是2的幂。
所需的最终int_尺寸=70；
内部宽度=o.向外宽度，高度=o.向外高度；
int标度=1；
while（true）{
如果（宽度_tmp/2您可以使用以下代码

//decodes image and scales it to reduce memory consumption
    private Bitmap decodeFile(File f){
        try {
            //decode image size
            BitmapFactory.Options o = new BitmapFactory.Options();
            o.inJustDecodeBounds = true;
            FileInputStream stream1=new FileInputStream(f);
            BitmapFactory.decodeStream(stream1,null,o);
            stream1.close();

            //Find the correct scale value. It should be the power of 2.
            final int REQUIRED_SIZE=1024;
            int width_tmp=o.outWidth, height_tmp=o.outHeight;
            int scale=1;
            while(true){
                if(width_tmp/2<REQUIRED_SIZE || height_tmp/2<REQUIRED_SIZE)
                    break;
                width_tmp/=2;
                height_tmp/=2;
                scale*=2;
            }

            //decode with inSampleSize
            BitmapFactory.Options o2 = new BitmapFactory.Options();
            o2.inSampleSize=scale;
            FileInputStream stream2=new FileInputStream(f);
            Bitmap bitmap=BitmapFactory.decodeStream(stream2, null, o2);
            stream2.close();
            return bitmap;
        } catch (FileNotFoundException e) {
        } 
        catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }

final int REQUIRED_SIZE=1024; //Increase its value to get quality image but remember it should be the power of 2.