直接粘贴就能用

  private Bitmap ImageSizeCompress(Uri uri){
        InputStream Stream = null;
        InputStream inputStream = null;
        try {
            //根据uri获取图片的流
            inputStream = getContentResolver().openInputStream(uri);
            BitmapFactory.Options options = new BitmapFactory.Options();
            //options的in系列的设置了，injustdecodebouond只解析图片的大小，而不加载到内存中去
            options.inJustDecodeBounds = true;
            //1.如果通过options.outHeight获取图片的宽高，就必须通过decodestream解析同options赋值
            //否则options.outheight获取不到宽高
            BitmapFactory.decodeStream(inputStream,null,options);
            //2.通过 btm.getHeight()获取图片的宽高就不需要1的解析，我这里采取第一张方式
//            Bitmap btm = BitmapFactory.decodeStream(inputStream);
            //以屏幕的宽高进行压缩
            DisplayMetrics displayMetrics = getResources().getDisplayMetrics();
            int heightPixels = displayMetrics.heightPixels;
            int widthPixels = displayMetrics.widthPixels;
            //获取图片的宽高
            int outHeight = options.outHeight;
            int outWidth = options.outWidth;
            //heightPixels就是要压缩后的图片高度，宽度也一样
            int a = (int) Math.ceil((outHeight/(float)heightPixels));
            int b = (int) Math.ceil(outWidth/(float)widthPixels);
            //比例计算,一般是图片比较大的情况下进行压缩
            int max = Math.max(a, b);
            if(max > 1){
                options.inSampleSize = max;
            }
            //解析到内存中去
            options.inJustDecodeBounds = false;
//            根据uri重新获取流，inputstream在解析中发生改变了
            Stream = getContentResolver().openInputStream(uri);
            Bitmap bitmap = BitmapFactory.decodeStream(Stream, null, options);
            return bitmap;
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            try {
                if(inputStream != null) {
                    inputStream.close();
                }
                if(Stream != null){
                    Stream.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
        return  null;
    }

引用

  Bitmap bitmap = ImageSizeCompress(uri);