前言

在將圖片加載到內存時，都要去做一個縮放，通過設置inJustDecodeBounds = true這樣就只解析out屬性，當我們要把options配置信息重新傳給decodeStream時，返回的bitmap為空，這是因為inputStream被調用了兩次，第二次已經(jīng)清空。

解決方案

1.將輸入流轉為為字節(jié)數(shù)組。

  private byte[] inputStream2ByteArr(InputStream inputStream) throws IOException {
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        byte[] buff = new byte[1024];
        int len = 0;
        while ((len = inputStream.read(buff)) != -1) {
            outputStream.write(buff, 0, len);
        }
        inputStream.close();
        outputStream.close();
        return outputStream.toByteArray();
    }

2.調用decodeByteArray來解析字節(jié)數(shù)組。

 byte[] inputStream2ByteArr = inputStream2ByteArr(inputStream);
                //TODO 網(wǎng)絡上獲取圖片 模擬接收過程。

                BitmapFactory.Options options = new BitmapFactory.Options();
                options.inJustDecodeBounds = true;

                BitmapFactory.decodeByteArray(inputStream2ByteArr,0,inputStream2ByteArr.length,options);

                int w = options.outWidth;
                int h = options.outHeight;

                options.inSampleSize = caculateInsampleSize(w,h,80,80);

                options.inJustDecodeBounds = false;

                options.inMutable =true;
                options.inBitmap = reusable;

                final Bitmap bitmap =  BitmapFactory.decodeByteArray(inputStream2ByteArr,0,inputStream2ByteArr.length,options);