java转换为Base64，结果为reapeat？

Question

我在安卓中获取url，并使用以下代码将数据流转换为64位数据字符串：

URL url = new URL("http://iranassistance.com/images/sos-logo.png");
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
//urlConnection.setDoOutput(true);
urlConnection.connect();
File SDCardRoot = Environment.getExternalStorageDirectory().getAbsoluteFile();
String filename="downloadedFile.png";
Log.i("Local filename:",""+filename);
File file = new File(SDCardRoot,filename);
if(file.createNewFile()) {
  file.createNewFile();
}
FileOutputStream fileOutput = new FileOutputStream(file);
InputStream inputStream = urlConnection.getInputStream();byte[] imageBytes = new byte[urlConnection.getContentLength()];
inputStream.read(imageBytes, 0, imageBytes.length);
inputStream.close();
String base64Image = Base64.encodeToString(imageBytes, Base64.DEFAULT);

但是base64Image的结果并不完整，给出了如下结果：

......nUTJaJnb7PLyscfBMQLLiexyKSEh/o2RfctcZtc8Hr5xcAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA........

重复的“A”表示有问题，图像不完整！为什么这不能正常工作