根据输入流获得字节数组

public static byte[] read(InputStream in) throws IOException{
  byte[] arr=new byte[1024];
  ByteArrayOutputStream out=new ByteArrayOutputStream();
  int len=0;
  while((len=in.read(arr))!=-1){
   out.write(arr, 0, len);
  }
  out.close();
  return out.toByteArray();
 }