// что это while((line=br.readLine())1=null)
if(response!=null){
sb = new StringBuilder();
byte[] buffer = new byte[512];
int bytes_read = 0;
while((bytes_read = is.read(buffer, 0, buffer.length)) > 0)
{
sb.append( new String(buffer,0,bytes_read));
}
System.out.println("Preview image Result=="+sb.toString());
}