How to read InputStream

InputStreamReader reader = new InputStreamReader(inputstream );

StringBuilder buf = new StringBuilder();
char[] cbuf = new char[ 2048 ];
int num;

while ( -1 != (num=reader.read( cbuf )))
{
buf.append( cbuf, 0, num );
}

String result = buf.toString();

System.err.println( "\nResponse from server after POST:\n" + result );
reader.close();