InputStream to String

BufferedReader br = new BufferedReader(new InputStreamReader(is));

String line;
while ((line = br.readLine()) != null) {
  System.out.println(line);
}

br.close();

Commons IO:

// build.gradle
compile 'commons-io:commons-io:2.6'
String message = org.apache.commons.io.IOUtils.toString(rd);

Java 8:

rd.lines().collect(Collectors.joining());