Apache Commons IO has a nice convenience method IOUtils.toString() to read an InputStream to a String.
InputStream
Since I am trying to move away from Apache Common
If you've got a Readable you can use CharStreams.toString(Readable). So you can probably do the following:
Readable
CharStreams.toString(Readable)
String string = CharStreams.toString( new InputStreamReader( inputStream, "UTF-8" ) );
Forces you to specify a character set, which I guess you should be doing anyway.