read or convert an InputStream into a String in Java?

Question

If you have a 

java.io.InputStream 

object, how should you process that object and produce a String?

Suppose I have an InputStream that contains text data, and I want to convert it to a String, so for example I can write that to a log file.

What is the easiest way to take the InputStream and convert it to a String?

public String convertStreamToString(InputStream is) {

    // ???

}

Answer 1

A nice way to do this is using Apache commons IOUtils to copy the InputStream into a StringWriter... something like

StringWriter writer = new StringWriter();

IOUtils.copy(inputStream, writer, encoding);

String theString = writer.toString();

or even

// NB: does not close inputStream, you'll have to use try-with-resources for that

String theString = IOUtils.toString(inputStream, encoding); 

Alternatively, you could use ByteArrayOutputStream if you don't want to mix your Streams and Writers