Easy way to write contents of a Java InputStream to an OutputStream

As WMR mentioned, org.apache.commons.io.IOUtils from Apache has a method called copy(InputStream,OutputStream) which does exactly what you're looking for.

So, you have:

InputStream in;
OutputStream out;
IOUtils.copy(in,out);
in.close();
out.close();

...in your code.

Is there a reason you're avoiding IOUtils?

If you are using Java 7, Files (in the standard library) is the best approach:

/* You can get Path from file also: file.toPath() */
Files.copy(InputStream in, Path target)
Files.copy(Path source, OutputStream out)

Edit: Of course it's just useful when you create one of InputStream or OutputStream from file. Use file.toPath() to get path from file.

To write into an existing file (e.g. one created with File.createTempFile()), you'll need to pass the REPLACE_EXISTING copy option (otherwise FileAlreadyExistsException is thrown):

Files.copy(in, target, StandardCopyOption.REPLACE_EXISTING)