How do I use java api to read data from secured hadoop cluster?

[Liu, David]

Hi experts,

Can anyone provide some example or api name to read data from secured hadoop 
cluster?
I have code like this which can read data from unsecured cluster, but when it 
comes to secured one, authentication error will show.
> Configuration conf = new Configuration();
> FileSystem fs = FileSystem.get(URI.create(uri), conf);
> FSDataInputStream in = fs.open(new Path(uri));
> IOUtils.copy(in, System.out, 4096);
> 
> Could anyone help me? Really Appreicate it.
> 
> Thanks