java PipedInputStream和PipedOutputStream用法

import java.io.PipedInputStream;
import java.io.PipedOutputStream;
import java.io.InputStream;
import java.io.DataInputStream;

class ChildThread extends Thread
{
        private PipedInputStream in;

        public ChildThread(PipedInputStream in)
        {
                this.in = in;
        }

        private void readPipe() throws Exception
        {
                byte[] data = new byte[1024];
                int len;

                while (true)
                {
                        len = in.read(data, 0, data.length);
                        if (len == -1)
                                break;
                        else
                                System.out.println(new String(data, 0, len));
                }
        }

        public void run()
        {
                try
                {
                        readPipe();
                }
                catch(Exception e)
                {
                        e.printStackTrace();
                }
        }
}

public final class tmp
{
        public static void main(String args[]) throws Exception
        {
                PipedInputStream in = new PipedInputStream();
                PipedOutputStream out = new PipedOutputStream();

                in.connect(out);

                ChildThread t = new ChildThread(in);
                t.start();

                byte[] data = new byte[1024];
                int len;

                InputStream reader = new DataInputStream(System.in);

                while (true)
                {
                        len = reader.read(data, 0, data.length);
                        if (len == -1)
                                break;
                        else
                                out.write(data, 0, len);
                }

                out.flush();
                out.close();
                in.close();
        }
}