Java中的线程如何实现通过关闭Socket终止

package Threads;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.net.Socket;public class StopClose extends Thread {  protected Socket io;  public void run() {    try {      io = new Socket("java.sun.com", 80);      BufferedReader is = new BufferedReader(new InputStreamReader(io.getInputStream()));      System.out.println("StopClose reading");            String line = is.readLine();            System.out.printf("StopClose FINISHED after reading %s!", line);    } catch (IOException ex) {      System.out.println("StopClose terminating:" + ex);    }  }  public void shutDown() throws IOException {    if (io != null) {      synchronized (io) {        io.close();      }    }    System.out.println("StopClose.shutDown() complete");  }  public static void main(String[] args) throws InterruptedException, IOException {    StopClose t = new StopClose();    t.start();    sleep(1000*5);    t.shutDown();  }}