即时聊天线程

package test1;import java.io.BufferedReader;  import java.io.IOException;  import java.io.InputStream;  import java.io.InputStreamReader;  import java.io.OutputStream;  import java.io.PrintWriter;  import java.net.Socket;  public class ServerThread extends Thread{//每当侦听到一个新的客户端的时，服务端这边都要有一个Socket与之进行通信      public Socket socket = null;            //默认的构造方法，保留      public ServerThread(){}            //带参构造方法      public ServerThread(Socket socket){          this.socket = socket;      }            //覆写run方法      public void run(){          //获取输入字节流          InputStream in = null;                    //将输入字节流包装成输入字符流          InputStreamReader isr = null;                    //为字符输入流添加缓冲          BufferedReader br = null;                    //收到信息之后，向客户端响应信息,获取输出字节流          OutputStream out = null;                    //将字节输出流包装成字符打印输出流          PrintWriter pw = null;                    try {                            in = socket.getInputStream();              isr = new InputStreamReader(in);              br = new BufferedReader(isr);                            //读取字符输入流中的数据              String data = null;              while((data = br.readLine()) != null){                  System.out.println("我是服务器，客户端说："+data);              }                            //调用shutDown方法关闭Socket输入流              socket.shutdownInput();                            out = socket.getOutputStream();              pw = new PrintWriter(out);              pw.write("用户名和密码正确");              pw.flush();                            //调用shutDown方法关闭Socket输出流              socket.shutdownOutput();                        } catch (IOException e) {              e.printStackTrace();          }finally{                            //关闭资源              try {                  if(null != pw)                      pw.close();                  if(null != out)                      out.close();                  if(null != br)                      br.close();                  if(null != isr)                      isr.close();                  if(null != in)                      in.close();                  if(null != socket)                      socket.close();              } catch (IOException e) {                  e.printStackTrace();              }          }      }  }