socket服务器推送技术

package duisong;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Timer;

/**
* @author Administrator
*
*/
public class Server {
private int PORT = 9000;
private ServerSocket ss = null;
private Timer timer = new Timer();

public Server() {
try {
ss = new ServerSocket(PORT);
System.out.println("server start");
} catch (IOException e) {
e.printStackTrace();
}
}

/**
* @param args
*/
public static void main(String[] args) {
Server server = new Server();
server.startup();

}

public void startup() {
Socket s = null;
while (true) {
try {
s = ss.accept();
Handler handler = new Handler(s);
timer.schedule(handler, 1000, 3000);
} catch (IOException e) {
e.printStackTrace();
System.out.println(e.getMessage());
}
}
}
}


-----------------------

package duisong;

import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Date;
import java.util.TimerTask;

/**
* @author Administrator
*
*/
public class Handler extends TimerTask {
private Socket socket;

public Handler(Socket socket) {
this.socket = socket;

}

@Override
public void run() {
String nowTime = (new Date()).toLocaleString();
try {
if (socket != null && socket.isConnected()) {
// 这里打个擦边球，先发送个紧急的数据包，如果发送发送了异常，说明客户端已经关闭了socket连接了，进入异常处理程序
socket.sendUrgentData(0xFF);
System.out.println(nowTime);
PrintWriter pw = new PrintWriter(new OutputStreamWriter(socket
.getOutputStream()));
pw.append(nowTime);
pw.append("\r");
pw.flush();
}
} catch (IOException e) {
try {
e.printStackTrace();
socket.close();
} catch (IOException e2) {
}
this.cancel();
}

}

}

------------------------
package duisong;

import java.applet.Applet;
import java.awt.Label;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.Socket;

/**
* 此程序eclipse运行良好，但是在IE中引入该Applet就出错了，提示access denied
* 是由于客户端的安全策略引起的，看来还是要用flash比较靠谱
*
*/
public class SocketApplet extends Applet implements Runnable {
Label text = new Label();
private Socket socket;
private BufferedReader br;

public SocketApplet() {

}

public void init() {
text.setText("time begin");
add(text);
try {
socket = new Socket("127.0.0.1", 9000);
br = new BufferedReader(new InputStreamReader(socket
.getInputStream()));
text.setText("socket setup ok ...");
// 初始化完毕，启动线程处理
new Thread(this).start();
} catch (Exception e) {

text.setText(e.getMessage());
}
}

public void run() {
while (true) {
try {
text.setText(br.readLine());
} catch (IOException e) {

}
}
}

}


1.server端监听9000端口，如果client端有加入
  s = ss.accept();继续执行，进而执行逻辑，向client端口输出数据，
  否则，stop here

2.client端可以设计线程池，有序列的向服务器端发送请求。
  减少并发性操作服务器