基于心跳的socket长连接

案例： 
心跳： 
socket模拟网页的报文连接某个网站，创建tcp的socket后，当我socket.connect后，如果在5到7秒钟不socket.send，那么这个链接就失效了。 请问如何长时间的保持这个链接 
这是在服务器端的设置的，客户端没法设置,可以发送心跳包。 
socket.connect后，每3-4秒用socket.send发送一字节数据（内容随便），然后观查这个连接是否保持。 

lientSocket=serverSocket.accept(); 
OutputStream os = clientSocket.getOutputStream();           
ObjectOutputStream oos=new ObjectOutputStream(os); 
oos.writeObject(al); 
oos.flush(); 
oos.close()//socket会关闭 

实现： 
长连接的维持，是要客户端程序，定时向服务端程序，发送一个维持连接包的。 
如果，长时间未发送维持连接包，服务端程序将断开连接。 

客户端： 
通过持有Client对象，可以随时（使用sendObject方法）发送Object给服务端。 
如果keepAliveDelay毫秒（程序中是2秒）内未发送任何数据，则，自动发送一个KeepAlive对象给服务端， 
用于维持连接。 
由于，我们向服务端，可以发送很多不同的对象，服务端也可以返回不同的对象。 
所以，对于返回对象的处理，要编写具体的ObjectAction实现类进行处理。 
通过Client.addActionMap方法进行添加。这样，程序会回调处理。 

服务端： 
由于客户端会定时（keepAliveDelay毫秒）发送维持连接的信息过来，所以，服务端要有一个检测机制。 
即当服务端receiveTimeDelay毫秒（程序中是3秒）内未接收任何数据，则，自动断开与客户端的连接。 
ActionMapping的原理与客户端相似（相同）。 
通过添加相应的ObjectAction实现类，可以实现不同对象的响应、应答过程。 

Java代码   

1. package houlei.csdn.keepalive;  
2.   
3. import java.io.Serializable;  
4. import java.text.SimpleDateFormat;  
5. import java.util.Date;  
6.   
7. /** 
8.  * 维持连接的消息对象。 
9.  */  
10. public class KeepAlive implements Serializable{  
11.   
12.     private static final long serialVersionUID = -2813120366138988480L;  
13.   
14.     /* 覆盖该方法，仅用于测试使用。 
15.      * @see java.lang.Object#toString() 
16.      */  
17.     @Override  
18.     public String toString() {  
19.         return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date())+"\t维持连接包";  
20.     }  
21.   
22. }  

client: 

Java代码   

1. package houlei.csdn.keepalive;  
2.   
3. import java.io.IOException;  
4. import java.io.InputStream;  
5. import java.io.ObjectInputStream;  
6. import java.io.ObjectOutputStream;  
7. import java.net.Socket;  
8. import java.net.UnknownHostException;  
9. import java.util.concurrent.ConcurrentHashMap;  
10.   
11. /** 
12.  *  C/S架构的客户端对象，持有该对象，可以随时向服务端发送消息。 
13.  */  
14. public class Client {  
15.   
16.     /** 
17.      * 处理服务端发回的对象，可实现该接口。 
18.      */  
19.     public static interface ObjectAction{  
20.         void doAction(Object obj,Client client);  
21.     }  
22.     public static final class DefaultObjectAction implements ObjectAction{  
23.         public void doAction(Object obj,Client client) {  
24.             System.out.println("处理：\t"+obj.toString());  
25.         }  
26.     }  
27.     public static void main(String[] args) throws UnknownHostException, IOException {  
28.         String serverIp = "127.0.0.1";  
29.         int port = 65432;  
30.         Client client = new Client(serverIp,port);  
31.         client.start();  
32.     }  
33.       
34.     private String serverIp;  
35.     private int port;  
36.     private Socket socket;  
37.     private boolean running=false;  
38.     private long lastSendTime;  
39.     private ConcurrentHashMap<Class, ObjectAction> actionMapping = new ConcurrentHashMap<Class,ObjectAction>();  
40.       
41.     public Client(String serverIp, int port) {  
42.         this.serverIp=serverIp;this.port=port;  
43.     }  
44.       
45.     public void start() throws UnknownHostException, IOException {  
46.         if(running)return;  
47.         socket = new Socket(serverIp,port);  
48.         System.out.println("本地端口："+socket.getLocalPort());  
49.         lastSendTime=System.currentTimeMillis();  
50.         running=true;  
51.         new Thread(new KeepAliveWatchDog()).start();  
52.         new Thread(new ReceiveWatchDog()).start();  
53.     }  
54.       
55.     public void stop(){  
56.         if(running)running=false;  
57.     }  
58.       
59.     /** 
60.      * 添加接收对象的处理对象。 
61.      * @param cls 待处理的对象，其所属的类。 
62.      * @param action 处理过程对象。 
63.      */  
64.     public void addActionMap(Class<Object> cls,ObjectAction action){  
65.         actionMapping.put(cls, action);  
66.     }  
67.   
68.     public void sendObject(Object obj) throws IOException {  
69.         ObjectOutputStream oos = new ObjectOutputStream(socket.getOutputStream());  
70.         oos.writeObject(obj);  
71.         System.out.println("发送：\t"+obj);  
72.         oos.flush();  
73.     }  
74.       
75.     class KeepAliveWatchDog implements Runnable{  
76.         long checkDelay = 10;  
77.         long keepAliveDelay = 2000;  
78.         public void run() {  
79.             while(running){  
80.                 if(System.currentTimeMillis()-lastSendTime>keepAliveDelay){  
81.                     try {  
82.                         Client.this.sendObject(new KeepAlive());  
83.                     } catch (IOException e) {  
84.                         e.printStackTrace();  
85.                         Client.this.stop();  
86.                     }  
87.                     lastSendTime = System.currentTimeMillis();  
88.                 }else{  
89.                     try {  
90.                         Thread.sleep(checkDelay);  
91.                     } catch (InterruptedException e) {  
92.                         e.printStackTrace();  
93.                         Client.this.stop();  
94.                     }  
95.                 }  
96.             }  
97.         }  
98.     }  
99.       
100.     class ReceiveWatchDog implements Runnable{  
101.         public void run() {  
102.             while(running){  
103.                 try {  
104.                     InputStream in = socket.getInputStream();  
105.                     if(in.available()>0){  
106.                         ObjectInputStream ois = new ObjectInputStream(in);  
107.                         Object obj = ois.readObject();  
108.                         System.out.println("接收：\t"+obj);  
109.                         ObjectAction oa = actionMapping.get(obj.getClass());  
110.                         oa = oa==null?new DefaultObjectAction():oa;  
111.                         oa.doAction(obj, Client.this);  
112.                     }else{  
113.                         Thread.sleep(10);  
114.                     }  
115.                 } catch (Exception e) {  
116.                     e.printStackTrace();  
117.                     Client.this.stop();  
118.                 }   
119.             }  
120.         }  
121.     }  
122.       
123. }  

server: 

Java代码   

1. package houlei.csdn.keepalive;  
2.   
3.   
4. import java.io.IOException;  
5. import java.io.InputStream;  
6. import java.io.ObjectInputStream;  
7. import java.io.ObjectOutputStream;  
8. import java.net.ServerSocket;  
9. import java.net.Socket;  
10. import java.util.concurrent.ConcurrentHashMap;  
11.   
12. /** 
13.  * C/S架构的服务端对象。 
14.  */  
15. public class Server {  
16.   
17.     /** 
18.      * 要处理客户端发来的对象，并返回一个对象，可实现该接口。 
19.      */  
20.     public interface ObjectAction{  
21.         Object doAction(Object rev);  
22.     }  
23.       
24.     public static final class DefaultObjectAction implements ObjectAction{  
25.         public Object doAction(Object rev) {  
26.             System.out.println("处理并返回："+rev);  
27.             return rev;  
28.         }  
29.     }  
30.       
31.     public static void main(String[] args) {  
32.         int port = 65432;  
33.         Server server = new Server(port);  
34.         server.start();  
35.     }  
36.       
37.     private int port;  
38.     private volatile boolean running=false;  
39.     private long receiveTimeDelay=3000;  
40.     private ConcurrentHashMap<Class, ObjectAction> actionMapping = new ConcurrentHashMap<Class,ObjectAction>();  
41.     private Thread connWatchDog;  
42.       
43.     public Server(int port) {  
44.         this.port = port;  
45.     }  
46.   
47.     public void start(){  
48.         if(running)return;  
49.         running=true;  
50.         connWatchDog = new Thread(new ConnWatchDog());  
51.         connWatchDog.start();  
52.     }  
53.       
54.     @SuppressWarnings("deprecation")  
55.     public void stop(){  
56.         if(running)running=false;  
57.         if(connWatchDog!=null)connWatchDog.stop();  
58.     }  
59.       
60.     public void addActionMap(Class<Object> cls,ObjectAction action){  
61.         actionMapping.put(cls, action);  
62.     }  
63.       
64.     class ConnWatchDog implements Runnable{  
65.         public void run(){  
66.             try {  
67.                 ServerSocket ss = new ServerSocket(port,5);  
68.                 while(running){  
69.                     Socket s = ss.accept();  
70.                     new Thread(new SocketAction(s)).start();  
71.                 }  
72.             } catch (IOException e) {  
73.                 e.printStackTrace();  
74.                 Server.this.stop();  
75.             }  
76.               
77.         }  
78.     }  
79.       
80.     class SocketAction implements Runnable{  
81.         Socket s;  
82.         boolean run=true;  
83.         long lastReceiveTime = System.currentTimeMillis();  
84.         public SocketAction(Socket s) {  
85.             this.s = s;  
86.         }  
87.         public void run() {  
88.             while(running && run){  
89.                 if(System.currentTimeMillis()-lastReceiveTime>receiveTimeDelay){  
90.                     overThis();  
91.                 }else{  
92.                     try {  
93.                         InputStream in = s.getInputStream();  
94.                         if(in.available()>0){  
95.                             ObjectInputStream ois = new ObjectInputStream(in);  
96.                             Object obj = ois.readObject();  
97.                             lastReceiveTime = System.currentTimeMillis();  
98.                             System.out.println("接收：\t"+obj);  
99.                             ObjectAction oa = actionMapping.get(obj.getClass());  
100.                             oa = oa==null?new DefaultObjectAction():oa;  
101.                             Object out = oa.doAction(obj);  
102.                             if(out!=null){  
103.                                 ObjectOutputStream oos = new ObjectOutputStream(s.getOutputStream());  
104.                                 oos.writeObject(out);  
105.                                 oos.flush();  
106.                             }  
107.                         }else{  
108.                             Thread.sleep(10);  
109.                         }  
110.                     } catch (Exception e) {  
111.                         e.printStackTrace();  
112.                         overThis();  
113.                     }   
114.                 }  
115.             }  
116.         }  
117.           
118.         private void overThis() {  
119.             if(run)run=false;  
120.             if(s!=null){  
121.                 try {  
122.                     s.close();  
123.                 } catch (IOException e) {  
124.                     e.printStackTrace();  
125.                 }  
126.             }  
127.             System.out.println("关闭："+s.getRemoteSocketAddress());  
128.         }  
129.           
130.     }  
131.       
132. }  
133.   转载自：http://coach.iteye.com/blog/2024444