基于心跳的socket长连接

基于心跳的socket长连接

原文 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

package socketConnection;

import java.io.Serializable;
import java.text.SimpleDateFormat;
import java.util.Date;

public class KeepAlive
implements Serializable {

private static final long serialVersionUID = 4735076043744002795L;

@Override
public String toString() {
return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date()+"\t维持连接包");
}
}

client：

java代码

package socketConnection;

import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.concurrent.ConcurrentHashMap;

/**
* 客户端对象，持有该对象可以随时向服务端发送消息
*
* @author admin
*
*/
public class Client {

/*
* 处理服务端发回的对象，可实现该接口
*/
public static interface ObjectAction {
void doAciton(Object object, Client client);
}

public static final class DefaultObjectAction
implements ObjectAction {

@Override
public void doAciton(Object object, Client client) {
System.out.println("处理：\t" + object.toString());
}
}

public static void main(String[] args) throws UnknownHostException, IOException {
String serverIp = "127.0.0.1";
int port = 65432;
Client client = new Client(serverIp, port);
client.start();
}

private final String serverIp;

private final int port;

private Socket socket;

private boolean running = false;

private long lastSendTime;

private final ConcurrentHashMap<Class, ObjectAction> actionMapping =
new ConcurrentHashMap<Class, ObjectAction>();

public Client(String serverIp, int port) {
this.serverIp = serverIp;
this.port = port;
}

public void start() throws UnknownHostException, IOException {
if (running)
return;
socket = new Socket(serverIp, port);
System.out.println("本地端口：" + socket.getLocalPort());
lastSendTime = System.currentTimeMillis();
running = true;
new Thread(new KeepAliveWatchDog()).start();
new Thread(new ReceiveWatchDog()).start();
}

public void stop() {
if (running)
running = false;
}

/**
* 添加接收对象的处理对象。
*
* @param cls
*        待处理的对象，其所属的类。
* @param action
*        处理过程对象。
*/
public void addActionMap(Class<Object> cls, ObjectAction action) {
actionMapping.put(cls, action);
}

public void sendObject(Object obj) throws IOException {
ObjectOutputStream oos =
new ObjectOutputStream(socket.getOutputStream());
oos.writeObject(obj);
System.out.println("发送：\t" + obj);
oos.flush();
}

class KeepAliveWatchDog
implements Runnable {
long checkDelay = 10;
long keepAliveDelay = 2000;
@Override
public void run() {
while (running) {
if (System.currentTimeMillis()
- lastSendTime > keepAliveDelay) {
try {
Client.this.sendObject(new KeepAlive());
}
catch (IOException e) {
e.printStackTrace();
Client.this.stop();
}
lastSendTime = System.currentTimeMillis();
}
else {
try {
Thread.sleep(checkDelay);
}
catch (InterruptedException e) {
e.printStackTrace();
Client.this.stop();
}
}
}
}
}

class ReceiveWatchDog
implements Runnable {
@Override
public void run() {
while (running) {
try {
InputStream in = socket.getInputStream();
if (in.available() > 0) {
ObjectInputStream ois = new ObjectInputStream(in);
Object obj = ois.readObject();
System.out.println("接收：\t" + obj);
ObjectAction oa = actionMapping.get(obj.getClass());
oa = oa == null ? new DefaultObjectAction() : oa;
oa.doAciton(obj, Client.this);
}
else {
Thread.sleep(10);
}
}
catch (Exception e) {
e.printStackTrace();
Client.this.stop();
}
}
}
}
}

server：

java代码

package socketConnection;

import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.ConcurrentHashMap;

public class Server {
/**
* 要处理客户端发来的对象，并返回一个对象，可实现该接口。
*/
public interface ObjectAction {
Object doAction(Object rev);
}

public static final class DefaultObjectAction
implements ObjectAction {
@Override
public Object doAction(Object rev) {
System.out.println("处理并返回：" + rev);
return rev;
}
}

public static void main(String[] args) {
int port = 65432;
Server server = new Server(port);
server.start();
}

private final int port;

private volatile boolean running = false;

private final long receiveTimeDelay = 3000;

private final ConcurrentHashMap<Class, ObjectAction> actionMapping =
new ConcurrentHashMap<Class, ObjectAction>();

private Thread connWatchDog;

public Server(int port) {
this.port = port;
}

public void start() {
if (running)
return;
running = true;
connWatchDog = new Thread(new ConnWatchDog());
connWatchDog.start();
}

@SuppressWarnings("deprecation")
public void stop() {
if (running)
running = false;
if (connWatchDog != null)
connWatchDog.stop();
}

public void addActionMap(Class<Object> cls, ObjectAction action) {
actionMapping.put(cls, action);
}

class ConnWatchDog
implements Runnable {
@Override
public void run() {
try {
ServerSocket ss = new ServerSocket(port, 5);
while (running) {
Socket s = ss.accept();
new Thread(new SocketAction(s)).start();
}
}
catch (IOException e) {
e.printStackTrace();
Server.this.stop();
}

}
}

class SocketAction
implements Runnable {
Socket s;

boolean run = true;

long lastReceiveTime = System.currentTimeMillis();

public SocketAction(Socket s) {
this.s = s;
}

@Override
public void run() {
while (running && run) {
if (System.currentTimeMillis()
- lastReceiveTime > receiveTimeDelay) {
overThis();
}
else {
try {
InputStream in = s.getInputStream();
if (in.available() > 0) {
ObjectInputStream ois = new ObjectInputStream(in);
Object obj = ois.readObject();
lastReceiveTime = System.currentTimeMillis();
System.out.println("接收：\t" + obj);
ObjectAction oa = actionMapping.get(obj.getClass());
oa = oa == null ? new DefaultObjectAction() : oa;
Object out = oa.doAction(obj);
if (out != null) {
ObjectOutputStream oos = new ObjectOutputStream(
s.getOutputStream());
oos.writeObject(out);
oos.flush();
}
}
else {
Thread.sleep(10);
}
}
catch (Exception e) {
e.printStackTrace();
overThis();
}
}
}
}

private void overThis() {
if (run)
run = false;
if (s != null) {
try {
s.close();
}
catch (IOException e) {
e.printStackTrace();
}
}
System.out.println("关闭：" + s.getRemoteSocketAddress());
}

}
}