java 服务端怎么释放http连接

通过轮询来实现长连接

轮询：隔一段时间访问服务器，服务器不管有没有新消息都立刻返回。

http长连接实现代码：

客户端：

package houlei.csdn.keepalive;

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;

/**

* 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。

* <p>

* 创建时间：2010-7-18 上午12:17:25

* @author HouLei

* @since 1.0

*/

public class Client {

/**

* 处理服务端发回的对象，可实现该接口。

*/

public static interface ObjectAction{

void doAction(Object obj,Client client);

}

public static final class DefaultObjectAction implements ObjectAction{

public void doAction(Object obj,Client client) {

System.out.println(处理：\t+obj.toString());//诊断程序是否正常

}

}

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 String serverIp;

private int port;

private Socket socket;

private boolean running=false;

private long lastSendTime;

private 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;

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{

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);//接受数据

ObjectAction oa = actionMapping.get(obj.getClass());

oa = oa==null?new DefaultObjectAction():oa;

oa.doAction(obj, Client.this);

}else{

Thread.sleep(10);

}

} catch (Exception e) {

e.printStackTrace();

Client.this.stop();

}

}

}

}

}

服务端：

package houlei.csdn.keepalive;

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;

/**

* C/S架构的服务端对象。

* <p>

* 创建时间：2010-7-18 上午12:17:37

* @author HouLei

* @since 1.0

*/

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{

public Object doAction(Object rev) {

System.out.println(处理并返回：+rev);//确认长连接状况

return rev;

}

}

public static void main(String[] args) {

int port = 65432;

Server server = new Server(port);

server.start();

}

private int port;

private volatile boolean running=false;

private long receiveTimeDelay=3000;

private 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{

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;

}

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());//关闭长连接

}

}

}

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。