- package houlei.csdn.keepalive;
-
- import java.io.Serializable;
- import java.text.SimpleDateFormat;
- import java.util.Date;
-
- public class KeepAlive implements Serializable{
-
- private static final long serialVersionUID = -2813120366138988480L;
-
-
- @Override
- public String toString() {
- return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date())+"\t维持连接包";
- }
-
- }
- 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;
-
- public class Client {
-
-
- 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());
- }
- }
- 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;
- }
-
-
- 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);
- 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();
- }
- }
- }
- }
-
- }
大致解释一下什么意思:
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。
祝好运~~