您好,登錄后才能下訂單哦!
JAVA中怎么實現(xiàn)長連接,相信很多沒有經(jīng)驗的人對此束手無策,為此本文總結了問題出現(xiàn)的原因和解決方法,通過這篇文章希望你能解決這個問題。
實現(xiàn)原理: 長連接的維持,是要客戶端程序,定時向服務端程序,發(fā)送一個維持連接包的。 如果,長時間未發(fā)送維持連接包,服務端程序將斷開連接。
客戶端: Client通過持有Socket的對象,可以隨時(使用sendObject方法)發(fā)送Massage Object(消息)給服務端。 如果keepAliveDelay毫秒(程序中是2秒)內未發(fā)送任何數(shù)據(jù),則自動發(fā)送一個KeepAlive Object(心跳)給服務端,用于維持連接。 由于,我們向服務端,可以發(fā)送很多不同的消息對象,服務端也可以返回不同的對象。所以,對于返回對象的處理,要編寫具體的ObjectAction實現(xiàn)類進行處理。通過Client.addActionMap方法進行添加。這樣,程序會回調處理。
服務端: 由于客戶端會定時(keepAliveDelay毫秒)發(fā)送維持連接的信息過來,所以,服務端要有一個檢測機制。 即當服務端receiveTimeDelay毫秒(程序中是3秒)內未接收任何數(shù)據(jù),則自動斷開與客戶端的連接。 ActionMapping的原理與客戶端相似(相同)。
通過添加相應的ObjectAction實現(xiàn)類,可以實現(xiàn)不同對象的響應、應答過程。
Demo:
package socket.keepalive.test; import java.io.Serializable;import java.text.SimpleDateFormat;import java.util.Date; /** * * 維持連接的消息對象(心跳對象) */public class KeepAlive implements Serializable{ private static final long serialVersionUID = -2813120366138988480L; /* 覆蓋該方法,僅用于測試使用。 * @see java.lang.Object#toString() */ @Override public String toString() { return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date())+"\t維持連接包"; } }
package socket.keepalive.test; 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.Collections;import java.util.concurrent.ConcurrentHashMap; /** * C/S架構的客戶端對象,持有該對象,可以隨時向服務端發(fā)送消息。 * <p> * 創(chuàng)建時間:2010-7-18 上午12:17:25 * @author HouLei * @since 1.0 */public class Client { /** * 處理服務端發(fā)回的對象,可實現(xiàn)該接口。 */ 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("處理:\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; //連接狀態(tài) private long lastSendTime; //最后一次發(fā)送數(shù)據(jù)的時間 //用于保存接收消息對象類型及該類型消息處理的對象 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(); //保持長連接的線程,每隔2秒項服務器發(fā)一個一個保持連接的心跳消息 new Thread(new ReceiveWatchDog()).start(); //接受消息的線程,處理消息 } public void stop(){ if(running)running=false; } /** * 添加接收對象的處理對象。 * @param cls 待處理的對象,其所屬的類。 * @param action 處理過程對象。 */ 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("發(fā)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(); } } } } }
package socket.keepalive.test; 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架構的服務端對象。 * <p> * 創(chuàng)建時間:2010-7-18 上午12:17:37 * @author HouLei * @since 1.0 */public class Server { /** * 要處理客戶端發(fā)來的對象,并返回一個對象,可實現(xiàn)該接口。 */ public interface ObjectAction{ Object doAction(Object rev, Server server); } public static final class DefaultObjectAction implements ObjectAction{ public Object doAction(Object rev,Server server) { System.out.println("處理并返回:"+rev); 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,Server.this); 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("關閉:"+s.getRemoteSocketAddress()); } } }
看完上述內容,你們掌握JAVA中怎么實現(xiàn)長連接的方法了嗎?如果還想學到更多技能或想了解更多相關內容,歡迎關注億速云行業(yè)資訊頻道,感謝各位的閱讀!
免責聲明:本站發(fā)布的內容(圖片、視頻和文字)以原創(chuàng)、轉載和分享為主,文章觀點不代表本網(wǎng)站立場,如果涉及侵權請聯(lián)系站長郵箱:is@yisu.com進行舉報,并提供相關證據(jù),一經(jīng)查實,將立刻刪除涉嫌侵權內容。