WebSocket實現Android消息推送

前段時間做一個項目，需要Android客戶端作為管理工具與web服務器後台實時交互，想了很多方法，包括androidpn、openfire+smack、xmpp協議，要麼太繁瑣，要麼無法滿足實時性。想來還是用socket，經人提醒想到了websocket。

websocket協議是近些年隨html5發展而誕生的，主要用於解決web服務器與客戶端無法雙向交互的問題。如今已經被W3C收入標准協議。

服務器支持：tomcat、jetty的最新版本都已支持websocket；如果不想更換現有服務器，也可用spring4.0作為替代。據說新版本的jre將收入websocket類，沒具體接觸。

客戶端支持：目前的主流浏覽器都已經實現了websocket，但由於前期協議版本變化太快，很多廠商沒有跟上。android默認浏覽器就不支持websocket，IE也直到IE10才支持。

網上已有通過html實現websocket client的例子，這裡我們用java實現客戶端連接。廢話不說，上Demo：

1.服務器端

服務器用了tomcat 7.0，直接使用tomcat的websocket實現

1）連接管理類

import java.io.IOException;
import java.nio.CharBuffer;
import java.util.ArrayList;
import java.util.List;
import org.apache.catalina.websocket.MessageInbound;
import org.apache.catalina.websocket.WsOutbound;

public class MessageCenter
{
private static MessageCenter instance = new MessageCenter();

private List<MessageInbound> socketList;

private MessageCenter()
{
this.socketList = new ArrayList<MessageInbound>();
}

public static MessageCenter getInstance()
{
return instance;
}

public void addMessageInbound(MessageInbound inbound)
{
socketList.add(inbound);
}

public void removeMessageInbound(MessageInbound inbound)
{
socketList.remove(inbound);
}

public void broadcast(CharBuffer msg) throws IOException
{
for (MessageInbound messageInbound : socketList)
{
CharBuffer buffer = CharBuffer.wrap(msg);
WsOutbound outbound = messageInbound.getWsOutbound();
outbound.writeTextMessage(CharBuffer.wrap("broadcasting:" + msg));
// outbound.writeTextMessage(buffer);
outbound.flush();
}
}
}

2）消息入口類

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.util.Date;

import org.apache.catalina.websocket.MessageInbound;
import org.apache.catalina.websocket.WsOutbound;

public class MyMessageInbound extends MessageInbound {

@Override
protected void onBinaryMessage(ByteBuffer arg0) throws IOException {
// TODO Auto-generated method stub

}

@Override
protected void onTextMessage(CharBuffer msg) throws IOException {
System.out.println("Received:"+msg);
MessageCenter.getInstance().broadcast(msg);

}

@Override
protected void onClose(int status) {
System.out.println("close:"+new Date());
MessageCenter.getInstance().removeMessageInbound(this);
super.onClose(status);
}

@Override
protected void onOpen(WsOutbound outbound) {
System.out.println("open :"+new Date());
super.onOpen(outbound);
MessageCenter.getInstance().addMessageInbound(this);
}
}

3）Websocket servlet

import javax.servlet.http.HttpServletRequest;

import org.apache.catalina.websocket.StreamInbound;
import org.apache.catalina.websocket.WebSocketServlet;

public class MeWebSocketServlet extends WebSocketServlet
{

private static final long serialVersionUID = -7178893327801338294L;

@Override
protected StreamInbound createWebSocketInbound(String subProtocol, HttpServletRequest request)
{
System.out.println("##########client login#########");
return new MeMessageInbound();
}

}

4）添加servlet到web.xml

< servlet>
< servlet-name> android</ servlet-name >
< servlet-class> MyWebSocketServlet </servlet-class >
</ servlet>
< servlet-mapping>
< servlet-name> android</ servlet-name >
< url-pattern> *.do</ url-pattern >
</ servlet-mapping>

更多詳情見請繼續閱讀下一頁的精彩內容： http://www.linuxidc.com/Linux/2013-11/92474p2.htm