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Java Websocket实例【服务端与客户端实现全双工通讯】

發(fā)布時間：2023/11/27 生活经验 36 豆豆

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Java Websocket實(shí)例【服務(wù)端與客戶端實(shí)現(xiàn)全雙工通訊】

現(xiàn)很多網(wǎng)站為了實(shí)現(xiàn)即時通訊，所用的技術(shù)都是輪詢(polling)。輪詢是在特定的的時間間隔（如每1秒），由瀏覽器對服務(wù)器發(fā)

出HTTP?request，然后由服務(wù)器返回最新的數(shù)據(jù)給客服端的瀏覽器。這種傳統(tǒng)的HTTP?request?的模式帶來很明顯的缺點(diǎn)?–?瀏

覽器需要不斷的向服務(wù)器發(fā)出請求，然而HTTP?request?的header是非常長的，里面包含的數(shù)據(jù)可能只是一個很小的值，這樣會占

用很多的帶寬。WebSocket提供了一個受歡迎的技術(shù)，以替代我們過去幾年一直在用的Ajax技術(shù)。

一、什么是WebSocket?API?

WebSocket?API是下一代客戶端-服務(wù)器的異步通信方法。該通信取代了單個的TCP套接字，使用ws或wss協(xié)議，可用于任意的

客戶端和服務(wù)器程序。WebSocket目前由W3C進(jìn)行標(biāo)準(zhǔn)化。WebSocket已經(jīng)受到Firefox?4、Chrome?4、Opera?10.70以及Safari?5等

瀏覽器的支持。

WebSocket?API最偉大之處在于服務(wù)器和客戶端可以在給定的時間范圍內(nèi)的任意時刻，相互推送信息。WebSocket并不限于以

Ajax(或XHR)方式通信，因?yàn)?/span>Ajax技術(shù)需要客戶端發(fā)起請求，而WebSocket服務(wù)器和客戶端可以彼此相互推送信息；XHR受到域

的限制，而WebSocket允許跨域通信。

Ajax技術(shù)很聰明的一點(diǎn)是沒有設(shè)計(jì)要使用的方式。WebSocket為指定目標(biāo)創(chuàng)建，用于雙向推送消息。

那么我就開始我在項(xiàng)目中對websocket的使用，首先使用的是J2EE7的架包。

架包加完之后，只需要再添加2個類就可以實(shí)現(xiàn)使用的功能了。

首先添加一個Java類，WebsocketController.java

[java]?view plaincopy

package?com.lwl.activemq.controller.websocket;??
??
import?java.util.Map;??
import?java.util.concurrent.ConcurrentHashMap;??
??
import?javax.websocket.*;??
import?javax.websocket.server.PathParam;??
import?javax.websocket.server.ServerEndpoint;??
??
??
import?org.slf4j.Logger;??
import?org.slf4j.LoggerFactory;??
/**?
?*?功能說明：websocket處理類,?使用J2EE7的標(biāo)準(zhǔn)?
?*?@author?Administrator?
?*?@create?2016-8-11?下午4:08:35?
?*?@version?1.0?
?*/??
@ServerEndpoint("/websocket/{myWebsocket}")??
public?class?WebsocketController?{??
????private?static?final?Logger?logger?=?LoggerFactory.getLogger(WebsocketController.class);??
??
????public?static?Map<String,?Session>?clients?=?new?ConcurrentHashMap<String,?Session>();??
??
????/**?
?????*?打開連接時觸發(fā)?
?????*?@param?myWebsocket?
?????*?@param?session?
?????*/??
????@OnOpen??
????public?void?onOpen(@PathParam("myWebsocket")?String?myWebsocket,?Session?session){??
????????logger.info("Websocket?Start?Connecting:"?+?myWebsocket);??
????????System.out.println("進(jìn)入："+myWebsocket);??
????????clients.put(myWebsocket,?session);??
????}??
??
????/**?
?????*?收到客戶端消息時觸發(fā)?
?????*?@param?myWebsocket?
?????*?@param?message?
?????*?@return?
?????*/??
????@OnMessage??
????public?String?onMessage(@PathParam("myWebsocket")?String?myWebsocket,?String?message)?{??
????????return?"Got?your?message?("+?message?+").Thanks?!";??
????}??
??
????/**?
?????*?異常時觸發(fā)?
?????*?@param?myWebsocket?
?????*?@param?throwable?
?????*/??
????@OnError??
????public?void?onError(@PathParam("myWebsocket")?String?myWebsocket,?Throwable?throwable)?{??
????????logger.info("Websocket?Connection?Exception:"?+?myWebsocket);??
????????logger.info(throwable.getMessage(),?throwable);??
????????clients.remove(myWebsocket);??
????}??
??
????/**?
?????*?關(guān)閉連接時觸發(fā)?
?????*?@param?myWebsocket?
?????*/??
????@OnClose??
????public?void?onClose(@PathParam("myWebsocket")?String?myWebsocket)?{??
????????logger.info("Websocket?Close?Connection:"?+?myWebsocket);??
????????clients.remove(myWebsocket);??
????}??
??
??
????/**?
?????*?將數(shù)據(jù)傳回客戶端?
?????*?異步的方式?
?????*?@param?myWebsocket?
?????*?@param?message?
?????*/??
????public?static?void?broadcast(String?myWebsocket,?String?message)?{??
????????if?(clients.containsKey(myWebsocket))?{??
????????????clients.get(myWebsocket).getAsyncRemote().sendText(message);??
????????}?else?{??
????????????throw?new?NullPointerException("["?+?myWebsocket?+"]Connection?does?not?exist");??
????????}??
????}??
??
}??

然后添加相應(yīng)的接受頁面index.html：

[html]?view plaincopy

<!DOCTYPE?HTML?PUBLIC?"-//W3C//DTD?HTML?4.01?Transitional//EN"?"http://www.w3.org/TR/html4/loose.dtd">??
<html>??
????<head>??
????????<meta?http-equiv="Content-Type"?content="text/html;?charset=UTF-8">??
????????<meta?http-equiv="X-UA-Compatible"?content="IE=edge">??
????????<meta?name="viewport"?content="width=device-width,?initial-scale=1">??
??????????<script?type="text/javascript"?src="resources/jquery-1.8.3.min.js"></script>??
?????</head>?????
<body>??
??
???
<script?type="text/javascript">??
?//測試controller是否可以進(jìn)入??
//?ajaxDo("/activemq-client/index",null);??
???
//?function?ajaxDo(url,data){??
//???$.ajax({??
//??????????url:url?,??
//??????????type:?"post",??
//??????????dataType:?"json",??
//??????????data:?data,??
//??????????success:function(result){??
//?????????????if(result.success){??
//?????????????????alert(result.data);??
//?????????????}else{??
//?????????????????alert(result.msg);??
//?????????????}??
//??????????}??
//??????});??
//?}??????
??
??
//---------------------------------?webSocket?----------------------------------------------??
??initSocket("user");??
??initSocket("news");??
??initSocket("client");??
????
??
function?initSocket(myWebsocket)?{??
??????
????var?webSocket?=?null;??
??????
????window.onbeforeunload?=?function?()?{??
????????//離開頁面時的其他操作??
????};??
??
????if?(!window.WebSocket)?{??
????????console("您的瀏覽器不支持websocket！");??
????????return?false;??
????}??
??
????var?target?=?'ws://'?+?window.location.host?+?"/activemq-client/websocket/"+myWebsocket;????
????????????
????????if?('WebSocket'?in?window)?{????
????????????webSocket?=?new?WebSocket(target);????
????????}?else?if?('MozWebSocket'?in?window)?{????
????????????webSocket?=?new?MozWebSocket(target);????
????????}?else?{????
????????????alert('WebSocket?is?not?supported?by?this?browser.');????
????????????return;????
????????}????
??????
??????
????//?收到服務(wù)端消息??
????webSocket.onmessage?=?function?(msg)?{??
????????????alert(msg.data);??
????????//?關(guān)閉連接??
????????webSocket.onclose();??
????????console.log(msg);??
????};??
??
????//?異常??
????webSocket.onerror?=?function?(event)?{??
????????console.log(event);??
????};??
??
????//?建立連接??
????webSocket.onopen?=?function?(event)?{??
????????console.log(event);??
????};??
??
????//?斷線??
????webSocket.onclose?=?function?()?{??
??????????
????????console.log("websocket斷開連接");??
????};??
}??
??
??
</script>??
??
</body>??
</html>??

好了，websocket已經(jīng)實(shí)現(xiàn)了，現(xiàn)在最重要的是我們要在哪兒監(jiān)聽哪些變動，在推送給前端的問題了，這里我監(jiān)聽了MQ消息隊(duì)

列中的某個Queen，如果獲取到消息就推送給前端展示，稍后我會把MQ的消息隊(duì)列也寫給大家看，做個參考。（當(dāng)然你也可以

監(jiān)聽屬于你自己的對象，主要是調(diào)用?WebsocketController.broadcast("client", jsonStr);第一個參數(shù)和前端的參數(shù)一

致，第二個參數(shù)是你想推送給前端的內(nèi)容）。

[java]?view plaincopy

<span?style="font-size:14px;"><span?style="font-family:宋體;">package?com.lwl.activemq.listener;??
??
import?javax.jms.JMSException;??
import?javax.jms.Message;??
import?javax.jms.MessageListener;??
import?javax.jms.TextMessage;??
??
import?org.apache.log4j.Logger;??
import?org.springframework.stereotype.Component;??
??
import?com.alibaba.fastjson.JSON;??
import?com.lwl.activemq.domain.Client;??
import?com.lwl.activemq.controller.websocket.WebsocketController;??
??
@Component("clientPushListener")??
public?class?ClientPushListener?implements?MessageListener?{??
?????protected?static?final?Logger?logger?=?Logger.getLogger(ClientPushListener.class);??
????@Override??
????public?void?onMessage(Message?message)?{??
?????????logger.info("[ClientPushListener.onMessage]:begin?onMessage.");??
????????????TextMessage?textMessage?=?(TextMessage)?message;??
????????????try?{??
????????????????String?jsonStr?=?textMessage.getText();??
????????????????logger.info("[ClientPushListener.onMessage]:receive?message?is,"+?jsonStr);??
????????????????if?(jsonStr?!=?null)?{??
????????????????????Client?info?=?JSON.parseObject(jsonStr,?Client.class);??
????????????????????System.out.println("==============================接受到的客戶信息?開始====================================");??
????????????????????System.out.println(info.toString());??
????????????????????System.out.println("==============================接受到的客戶信息?結(jié)束====================================");??
????????????????????WebsocketController.broadcast("client",?jsonStr);??
????????????????}??
????????????}?catch?(JMSException?e)?{??
????????????????logger.error("[ClientPushListener.onMessage]:receive?message?occured?an?exception",e);??
????????????}??
????????????logger.info("[ClientPushListener.onMessage]:end?onMessage.");??
????????}??
}</span></span>??

轉(zhuǎn)自： http://blog.csdn.net/LOVELONG8808/article/details/52277029

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