jee websocket搭建总结
1、使用框架spring+springmvc+mybatis+jdk7+tomcat7+maven
2、基本原理：
a. WebSocket协议是一种双向通信协议，它建立在TCP之上，同http一样通过TCP来传输数据，但是 它和http最大的不同有两点：
1.WebSocket是一种双向通信协议，在建立连接后，WebSocket服务器和Browser/UA都能主动地向对方发送或接收数据，就像Socket一样，不同的是WebSocket是一种建立在Web基础上的一种简单模拟Socket的协议；
2.WebSocket需要通过握手连接，类似于TCP它也需要客户端和服务器端进行握手连接，连接成功后才能相互通信。
b.struts 和 websocket 是2条处理请求的路，被struts 匹配上了 ，自然就到不了 websocket的处 理逻辑,(http和ws是两种不同的请求协议，注意框架的拦截器（过滤器）)
3、客户端：
<html> <head> <title>Title</title> <style> div { margin-left: auto; margin-right: auto; } </style> </head> <body onLoad="startWebSocket()"> <script type="text/javascript"> function clog(title) { console.log(title); } var ws = null; function startWebSocket() { if ('WebSocket' in window) { try { ws = new WebSocket("ws://127.0.0.1:80/websocket/tui"); } catch (e) { clog("1"); } } else if ('MozWebSocket' in window) { ws = new MozWebSocket("ws://127.0.0.1:80/websocket/tui"); } else { clog("websocket not support"); } ws.onmessage = function (evt) { say(evt.data); }; ws.onclose = function (evt) { clog("close!"); }; ws.onopen = function (evt) { clog("open"); }; } function sendMsg() { ws.send(document.getElementById('writeMsg').value); } function say(msg) { var div = document.createElement("div"); div.innerHTML = msg; document.body.appendChild(div); } </script> <div onClick="say('d')">WebSocket聊天室</div> <div style="border:1px solid #09F"></div> <input type="text" id="writeMsg"/> <input type="button" value="send" onClick="sendMsg()"/> </body> </html>
4、服务端：
@ServerEndpoint(value = "/websocket/tui") public class WebSocketDemo{ private static final String GUEST_PREFIX = "Guest"; private static final AtomicInteger connectionIds = new AtomicInteger(0); private static final Set<WebSocketDemo> connections = new HashSet<>(); private final String nickname; private Session session; public WebSocketDemo() { nickname = GUEST_PREFIX + connectionIds.getAndIncrement(); } //建立连接 @OnOpen public void start(Session session) { this.session = session; connections.add(this); String message = String.format("* %s %s", nickname, "has joined."); System.out.println(message); } //接受消息 @OnMessage public void incoming(String message) { System.out.println(message.toString()); //broadcast(filteredMessage); broadcast(message.toString()); } //客户端关闭了连接 @OnClose public void end() { connections.remove(this); String message = String.format("* %s %s", nickname, "has disconnected."); System.out.println(message); //broadcast(message); } //WebSocket服务出错 @OnError public void onError(Throwable t){ //log.error("Chat Error: " + t.toString(), t); System.out.println("server has an error!"); } private static void broadcast(String msg) { for (WebSocketDemo client : connections) { try { synchronized (client) { client.session.getBasicRemote().sendText(msg); } } catch (IOException e) { //log.debug("Chat Error: Failed to send message to client", e); connections.remove(client); try { client.session.close(); } catch (IOException e1) { // Ignore } String message = String.format("* %s %s", client.nickname, "has been disconnected."); broadcast(message); } } } }
注意事项：
1、访问拦截器
2、注意部署的包冲突，例如：javax.websocket只是编译需要，而发布不需要，maven依赖注意适用范围
附：
<!--websocket编译需要，发布不需要--> <!-- https://mvnrepository.com/artifact/org.apache.tomcat/tomcat-coyote --> <dependency> <groupId>org.apache.tomcat</groupId> <artifactId>tomcat-coyote</artifactId> <version>7.0.12</version> </dependency> <!-- https://mvnrepository.com/artifact/org.apache.tomcat/tomcat-juli --> <dependency> <groupId>org.apache.tomcat</groupId> <artifactId>tomcat-juli</artifactId> <version>8.5.3</version> </dependency> <!-- https://mvnrepository.com/artifact/javax.websocket/javax.websocket-api --> <dependency> <groupId>javax.websocket</groupId> <artifactId>javax.websocket-api</artifactId> <version>1.1</version> <scope>provided</scope> </dependency>
