場景
websocket是Html5新增加特性之一，目的是瀏覽器與服務端建立全雙工的通信方式，解決http請求-響應帶來過多的資源消耗，同時對特殊場景應用提供了全新的實現方式，例如聊天、股票交易、遊戲等對對即時性要求較高的產業領域。
背景
在瀏覽器中透過http僅能實現單向的通訊,comet可以一定程度上模擬雙向通訊,但效率較低,並需要伺服器有較好的支援; flash中的socket和xmlsocket可以實現真正的雙向通信,通過flex ajax bridge,可以在javascript中使用這兩項功能. 可以預見,如果websocket一旦在瀏覽器中得到實現,將會替代上面兩項技術,得到廣泛的使用.面對這種狀況，HTML5定義了WebSocket協議，能更好的節省伺服器資源和頻寬並達到即時通訊。目前各大主流瀏覽器都支援websocket，IE瀏覽器要IE10+
一、POM依賴
POM依賴，spring4.1.4.RELEASE，spring
<dependency>
<groupId>javax.websocket</groupId>
<artifactId>javax.websocket-api</artifactId>
<version>1.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-websocket</artifactId>
<version>4.1.4.RELEASE</version>
</dependency>
登入後複製
二、WebSocket入口
@Configuration
@EnableWebMvc
@EnableWebSocket
public class WebSocketConfig extends WebMvcConfigurerAdapter implements WebSocketConfigurer {
@Override
public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
//允许连接的域,只能以http或https开头
String[] allowsOrigins = {"http://www.xxx.com"};
//WebIM WebSocket通道
registry.addHandler(chatWebSocketHandler(),"/ webSocketIMServer").setAllowedOrigins(allowsOrigins).addInterceptors(myInterceptor());
registry.addHandler(chatWebSocketHandler(), "/sockjs/w ebSocketIMServer").setAllowedOrigins(allowsOrigins).addInterceptors(myInterceptor()).withSockJS();
}
@Bean
public ChatWebSocketHandler chatWebSocketHandler() {
return new ChatWebSocketHandler();
}
@Bean
public WebSocketHandshakeInterceptor myInterceptor(){
return new WebSocketHandshakeInterceptor();
}
}登入後複製
實現WebSocketConfigurer接口，重寫registerWebSocketHandlers方法，這是一個核心實現方法，配置websocket入口，允許訪問的域、Handler、SockJs支援和攔截器。
public class WebSocketHandshakeInterceptor implements HandshakeInterceptor {
@Override
public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Map<String, Object
> attributes) throws Exception {
if (request instanceof ServletServerHttpRequest) {
attributes.put("username",userName);
}
return true;
}
@Override
public void afterHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Exception exception) {
}
}登入後複製
beforeHandshake，在呼叫handler前處理方法。常用在註冊用戶訊息，綁定WebSocketSession，在handler裡根據用戶資訊取得WebSocketSession
發送訊息
。 四、Handler處理類
public class ChatWebSocketHandler extends TextWebSocketHandler{
private final static List<WebSocketSession> sessions = Collections.synchronizedList(new ArrayList<WebSocketSession>());
//接收文本消息，并发送出去
@Override
protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
chatTextMessageHandler(message.getPayload());
super.handleTextMessage(session, message);
}
//连接建立后处理
@SuppressWarnings("unchecked")
@Override
public void afterConnectionEstablished(WebSocketSession session) throws Exception {
logger.debug("connect to the websocket chat success......");
sessions.add(session);
//处理离线消息
}
//抛出异常时处理
@Override
public void handleTransportError(WebSocketSession session, Throwable exception) throws Exception {
if(session.isOpen()){
session.close();
}
logger.debug("websocket chat connection closed......");
sessions.remove(session);
}
//连接关闭后处理
@Override
public void afterConnectionClosed(WebSocketSession session, CloseStatus closeStatus) throws Exception {
logger.debug("websocket chat connection closed......");
sessions.remove(session);
}
@Override
public boolean supportsPartialMessages() {
return false;
}
}登入後複製
五、客戶端連接
var host = window.location.host;
var websocket;
if ('WebSocket' in window) {
websocket = new ReconnectingWebSocket("ws://"
+ host + "/webSocketIMServer", null, {debug:true, maxReconnectAttempts:4});
} else if ('MozWebSocket' in window) {
websocket = new MozWebSocket("ws://" + host
+ "/webSocketIMServer");
} else {
websocket = new SockJS("http://" + host
+ "/sockjs/webSocketIMServer");
}
websocket.onopen = function(evnt) {
console.log("websocket连接上");
};
websocket.onmessage = function(evnt) {
messageHandler(evnt.data);
};
websocket.onerror = function(evnt) {
console.log("websocket错误");
};
websocket.onclose = function(evnt) {
console.log("websocket关闭");
}登入後複製
這裡用到了ReconnectingWebSocket.js,對瀏覽器自帶websocket添加了擴展，例如重連，連接超時時間，失敗重連間隔，嘗試連接最大次數等。
專案首頁:ReconnectingWebSocket
以上是spring WebSocket的詳細介紹的詳細內容。更多資訊請關注PHP中文網其他相關文章！
