Spring4.0系列9-websocket简单应用

import org.springframework.web.socket.server.endpoint.ServerEndpointExporter;
import org.springframework.web.socket.server.endpoint.ServerEndpointRegistration;
@Configuration
public class EndpointConfig {
@Bean
public EndpointRegistration echoEndpoint() {
return new EndpointRegistration("/echo", EchoEndpoint.class);
}
@Bean
public ServerEndpointExporter endpointExporter() {
return new ServerEndpointExporter();
}
// ..
}

2、Spring WebSocket API

Spring WebSocket API提供了SockJS的支持，且有些容器如Jetty 9目前还没有对JSR-356的支持，所以有Spring WebSocket API是必要的。

Spring WebSocket API的核心接口是WebSocketHandler。下面是一个处理文本消息的handler的实现：

Java代码

import org.springframework.web.socket.adapter.TextWebSocketHandlerAdapter;
public class EchoHandler extends TextWebSocketHandlerAdapter {
@Override
public void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
session.sendMessage(message);
}
}

WebSocketHandler可以通过WebSocketHttpRequestHandler插入到Spring MVC里：

Java代码

import org.springframework.web.socket.server.support.WebSocketHttpRequestHandler;
@Configuration
public class WebConfig {
@Bean
public SimpleUrlHandlerMapping handlerMapping() {
Map<String, Object> urlMap = new HashMap<String, Object>();
urlMap.put("/echo", new WebSocketHttpRequestHandler(new EchoHandler()));
SimpleUrlHandlerMapping hm = new SimpleUrlHandlerMapping();
hm.setUrlMap(urlMap);
return hm;
}
}

SockJs是一个脚本框架，它提供类似于websocket的编程模式但是可以适应不同的浏览器（包括不支持websocket的浏览器）。

开启SockJS的支持，声明一个SockJsService，和一个url映射，然后提供一个WebSocketHandler来处理消息。虽然我们是哟个SockJS我们开发的方式是一样的，但是随着浏览器的不同传输的协议可以是Http Streaming，long polling等。

Java代码

import org.springframework.web.socket.sockjs.SockJsService;
// ...
@Configuration
public class WebConfig {
@Bean
public SimpleUrlHandlerMapping handlerMapping() {
SockJsService sockJsService = new DefaultSockJsService(taskScheduler());
Map<String, Object> urlMap = new HashMap<String, Object>();
urlMap.put("/echo/**", new SockJsHttpRequestHandler(sockJsService, new EchoHandler()));
SimpleUrlHandlerMapping hm = new SimpleUrlHandlerMapping();
hm.setUrlMap(urlMap);
return hm;
}
@Bean
public ThreadPoolTaskScheduler taskScheduler() {
ThreadPoolTaskScheduler taskScheduler = new ThreadPoolTaskScheduler();
taskScheduler.setThreadNamePrefix("SockJS-");
return taskScheduler;
}
}

在我们实际使用中我们会使用WebSocketConfigurer集中注册WebSocket服务：

Java代码

@Configuration
@EnableWebMvc
@EnableWebSocket//开启websocket
public class WebConfig extends WebMvcConfigurerAdapter implements WebSocketConfigurer {
@Override
public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
registry.addHandler(echoWebSocketHandler(), "/echo"); //提供符合W3C标准的Websocket数据
registry.addHandler(snakeWebSocketHandler(), "/snake");
registry.addHandler(echoWebSocketHandler(), "/sockjs/echo").withSockJS();//提供符合SockJS的数据
registry.addHandler(snakeWebSocketHandler(), "/sockjs/snake").withSockJS();
}
@Bean
public WebSocketHandler echoWebSocketHandler() {
return new EchoWebSocketHandler(echoService());
}
@Bean
public WebSocketHandler snakeWebSocketHandler() {
return new PerConnectionWebSocketHandler(SnakeWebSocketHandler.class);
}
@Bean
public DefaultEchoService echoService() {
return new DefaultEchoService("Did you say \"%s\"?");
}
// Allow serving HTML files through the default Servlet
@Override
public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
configurer.enable();
}
}

Java代码

ws = new SockJS(url, undefined, {protocols_whitelist: transports}) ； //初始化 websocket
ws.onopen = function () {
setConnected(true);
log(‘Info: connection opened.‘);
};
ws.onmessage = function (event) {
log(‘Received: ‘ + event.data); //处理服务端返回消息
};
ws.onclose = function (event) {
setConnected(false);
log(‘Info: connection closed.‘);
log(event);
};
ws.send(message);//向服务端发送消息