spring4.0之九:websocket简单应用

Spring 4.0的一个最大更新是增加了websocket的支持。websocket提供了一个在web应用中的高效、双向的通讯,需要考虑到客户端(浏览器)和服务器之间的高频和低延时消息交换。一般的应用场景有:在线交易、游戏、协作、数据可视化等。

使用websocket需要考虑的浏览器的支持(IE<10不支持),目前主流的浏览器都能很好的支持websocket。

websocket协议中有一些子协议,可以从更高的层次实现编程模型,就像我们使用HTTP而不是TCP一样。这些子协议有STOMP,WAMP等。

 

本教程只考虑websocket的简单实用,包含Spring对JSR-356的支持及Spring WebSocket API。

1、Java API for WebSocket(JSR-356)

Java API for WebSocket已经是Java EE 7的一部分。它定义了两类endpoit(都是EndPoint类的子类),使用注解标识@ClientEndpoint和@ServerEndpoint。

1.1 Servlet容器扫描初始化

通过Spring初始化一个endpoint,只需配置一个SpringConfigurator在类上的@ServerEndpoint注解上。

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package org.springframework.samples.websocket.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.samples.websocket.echo.DefaultEchoService;
import org.springframework.samples.websocket.echo.EchoEndpoint;
import org.springframework.samples.websocket.echo.EchoService;
import org.springframework.web.socket.server.standard.ServerEndpointExporter;
import org.springframework.web.socket.server.standard.ServerEndpointRegistration;

@Configuration
public class EndpointConfig {

    @Bean
    public ServerEndpointExporter endpointExporter() {
        return new ServerEndpointExporter();
    }

    @Bean
    public ServerEndpointRegistration echo() {
        return new ServerEndpointRegistration("/echo", EchoEndpoint.class);
    }

    @Bean
    public ServerEndpointRegistration echoSingleton() {
        return new ServerEndpointRegistration("/echoSingleton", new EchoEndpoint(echoService()));
    }

//    @Bean
//    public EchoAnnotatedEndpoint echoAnnotatedSingleton() {
//        return new EchoAnnotatedEndpoint(echoService());
//    }

    @Bean
    public EchoService echoService() {
        return new DefaultEchoService("Did you say \"%s\"?");
    }
}

 上例假设SpringContextLoaderListener用来加载配置,这是个典型的web应用。Servlet容器将通过扫描@ServerEndpoint和SpringConfigurator初始化一个新的websocket会话。

 1.2 Spring 初始化

如果你想使用一个单独的实例而不使用Servlet容器扫描,将EchoEndpoint类声明称一个bean,并增加一个ServerEndpointExporter的bean:

package org.springframework.samples.websocket.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.samples.websocket.echo.DefaultEchoService;
import org.springframework.samples.websocket.echo.EchoEndpoint;
import org.springframework.samples.websocket.echo.EchoService;
import org.springframework.web.socket.server.standard.ServerEndpointExporter;
import org.springframework.web.socket.server.standard.ServerEndpointRegistration;

@Configuration
public class EndpointConfig {

    @Bean
    public ServerEndpointExporter endpointExporter() {
        return new ServerEndpointExporter();
    }

    @Bean
    public ServerEndpointRegistration echo() {
        return new ServerEndpointRegistration("/echo", EchoEndpoint.class);
    }

    @Bean
    public ServerEndpointRegistration echoSingleton() {
        return new ServerEndpointRegistration("/echoSingleton", new EchoEndpoint(echoService()));
    }

//    @Bean
//    public EchoAnnotatedEndpoint echoAnnotatedSingleton() {
//        return new EchoAnnotatedEndpoint(echoService());
//    }

    @Bean
    public EchoService echoService() {
        return new DefaultEchoService("Did you say \"%s\"?");
    }
}

 EchoEndpoint 可以通过EndPointRegistration发布

 

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  收藏代码
  1. import org.springframework.web.socket.adapter.TextWebSocketHandlerAdapter;  
  2.   
  3.   
  4. public class EchoHandler extends TextWebSocketHandlerAdapter {  
  5.   
  6.   @Override  
  7.   public void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {  
  8.     session.sendMessage(message);  
  9.   }  
  10.   
  11. }  

 

WebSocketHandler可以通过WebSocketHttpRequestHandler插入到Spring MVC里:

Java代码  收藏代码
  1. import org.springframework.web.socket.server.support.WebSocketHttpRequestHandler;  
  2.   
  3.   
  4. @Configuration  
  5. public class WebConfig {  
  6.   
  7.   @Bean  
  8.   public SimpleUrlHandlerMapping handlerMapping() {  
  9.   
  10.     Map<String, Object> urlMap = new HashMap<String, Object>();  
  11.     urlMap.put("/echo", new WebSocketHttpRequestHandler(new EchoHandler()));  
  12.   
  13.     SimpleUrlHandlerMapping hm = new SimpleUrlHandlerMapping();  
  14.     hm.setUrlMap(urlMap);  
  15.     return hm;  
  16.   }  
  17.   
  18. }  

 SockJS服务器端的支持

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  收藏代码
  1. import org.springframework.web.socket.sockjs.SockJsService;  
  2. // ...  
  3.   
  4.   
  5. @Configuration  
  6. public class WebConfig {  
  7.   
  8.   @Bean  
  9.   public SimpleUrlHandlerMapping handlerMapping() {  
  10.   
  11.     SockJsService sockJsService = new DefaultSockJsService(taskScheduler());  
  12.   
  13.     Map<String, Object> urlMap = new HashMap<String, Object>();  
  14.     urlMap.put("/echo/**", new SockJsHttpRequestHandler(sockJsService, new EchoHandler()));  
  15.   
  16.     SimpleUrlHandlerMapping hm = new SimpleUrlHandlerMapping();  
  17.     hm.setUrlMap(urlMap);  
  18.     return hm;  
  19.   }  
  20.   
  21.   @Bean  
  22.   public ThreadPoolTaskScheduler taskScheduler() {  
  23.     ThreadPoolTaskScheduler taskScheduler = new ThreadPoolTaskScheduler();  
  24.     taskScheduler.setThreadNamePrefix("SockJS-");  
  25.     return taskScheduler;  
  26.   }  
  27.   
  28. }  

 

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

Java代码  收藏代码
  1. @Configuration  
  2. @EnableWebMvc  
  3. @EnableWebSocket//开启websocket  
  4. public class WebConfig extends WebMvcConfigurerAdapter implements WebSocketConfigurer {  
  5.   
  6.     @Override  
  7.     public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {  
  8.   
  9.         registry.addHandler(echoWebSocketHandler(), "/echo"); //提供符合W3C标准的Websocket数据  
  10.         registry.addHandler(snakeWebSocketHandler(), "/snake");  
  11.   
  12.         registry.addHandler(echoWebSocketHandler(), "/sockjs/echo").withSockJS();//提供符合SockJS的数据  
  13.         registry.addHandler(snakeWebSocketHandler(), "/sockjs/snake").withSockJS();  
  14.     }  
  15.   
  16.     @Bean  
  17.     public WebSocketHandler echoWebSocketHandler() {  
  18.         return new EchoWebSocketHandler(echoService());  
  19.     }  
  20.   
  21.     @Bean  
  22.     public WebSocketHandler snakeWebSocketHandler() {  
  23.         return new PerConnectionWebSocketHandler(SnakeWebSocketHandler.class);  
  24.     }  
  25.   
  26.     @Bean  
  27.     public DefaultEchoService echoService() {  
  28.         return new DefaultEchoService("Did you say \"%s\"?");  
  29.     }  
  30.   
  31.     // Allow serving HTML files through the default Servlet  
  32.   
  33.     @Override  
  34.     public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {  
  35.         configurer.enable();  
  36.     }  
  37.   
  38. }  

  

SockJS客户端代码:

<script type="text/javascript">
        var ws = null;

        function setConnected(connected) {
            document.getElementById('connect').disabled = connected;
            document.getElementById('disconnect').disabled = !connected;
            document.getElementById('echo').disabled = !connected;
        }

        function connect() {
            var target = document.getElementById('target').value;
            if (target == '') {
                alert('Please select server side connection implementation.');
                return;
            }
            if ('WebSocket' in window) {
                ws = new WebSocket(target);
            } else if ('MozWebSocket' in window) {
                ws = new MozWebSocket(target);
            } else {
                alert('WebSocket is not supported by this browser.');
                return;
            }
            ws.onopen = function () {
                setConnected(true);
                log('Info: WebSocket connection opened.');
            };
            ws.onmessage = function (event) {
                log('Received: ' + event.data);
            };
            ws.onclose = function () {
                setConnected(false);
                log('Info: WebSocket connection closed.');
            };
        }

        function disconnect() {
            if (ws != null) {
                ws.close();
                ws = null;
            }
            setConnected(false);
        }

        function echo() {
            if (ws != null) {
                var message = document.getElementById('message').value;
                log('Sent: ' + message);
                ws.send(message);
            } else {
                alert('WebSocket connection not established, please connect.');
            }
        }

        function updateTarget(target) {
            if (window.location.protocol == 'http:') {
                document.getElementById('target').value = 'ws://' + window.location.host + target;
            } else {
                document.getElementById('target').value = 'wss://' + window.location.host + target;
            }
        }

        function log(message) {
            var console = document.getElementById('console');
            var p = document.createElement('p');
            p.style.wordWrap = 'break-word';
            p.appendChild(document.createTextNode(message));
            console.appendChild(p);
            while (console.childNodes.length > 25) {
                console.removeChild(console.firstChild);
            }
            console.scrollTop = console.scrollHeight;
        }
    </script>

ws://localhost:8080/spring-websocket-test/echo

ws://localhost:8080/spring-websocket-test/echoSingleton

ws://localhost:8080/spring-websocket-test/echoAnnotated

 程序用maven打成war后用tomcat 8发布查看效果。

E:\myspace\spring-websocket-test-endpoint>mvn -DskipTests clean package

在target目录下生成了spring-websocket-test.war,部署到tomcat下,测试结果如下:

 

本例源码:spring-websocket-test-master.zip

posted on 2017-09-08 14:44  duanxz  阅读(1891)  评论(0编辑  收藏  举报