spring4.0 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：

原文链接：https://www.cnblogs.com/duanxz/p/7491204.html

spring4.0 websocket简单应用

1、Java API for WebSocket(JSR-356)

1.1 Servlet容器扫描初始化

1.2 Spring 初始化

2、Spring WebSocket API

SockJS服务器端的支持

SockJS客户端代码：

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