【转】Spring+Websocket实现消息的推送

本文主要有三个步骤 1、用户登录后建立websocket连接，默认选择websocket连接，如果浏览器不支持，则使用sockjs进行模拟连接 2、建立连接后，服务端返回该用户的未读消息 3、服务端进行相关操作后，推送给某一个用户或者所有用户新消息相关环境 Spring4.0.6(要选择4.0+),tomcat7.0.5

Websocet服务端实现

WebSocketConfig.java

@Configuration

@EnableWebMvc

@EnableWebSocket

public class WebSocketConfig extends WebMvcConfigurerAdapter implements WebSocketConfigurer {

    @Override

    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {

        registry.addHandler(systemWebSocketHandler(),"/webSocketServer").addInterceptors(new WebSocketHandshakeInterceptor());

        registry.addHandler(systemWebSocketHandler(), "/sockjs/webSocketServer").addInterceptors(new WebSocketHandshakeInterceptor())

                .withSockJS();

    }

    @Bean

    public WebSocketHandler systemWebSocketHandler(){

        return new SystemWebSocketHandler();

    }

}

不要忘记在springmvc的配置文件中配置对此类的自动扫描

<context:component-scan base-package="com.ldl.origami.websocket" />

@Configuration

@EnableWebMvc
@EnableWebSocket
这三个大致意思是使这个类支持以@Bean的方式加载bean，并且支持springmvc和websocket，不是很准确大致这样，试了一下@EnableWebMvc不加也没什么影响，@Configuration本来就支持springmvc的自动扫描

registry.addHandler(systemWebSocketHandler(),"/webSocketServer").addInterceptors(new WebSocketHandshakeInterceptor())

用来注册websocket server实现类，第二个参数是访问websocket的地址

registry.addHandler(systemWebSocketHandler(), "/sockjs/webSocketServer").addInterceptors(new WebSocketHandshakeInterceptor())

                .withSockJS();

    }

这个是使用Sockjs的注册方法
首先SystemWebSocketHandler.java

public class SystemWebSocketHandler implements WebSocketHandler {

    private static final Logger logger;

    private static final ArrayList<WebSocketSession> users;

    static {

        users = new ArrayList<>();

        logger = LoggerFactory.getLogger(SystemWebSocketHandler.class);

    }

    @Autowired

    private WebSocketService webSocketService;

    @Override

    public void afterConnectionEstablished(WebSocketSession session) throws Exception {

        logger.debug("connect to the websocket success......");

        users.add(session);

        String userName = (String) session.getAttributes().get(Constants.WEBSOCKET_USERNAME);

        if(userName!= null){

            //查询未读消息

            int count = webSocketService.getUnReadNews((String) session.getAttributes().get(Constants.WEBSOCKET_USERNAME));

            session.sendMessage(new TextMessage(count + ""));

        }

    }

    @Override

    public void handleMessage(WebSocketSession session, WebSocketMessage<?> message) throws Exception {

        //sendMessageToUsers();

    }

    @Override

    public void handleTransportError(WebSocketSession session, Throwable exception) throws Exception {

        if(session.isOpen()){

            session.close();

        }

        logger.debug("websocket connection closed......");

        users.remove(session);

    }

    @Override

    public void afterConnectionClosed(WebSocketSession session, CloseStatus closeStatus) throws Exception {

        logger.debug("websocket connection closed......");

        users.remove(session);

    }

    @Override

    public boolean supportsPartialMessages() {

        return false;

    }

    /**

     * 给所有在线用户发送消息

     *

     * @param message

     */

    public void sendMessageToUsers(TextMessage message) {

        for (WebSocketSession user : users) {

            try {

                if (user.isOpen()) {

                    user.sendMessage(message);

                }

            } catch (IOException e) {

                e.printStackTrace();

            }

        }

    }

    /**

     * 给某个用户发送消息

     *

     * @param userName

     * @param message

     */

    public void sendMessageToUser(String userName, TextMessage message) {

        for (WebSocketSession user : users) {

            if (user.getAttributes().get(Constants.WEBSOCKET_USERNAME).equals(userName)) {

                try {

                    if (user.isOpen()) {

                        user.sendMessage(message);

                    }

                } catch (IOException e) {

                    e.printStackTrace();

                }

                break;

            }

        }

    }

}

相关内容大家一看就能明白，就不多解释了

然后WebSocketHandshakeInterceptor.java

public class WebSocketHandshakeInterceptor implements HandshakeInterceptor {

    private static Logger logger = LoggerFactory.getLogger(HandshakeInterceptor.class);

    @Override

    public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Map<String, Object

                > attributes) throws Exception {

        if (request instanceof ServletServerHttpRequest) {

            ServletServerHttpRequest servletRequest = (ServletServerHttpRequest) request;

            HttpSession session = servletRequest.getServletRequest().getSession(false);

            if (session != null) {

                //使用userName区分WebSocketHandler，以便定向发送消息

                String userName = (String) session.getAttribute(Constants.SESSION_USERNAME);

                attributes.put(Constants.WEBSOCKET_USERNAME,userName);

            }

        }

        return true;

    }

    @Override

    public void afterHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Exception exception) {

    }

}

个的主要作用是取得当前请求中的用户名，并且保存到当前的WebSocketHandler中，以便确定WebSocketHandler所对应的用户，具体可参考HttpSessionHandshakeInterceptor

用户登录建立websocket连接

index.jsp

<script type="text/javascript" src="http://localhost:8080/Origami/websocket/sockjs-0.3.min.js"></script>

        <script>

            var websocket;

            if ('WebSocket' in window) {

                websocket = new WebSocket("ws://localhost:8080/Origami/webSocketServer");

            } else if ('MozWebSocket' in window) {

                websocket = new MozWebSocket("ws://localhost:8080/Origami/webSocketServer");

            } else {

                websocket = new SockJS("http://localhost:8080/Origami/sockjs/webSocketServer");

            }

            websocket.onopen = function (evnt) {

            };

            websocket.onmessage = function (evnt) {

                $("#msgcount").html("(<font color='red'>"+evnt.data+"</font>)")

            };

            websocket.onerror = function (evnt) {

            };

            websocket.onclose = function (evnt) {

            }

        </script>

使用sockjs时要注意

1、这两个的写法

<script type="text/javascript" src="http://localhost:8080/Origami/websocket/sockjs-0.3.min.js"></script>

websocket = new SockJS("http://localhost:8080/Origami/sockjs/webSocketServer");

2、web.xml中

<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"

    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_1.xsd">

version

web-app_3_1.xsd

这两个的版本都要是3.0+

然后在这个servlet中加入

<async-supported>true</async-supported>

<servlet>

        <servlet-name>appServlet</servlet-name>

        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>

        <init-param>

            <param-name>contextConfigLocation</param-name>

            <param-value>classpath*:servlet-context.xml</param-value>

        </init-param>

        <load-on-startup>1</load-on-startup>

        <async-supported>true</async-supported>

    </servlet>

然后所有的filter中也加入

<async-supported>true</async-supported>

3、添加相关依赖

<dependency>

            <groupId>com.fasterxml.jackson.core</groupId>

            <artifactId>jackson-annotations</artifactId>

            <version>2.3.0</version>

        </dependency>

        <dependency>

            <groupId>com.fasterxml.jackson.core</groupId>

            <artifactId>jackson-core</artifactId>

            <version>2.3.1</version>

        </dependency>

        <dependency>

            <groupId>com.fasterxml.jackson.core</groupId>

            <artifactId>jackson-databind</artifactId>

            <version>2.3.3</version>

        </dependency>

好了，现在websocket可以正常建立起来了

返回用户未读的消息

当连接建立后，会进入SystemWebSocketHandler的afterConnectionEstablished方法，代码看上边，取出WebSocketHandshakeInterceptor中保存的用户名

查询信息后使用session.sendMessage(new TextMessage(count + “”));返回给用户，从哪来回哪去

服务端推送消息给用户

@Controller

public class AdminController {

    static Logger logger = LoggerFactory.getLogger(AdminController.class);

    @Autowired(required = false)

    private AdminService adminService;

    @Bean

    public SystemWebSocketHandler systemWebSocketHandler() {

        return new SystemWebSocketHandler();

    }

    @RequestMapping("/auditing")

    @ResponseBody

    public String auditing(HttpServletRequest request){

        //无关代码都省略了

        int unReadNewsCount = adminService.getUnReadNews(username);

        systemWebSocketHandler().sendMessageToUser(username, new TextMessage(unReadNewsCount + ""));

        return result;

    }

}

在这里可以使用sendMessageToUser给某个用户推送信息，也可以使用sendMessageToUsers给所有用户推送信息

原文地址：https://my.oschina.net/ldl123292/blog/304360