Spring+Websocket實現訊息的推送

天府雲創發表於2016-12-19
SpringWeb
摘要: 本文主要有三個步驟 1、使用者登入後建立websocket連線，預設選擇websocket連線，如果瀏覽器不支援，則使用sockjs進行模擬連線 2、建立連線後，服務端返回該使用者的未讀訊息 3、服務端進行相關操作後，推送給某一個使用者或者所有使用者新訊息 相關環境 Spring4.0.6(要選擇4.0+),tomcat7.0.55

Websocet服務端實現

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();
    }

}
不要忘記在springmvc的配置檔案中配置對此類的自動掃描 

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

@Configuration

@EnableWebMvc
@EnableWebSocket
這三個大致意思是使這個類支援以@Bean的方式載入bean，並且支援springmvc和websocket，不是很準確大致這樣，試了一下@EnableWebMvc不加也沒什麼影響，@Configuration本來就支援springmvc的自動掃描


registry.addHandler(systemWebSocketHandler(),"/webSocketServer").addInterceptors(new WebSocketHandshakeInterceptor())
用來註冊websocket server實現類，第二個引數是訪問websocket的地址 



registry.addHandler(systemWebSocketHandler(), "/sockjs/webSocketServer").addInterceptors(new WebSocketHandshakeInterceptor())
                .withSockJS();
    }
這個是使用Sockjs的註冊方法


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){
            //查詢未讀訊息
            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;
    }

    /**
     * 給所有線上使用者傳送訊息
     *
     * @param message
     */
    public void sendMessageToUsers(TextMessage message) {
        for (WebSocketSession user : users) {
            try {
                if (user.isOpen()) {
                    user.sendMessage(message);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 給某個使用者傳送訊息
     *
     * @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;
            }
        }
    }
}



相關內容大家一看就能明白，就不多解釋了


然後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區分WebSocketHandler，以便定向傳送訊息
                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) {

    }
}

這個的主要作用是取得當前請求中的使用者名稱，並且儲存到當前的WebSocketHandler中，以便確定WebSocketHandler所對應的使用者，具體可參考HttpSessionHandshakeInterceptor

使用者登入建立websocket連線

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時要注意

1、這兩個的寫法

<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
這兩個的版本都要是3.0+


然後在這個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>

然後所有的filter中也加入

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


3、新增相關依賴

<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，現在websocket可以正常建立起來了



返回使用者未讀的訊息

當連線建立後，會進入SystemWebSocketHandler的afterConnectionEstablished方法，程式碼看上邊，取出WebSocketHandshakeInterceptor中儲存的使用者名稱

查詢資訊後使用session.sendMessage(new TextMessage(count + ""));返回給使用者，從哪來回哪去


服務端推送訊息給使用者

@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){
        //無關程式碼都省略了
        int unReadNewsCount = adminService.getUnReadNews(username);
        systemWebSocketHandler().sendMessageToUser(username, new TextMessage(unReadNewsCount + ""));
        return result;
    }
}

在這裡可以使用sendMessageToUser給某個使用者推送資訊，也可以使用sendMessageToUsers給所有使用者推送資訊

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