Spring和Websocket相結合實現消息的推送

本文主要有三個步驟

一、用戶登陸後創建websocket鏈接，默認選擇websocket鏈接，若是瀏覽器不支持，則使用sockjs進行模擬鏈接
二、創建鏈接後，服務端返回該用戶的未讀消息
三、服務端進行相關操做後，推送給某一個用戶或者全部用戶新消息 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的配置文件中配置對此類的自動掃描

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

@Configuration
@EnableWebMvc
@EnableWebSocket

這三個大體意思是使這個類支持以@Bean的方式加載bean，而且支持springmvc和websocket，不是很準確大體這樣，試了一下@EnableWebMvc不加也沒什麼影響，@Configuration原本就支持springmvc的自動掃描

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

用來註冊websocket server實現類，第二個參數是訪問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;
}
/**
* 給全部在線用戶發送消息
*
* @param message
*/
public void sendMessageToUsers(TextMessage message) {
for (WebSocketSession user : users) {
try {
if (user.isOpen()) {
user.sendMessage(message);
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
/**
* 給某個用戶發送消息
*
* @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;
}
}
}
}

相關內容你們一看就能明白，就很少解釋了

而後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，以便定向發送消息
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) {
}
}

這個的主要做用是取得當前請求中的用戶名，而且保存到當前的WebSocketHandler中，以便肯定WebSocketHandler所對應的用戶，具體可參考HttpSessionHandshakeInterceptor

用戶登陸創建websocket鏈接

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時要注意

一、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(<a href="http://localhost:8080/Origami/sockjs/webSocketServer">http://localhost:8080/Origami/sockjs/webSocketServer</a>);

二、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+

而後在這個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>

而後全部的filter中也加入

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

三、添加相關依賴

<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，如今websocket能夠正常創建起來了

返回用戶未讀的消息

當鏈接創建後，會進入SystemWebSocketHandler的afterConnectionEstablished方法，代碼看上邊，取出WebSocketHandshakeInterceptor中保存的用戶名

查詢信息後使用session.sendMessage(new TextMessage(count + ""));返回給用戶，從哪來回哪去

服務端推送消息給用戶

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

在這裏可使用sendMessageToUser給某個用戶推送信息，也可使用sendMessageToUsers給全部用戶推送信息