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+),tomcat7.0.55
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
@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 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 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) {
}
}
这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
使用sockjs时要注意
1、这两个的写法
websocket = new SockJS(http://localhost:8080/Origami/sockjs/webSocketServer);
2、web.xml中
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
true appServlet org.springframework.web.servlet.DispatcherServlet contextConfigLocation classpath*:servlet-context.xml 1 true
然后所有的filter中也加入
true
3、添加相关依赖
com.fasterxml.jackson.core jackson-annotations 2.3.0 com.fasterxml.jackson.core jackson-core 2.3.1 com.fasterxml.jackson.core jackson-databind 2.3.3
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