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  • WebSocket

    1. WebSocket是HTML5开始提供的一种在单个 TCP 连接上进行全双工通讯的协议。

    2. 在WebSocket API中，浏览器和服务器只需要做一个握手的动作，然后，浏览器和服务器之间就形成了一条快速通道。两者之间就直接可以数据互相传送。
      浏览器通过 JavaScript 向服务器发出建立 WebSocket 连接的请求，连接建立以后，客户端和服务器端就可以通过 TCP 连接直接交换数据。
      当你获取 Web Socket 连接后，你可以通过 send() 方法来向服务器发送数据，并通过 onmessage 事件来接收服务器返回的数据

    3. spring整合websocket
    4. 添加maven依赖 
                  <!-- spring websocket 开始-->
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-messaging</artifactId>
			<version>4.0.6.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-websocket</artifactId>
			<version>4.0.6.RELEASE</version>
		</dependency>
				<dependency>
		    <groupId>javax.websocket</groupId>
		    <artifactId>javax.websocket-api</artifactId>
		    <version>1.0</version>
		    <scope>provided</scope>
		</dependency>
		<!-- spring websocket 结束-->
    5. 配置task注解applicationContext-task.xml 
      <?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:task="http://www.springframework.org/schema/task"  
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans     
        http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-4.0.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
        http://www.springframework.org/schema/tx
        http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
        http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-4.0.xsd"
        >
<!--     开启这个配置，spring才能识别@Scheduled注解    -->   
         <task:annotation-driven scheduler="qbScheduler" mode="proxy"/>  
    
         <task:scheduler id="qbScheduler" pool-size="10"/>  
    
    
    
</beans>
    6. 通过websocket定时刷新需要交互的数据 
      import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;

import com.alibaba.fastjson.JSON;
import com.founder.szhd.business.water.dto.WaterAlarmInfoDTO;
import com.founder.szhd.business.water.service.WaterAlarmInfoService;

/**
 * 通过webSocket定时刷新前端数量
 *
 */
@Component
public class FrontWebDataSchedule {
	
	private final static Logger logger = LoggerFactory.getLogger(FrontWebDataSchedule.class);
	
	@Autowired
	private WaterAlarmInfoService<WaterAlarmInfoDTO> waterAlarmInfoService;
	
	 @Bean//这个注解会从Spring容器拿出Bean
    public CustomWebSocketHandler infoHandler() {
 
        return new CustomWebSocketHandler();
    }
	 
	 /**
	     * @return void
	     * @throws
	     * @Description: TODO   定时更新报警信息
	     * @author xiehui
	     * @date 2018/8/25 上午11:58
	     */
	    @Scheduled(fixedDelayString = "1500")
	    protected void updateWarnInfo() throws IOException {
	    	 Map<String, WebSocketSession> users = infoHandler().getUsers();
	        System.out.println(" 定时更新报警信息");
	        
	        Set<String> mchNos = users.keySet();
	        WebSocketSession session = null;
	        for (String mchNo : mchNos) {
	            session = users.get(mchNo);
				String departId = String.valueOf(session.getAttributes().get("departId"));
				Map warnInfoMap = new HashMap();
				warnInfoMap.put("navi", getNaviWarnInfo(departId));
				String message = JSON.toJSONString(warnInfoMap);
				infoHandler().sendMessageByDepartment(new TextMessage(message), departId);
	        }
	    }
	    
	    /**
	     * 查询报警信息
	     * @param key
	     * @return
	     */
	    private Map<String, Object> getNaviWarnInfo(String key) {
	        Map<String, Object> waterMap = null;
	        try {
	            waterMap = waterAlarmInfoService.findWarningPro(key);
	        } catch (Exception e) {
	            logger.error(e.getMessage());
	        }
	        return waterMap;
	    }
	    
	 

}　
    7. springboot对websocket支持很友好，只需要继承webSocketHandler类，重写几个方法就可以了，这个类的作用就是在连接成功前和成功后增加一些额外的功能 
      import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.socket.CloseStatus;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketHandler;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.handler.TextWebSocketHandler;

/**
 * 创建一个WebSocket server
 * 
 *
 */
@Service
public class CustomWebSocketHandler extends TextWebSocketHandler implements WebSocketHandler {
    private Logger logger = LoggerFactory.getLogger(CustomWebSocketHandler.class);
    // 在线用户列表
    private static final Map<String, WebSocketSession> users;
    
 // 用户标识
    private static final String CLIENT_ID = "username";
    
    @Autowired
    private FrontWebDataSchedule frontWebData;


    static {
        users = new HashMap<>();
    }
    

    @Override
    public void afterConnectionEstablished(WebSocketSession session) throws Exception {
    	logger.info("成功建立websocket-spring连接");
        String mchNo = getMchNo(session);
        if (StringUtils.isNotEmpty(mchNo)) {
            users.put(mchNo, session);
           // session.sendMessage(new TextMessage("成功建立websocket-spring连接"));
          //连接后第一次推送当前报警信息
            frontWebData.updateWarnInfo();
            logger.info("用户标识：{}，Session：{}", mchNo, session.toString());
        }
        
    }

    @Override
    public void handleTextMessage(WebSocketSession session, TextMessage message) {
        logger.info("收到客户端消息：{}", message.getPayload());
        String mchNo = getMchNo(session);
        if (StringUtils.isNotEmpty(mchNo)) {
            // 获取提交过来的消息详情
            logger.debug("收到用户 " + mchNo + "的消息:" + message.toString());
        }
        
        
    }

    @Override
    public void handleTransportError(WebSocketSession session, Throwable exception) throws Exception {
    	
    	if (session.isOpen()) {
            session.close();
        }
        logger.info("连接出错");
        users.remove(getMchNo(session));
    	
    }

    @Override
    public void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception {
    	 logger.info("连接已关闭：" + status);
         users.remove(getMchNo(session));
    }

    @Override
    public boolean supportsPartialMessages() {
        return false;
    }

    
    /**
     * 发送信息给指定用户
     * @Title: sendMessageToUser 
     * @Description: TODO
     * @Date 2018年8月21日 上午11:01:08 
     * @author OnlyMate
     * @param mchNo
     * @param message
     * @return
     */
    public boolean sendMessageToUser(String mchNo, TextMessage message) {
    	
    	if (users.get(mchNo) == null)
            return false;
        WebSocketSession session = users.get(mchNo);
        logger.info("sendMessage：{} ,msg：{}", session, message.getPayload());
        if (!session.isOpen()) {
            logger.info("客户端:{},已断开连接，发送消息失败", mchNo);
            return false;
        }
        try {
            session.sendMessage(message);
        } catch (IOException e) {
            logger.info("sendMessageToUser method error：{}", e);
            return false;
        }
        return true;
    }

    /**
     * 广播信息
     * @Title: sendMessageToAllUsers 
     * @Description: TODO
     * @Date 2018年8月21日 上午11:01:14 
     * @author OnlyMate
     * @param message
     * @return
     */
    public boolean sendMessageToAllUsers(TextMessage message) {
    	boolean allSendSuccess = true;
        Set<String> mchNos = users.keySet();
        WebSocketSession session = null;
        for (String mchNo : mchNos) {
            try {
                session = users.get(mchNo);
                if (session.isOpen()) {
                    session.sendMessage(message);
                }else {
                    logger.info("客户端:{},已断开连接，发送消息失败", mchNo);
                }
            } catch (IOException e) {
                logger.info("sendMessageToAllUsers method error：{}", e);
                allSendSuccess = false;
            }
        }

        return allSendSuccess;
    }
    
    /**
     * @Description: TODO 发送信息给相同部门
     * @author xiehui
     * @date 2018/8/25 下午4:49
     */
    public void sendMessageByDepartment(TextMessage message, String departId) {
    	
    	Set<String> mchNos = users.keySet();
        WebSocketSession session = null;
        for (String mchNo : mchNos) {
            try {
                session = users.get(mchNo);
                if (session.isOpen() && departId.equals(String.valueOf(session.getAttributes().get("departId")))) {
                	session.sendMessage(message);
                }
            } catch (IOException e) {
                logger.info("sendMessageToAllUsers method error：{}", e);
            }
        }
    }
    
    /**
     * 获取用户标识
     * @Title: getMchNo 
     * @Description: TODO
     * @Date 2018年8月21日 上午11:01:01 
     * @author OnlyMate
     * @param session
     * @return
     */
    private String getMchNo(WebSocketSession session) {
        try {
            String mchNo = session.getAttributes().get(CLIENT_ID).toString();
            return mchNo;
        } catch (Exception e) {
            return null;
        }
    }

	public static Map<String, WebSocketSession> getUsers() {
		return users;
	}
    
    
    
}
    8. 把websocketSession和httpsession对应起来，这样就能根据当前不同的session，定向对websocketSession进行数据返回;在查询资料之后，发现spring中有一个拦截器接口，HandshakeInterceptor，可以实现这个接口，来拦截握手过程，向其中添加属性 
      import java.util.Map;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.server.ServerHttpRequest;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.http.server.ServletServerHttpRequest;
import org.springframework.web.socket.WebSocketHandler;
import org.springframework.web.socket.server.HandshakeInterceptor;

import com.founder.commons.web.login.dto.LoginUser;

/**
 * WebSocket握手时的拦截器
 * @ClassName: CustomWebSocketInterceptor 
 *
 */
public class CustomWebSocketInterceptor implements HandshakeInterceptor {
    private Logger logger = LoggerFactory.getLogger(CustomWebSocketInterceptor.class);
    /**
     * 关联HeepSession和WebSocketSession，
     * beforeHandShake方法中的Map参数 就是对应websocketSession里的属性
     */
    @Override
    public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler handler, Map<String, Object> map) throws Exception {
        if (request instanceof ServletServerHttpRequest) {
            logger.info("*****beforeHandshake******");
            HttpServletRequest httpServletRequest = ((ServletServerHttpRequest) request).getServletRequest();
            HttpSession session = httpServletRequest.getSession(true);
            
            if (session != null) {
            	
            	 ///使用userName区分WebSocketHandler，以便定向发送消息
            	LoginUser	systemLoginName =  (LoginUser) session.getAttribute("systemLoginName");   //一般直接保存user实体
                if (systemLoginName!=null) {
                	 map.put("sessionId",session.getId());
                	map.put("username",systemLoginName.getUserName());
                	map.put("departId", systemLoginName.getDepartmentID());
                }
               
            }
        }
        return true;
    }

    @Override
    public void afterHandshake(ServerHttpRequest serverHttpRequest, ServerHttpResponse serverHttpResponse, WebSocketHandler webSocketHandler, Exception e) {
        logger.info("******afterHandshake******");
    }
}　　
    9. 配置类向Spring中注入handler 
      package com.founder.commons.websocket;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.WebSocketHandler;
import org.springframework.web.socket.config.annotation.EnableWebSocket;
import org.springframework.web.socket.config.annotation.WebSocketConfigurer;
import org.springframework.web.socket.config.annotation.WebSocketHandlerRegistry;

import com.founder.szhd.websocket.CustomWebSocketHandler;

/**
 * websocket的配置类  
 *
 */
@Configuration
@EnableWebSocket
public class CustomWebSocketConfig implements WebSocketConfigurer {
    

    @Override
    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        registry.addHandler(customWebSocketHandler(), "/webSocketBySpring/customWebSocketHandler.do").addInterceptors(new CustomWebSocketInterceptor());
        registry.addHandler(customWebSocketHandler(), "/sockjs/webSocketBySpring/customWebSocketHandler").addInterceptors(new CustomWebSocketInterceptor()).withSockJS();
    }

    @Bean
    public WebSocketHandler customWebSocketHandler() {
        return new CustomWebSocketHandler();
    }
}　　
    10. 前端js中调用 
      

      var websocket = null; 
          //判断当前浏览器是否支持WebSocket  
          //判断当前浏览器是否支持WebSocket  
          if('WebSocket' in window) {
              websocket = new WebSocket("ws://localhost:8080/xxxx/webSocketBySpring/customWebSocketHandler.do");  
          } else if('MozWebSocket' in window) {
              websocket = new MozWebSocket("ws://localhost:8080/xxxx/webSocketBySpring/customWebSocketHandler.do");
          } else {
              websocket = new SockJS("http://localhost:8080/xxxx/sockjs/webSocketBySpring/customWebSocketHandler.do");
          }
          //连接发生错误的回调方法  
          websocket.onerror = function () {  
              setMessageInnerHTML("WebSocket连接发生错误");  
          };  
        
          //连接成功建立的回调方法  
          websocket.onopen = function () {  
              setMessageInnerHTML("WebSocket连接成功");  
          }  
        
          //接收到消息的回调方法  
          websocket.onmessage = function (event) {  
              setMessageInnerHTML(event.data);  
          }  
        
          //连接关闭的回调方法  
          websocket.onclose = function () {  
              setMessageInnerHTML("WebSocket连接关闭");  
          }  
        
          //监听窗口关闭事件，当窗口关闭时，主动去关闭websocket连接，防止连接还没断开就关闭窗口，server端会抛异常。  
          window.onbeforeunload = function () {  
              closeWebSocket();  
          }  
        
          //将消息显示在网页上  
          function setMessageInnerHTML(innerHTML) {  
              alert(innerHTML);
          }  
        
          //关闭WebSocket连接  
          function closeWebSocket() {  
              websocket.close();  
          }  
        
          //发送消息  
          function send() {  
              var message = "发送消息";  
              websocket.send(message);  
          }
      


      


      11. 

    11. 

      

      补充说明：
      

      setAllowedOrigins("*")一定要加上，不然只有访问localhost，其他的不予许访问
      

      setAllowedOrigins(String[] domains),允许指定的域名或IP(含端口号)建立长连接，如果只允许自家域名访问，这里轻松设置。如果不限时使用"*"号，如果指定了域名，则必须要以http或https开头
      

      经查阅官方文档springwebsocket 4.1.5版本前默认支持跨域访问，之后的版本默认不支持跨域，需要设置
      


      使用withSockJS()的原因：
      

      　　一些浏览器中缺少对WebSocket的支持,因此，回退选项是必要的，而Spring框架提供了基于SockJS协议的透明的回退选项。
      

      SockJS的一大好处在于提供了浏览器兼容性。优先使用原生WebSocket，如果在不支持websocket的浏览器中，会自动降为轮询的方式。 
      除此之外，spring也对socketJS提供了支持。
      

      如果代码中添加了withSockJS()如下，服务器也会自动降级为轮询。
      

      registry.addEndpoint("/coordination").withSockJS();
      

      SockJS的目标是让应用程序使用WebSocket API，但在运行时需要在必要时返回到非WebSocket替代，即无需更改应用程序代码。
      

      SockJS是为在浏览器中使用而设计的。它使用各种各样的技术支持广泛的浏览器版本。对于SockJS传输类型和浏览器的完整列表，可以看到SockJS客户端页面。 
      传输分为3类:WebSocket、HTTP流和HTTP长轮询（按优秀选择的顺序分为3类）
      


      


      12. 


    

    
    
                
    
                
              
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                原文地址：https://www.cnblogs.com/sily-boy/p/14029189.html
              
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