什么试WebSocket
WebSocket是一个连接，这个连接是客户端（页面）与服务端之间的连接，处理两者间通讯；
好处：HTML5定义了WebSocket协议，能更好的节省服务器资源和带宽，并且能够更实时地进行通讯,不需要每次发送请求接口获取数据，
使用场景：比如客户端登录后，出现的消息推送，每天定时广播推送给客户端消息等场景；
SpringBoot maven项目中实现
导入依赖：
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-websocket</artifactId></dependency>客户端和服务端怎么链接呢？前端实现也是固定的写法，只需要请求/websocket/{userId} 这个地址即可实现链接
前端js代码：
//判断当前浏览器是否支持WebSocket if ('WebSocket' in window) { websocket = new WebSocket("ws://" + document.location.host + "/WebChat/websocket/" + username + "/"+ _img); } else { alert('当前浏览器 Not support websocket') } java 实现websocket连接的代码:
package org.jeecg.modules.message.websocket;import com.alibaba.fastjson.JSONObject;import lombok.extern.slf4j.Slf4j;import org.jeecg.common.constant.WebsocketConst;import org.springframework.stereotype.Component;import javax.websocket.OnClose;import javax.websocket.OnError;import javax.websocket.OnMessage;import javax.websocket.OnOpen;import javax.websocket.Session;import javax.websocket.server.PathParam;import javax.websocket.server.ServerEndpoint;import java.io.IOException;import java.util.HashMap;import java.util.Map;import java.util.concurrent.CopyOnWriteArraySet;@Component@Slf4j@ServerEndpoint("/websocket/{userId}") //此注解相当于设置访问URLpublic class WebSocket { private Session session; private static final CopyOnWriteArraySet<WebSocket> webSockets = new CopyOnWriteArraySet<>(); private static final Map<String, Session> sessionPool = new HashMap<>(); @OnOpen public void onOpen(Session session, @PathParam(value = "userId") String userId) { try { this.session = session; webSockets.add(this); sessionPool.put(userId, session); log.info("【websocket消息】有新的连接，总数为: {}", webSockets.size()); } catch (Exception e) { } } @OnClose public void onClose(@PathParam(value = "userId") String userId) { try { webSockets.remove(this); sessionPool.remove(userId); log.info("【websocket消息】连接断开，总数为: {}", webSockets.size()); } catch (Exception e) { } } @OnMessage public void onMessage(String message) { log.debug("【websocket消息】收到客户端消息: {}", message); JSONObject obj = new JSONObject(); obj.put(WebsocketConst.MSG_CMD, WebsocketConst.CMD_CHECK);//业务类型 obj.put(WebsocketConst.MSG_TXT, "心跳响应");//消息内容 session.getAsyncRemote().sendText(obj.toJSONString()); } @OnError public void OnError(Session session, @PathParam(value = "userId") String userId, Throwable t) { try { if (session.isOpen()) { session.close(); } webSockets.remove(this); sessionPool.remove(userId); log.info("【websocket消息】连接[错误]断开，总数为: {}, 错误：{}", webSockets.size(), t.getMessage()); } catch (IOException e) { e.printStackTrace(); } } // 此为广播消息 public void sendAllMessage(String message) { log.info("【websocket消息】广播消息:" + message); for (WebSocket webSocket : webSockets) { try { if (webSocket.session.isOpen()) { webSocket.session.getAsyncRemote().sendText(message); } } catch (Exception e) { e.printStackTrace(); } } } // 此为单点消息 public void sendOneMessage(String userId, String message) { Session session = sessionPool.get(userId); if (session != null && session.isOpen()) { try { log.info("【websocket消息】 单点消息:" + message); session.getAsyncRemote().sendText(message); } catch (Exception e) { e.printStackTrace(); } } } // 此为单点消息(多人) public void sendMoreMessage(String[] userIds, String message) { for (String userId : userIds) { Session session = sessionPool.get(userId); if (session != null && session.isOpen()) { try { log.info("【websocket消息】 单点消息:" + message); session.getAsyncRemote().sendText(message); } catch (Exception e) { e.printStackTrace(); } } } }}在RunApplication中加入：
package org.jeecg.config;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.web.socket.server.standard.ServerEndpointExporter;@Configurationpublic class WebSocketConfig { @Bean public ServerEndpointExporter serverEndpointExporter() { return new ServerEndpointExporter(); } }可以编写一个test 测试连接
public class WebSocketTest { public static void main(String[] args) { try { // 创建WebSocket客户端 MyWebSocketClient myClient = new MyWebSocketClient(new URI("ws://127.0.0.1:9091/web/websocket/123333")); // 与服务端建立连接 myClient.connect(); while (!myClient.getReadyState().equals(ReadyState.OPEN)) { System.out.println("连接中。。。"); Thread.sleep(1000); } // 往websocket服务端发送数据 myClient.send("发送来自websocketClient 123333的消息"); Thread.sleep(1000); // 关闭与服务端的连接 // myClient.close(); }catch (Exception e){ e.printStackTrace(); } // write your code here }}实际开发使用：
package org.jeecg.modules.food.job;import com.alibaba.fastjson.JSONObject;import org.apache.commons.collections.CollectionUtils;import org.jeecg.common.constant.WebsocketConst;import org.jeecg.modules.food.entity.DailyMenu;import org.jeecg.modules.food.mapper.DailyMenuMapper;import org.jeecg.modules.message.websocket.WebSocket;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.scheduling.annotation.Scheduled;import org.springframework.stereotype.Component;import javax.annotation.Resource;import java.util.Calendar;import java.util.Date;import java.util.List;@Componentpublic class DailyMenuTask { @Resource private WebSocket webSocket; @Autowired private DailyMenuMapper dailyMenuMapper; @Scheduled(cron = "0 0 10,14 * * ?") public void pushDailyMenu() { DailyMenu dailyMenu = new DailyMenu(); Calendar cal = Calendar.getInstance(); cal.setTime(new Date()); cal.add(Calendar.DATE, 1); Date time = cal.getTime(); dailyMenu.setFoodDate(time); List<DailyMenu> dailyMenus = dailyMenuMapper.selectByDate(dailyMenu); if (CollectionUtils.isNotEmpty(dailyMenus)) { //创建业务消息信息 JSONObject obj = new JSONObject(); // 业务类型 obj.put(WebsocketConst.MSG_CMD, WebsocketConst.CMD_TOPIC); obj.put(WebsocketConst.MSG_ID, dailyMenus.get(0).getId()); obj.put(WebsocketConst.MSG_TXT, "订餐发布"); //全体发送 webSocket.sendAllMessage(obj.toJSONString()); } }}java 实现websocket的方式有很多种
- java 实现websocket一般两种方式，一种使用tomcat的websocket实现，比如上述使用这种方式无需别的任何配置，只需服务端一个处理类；
- 使用spring的websocket，spring与websocket整合需要spring 4.x，并且使用了socketjs，对不支持websocket的浏览器可以模拟websocket使用。实现WebSocketConfigurer接口的registerWebSocketHandlers方法加入自己WebSocketHandler接口的实现类。
- 使用spring stomp封装的方法，实现更简单，配置注入后通过@sendto就可向客户端发消息。
- 等等
来源地址：https://blog.csdn.net/rainAndyou/article/details/130678911
