用html文件模拟设备在线状态，通过websocket协议实现消息推送。也就是模拟服务器向客户端推送消息。 直接上代码 1.配置pom
<!-- websocket --> <dependency> <groupId>javax.websocket</groupId> <artifactId>javax.websocket-api</artifactId> <version>1.1</version> </dependency>2.创建handler jfinal框架需要重写handler，放开拦截
import com.jfinal.handler.Handler; import com.jfinal.kit.StrKit; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.util.regex.Pattern; public class WebSocketHandler extends Handler { private Pattern filterUrlRegxPattern; public WebSocketHandler(String filterUrlRegx) { if (StrKit.isBlank(filterUrlRegx)) { throw new IllegalArgumentException("The para filterUrlRegx can not be blank."); } filterUrlRegxPattern = Pattern.compile(filterUrlRegx); } @Override public void handle(String target, HttpServletRequest request, HttpServletResponse response, boolean[] isHandled) { if (!filterUrlRegxPattern.matcher(target).find()) { next.handle(target, request, response, isHandled); } } }在config 文件中配置所创建的WebSocketHandler 3.创建最重要WebSocketServer处理类
import com.jfinal.kit.JsonKit; import javax.websocket.*; import javax.websocket.server.PathParam; import javax.websocket.server.ServerEndpoint; import java.io.IOException; import java.util.Map; import java.util.concurrent.ConcurrentHashMap; @ServerEndpoint("/websocket/{equ_no}") public class WebSocketServer { //用来存放每个客户端对应的WebSocket对象。 private static final Map<String, WebSocketServer> webSocketMap = new ConcurrentHashMap<String, WebSocketServer>(); //与某个客户端的连接会话，需要通过它来给客户端发送数据 private Session session; //设备编号 private String equNo; /** * 连接建立成功调用的方法 * 可选的参数。session为与某个客户端的连接会话，需要通过它来给客户端发送数据 */ @OnOpen public void onOpen(@PathParam("equ_no") String equNo, Session session) { this.equNo = equNo; this.session = session; webSocketMap.put(equNo, this); //System.out.println("onOpen_webSocketMap=" + JsonKit.toJson(webSocketMap)); System.out.println("设备" + this.equNo + "连接打开！当前在线设备为" + webSocketMap.size()); sendMessage(equNo, "设备" + equNo + "上线"); } /** * 连接关闭调用的方法 */ @OnClose public void onClose() { webSocketMap.remove(this.equNo); System.out.println("设备" + this.equNo + "连接关闭！当前在线设备为" + webSocketMap.size()); System.out.println("onClose_webSocketMap=" + JsonKit.toJson(webSocketMap)); } /** * 收到客户端消息后调用的方法 * message 客户端发送过来的消息 * session 可选的参数 */ @OnMessage public void onMessage(String message, Session session) { System.out.println("来自设备" + this.equNo + "的消息:" + message); System.out.println("session=" + session.getId()); sendMessage(message); } /** * 发生错误时调用 */ @OnError public void onError(Session session, Throwable error) { System.out.println("设备" + this.equNo + "发生错误"); System.out.println("连接" + session.getId() + "发生错误"); error.printStackTrace(); } /** * 指定发送消息 */ public void sendMessage(String equNo, String message) { WebSocketServer me = webSocketMap.get(equNo); if (me != null) { me.sendMessage(message); } else { //this.sendMessage(equNo + " 不在线"); System.out.println(equNo + " 不在线"); } } /** * 向客户端 发送消息 */ public void sendMessage(String message) { try { this.session.getBasicRemote().sendText(message); } catch (IOException e) { e.printStackTrace(); } } }4.测试Controller类
import cn.com.pajx.sn.core.mvc.controller.BaseAPIController; import com.jfinal.aop.Clear; import com.jfinal.aop.Inject; public class WebSocketTestController extends BaseAPIController { @Inject private WebSocketTestService webSocketTestService; @Clear public void testSend() { //String equNo = getPara("equ_no"); String equNos = "100001600001,100001600002"; String content = getPara("content"); String[] equNoArray = equNos.split(","); WebSocketServer server = new WebSocketServer(); for (String equNo : equNoArray) { server.sendMessage(equNo,"给" + equNo + "发送的信息:"+content); } renderAPISuccess("推送成功"); } }访问路径 5.测试HTML文件直接运行文件模拟上线 设备1：
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Java后端WebSocket的Tomcat实现</title> </head> <body> Welcome <br /> <input id="text" type="text" /> <button onclick="send()">发送消息</button> <hr /> <button onclick="closeWebSocket()">关闭WebSocket连接</button> <hr /> <div id="message"></div> </body> <script type="text/javascript" src="https://code.jquery.com/jquery-3.4.1.min.js"></script> <script type="text/javascript"> 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/websocket/100001600001"); } else { alert('当前浏览器 Not support websocket') } function newWebSocket(url) { if ('WebSocket' in window) { console.log("建立链接") websocket = new WebSocket(url); console.log(websocket) } else { alert('请使用火狐或谷歌浏览器') return; } } //连接发生错误的回调方法 websocket.onerror = function() { console.log("离线") setMessageInnerHTML("离线"); } //连接成功建立的回调方法 websocket.onopen = function() { setMessageInnerHTML("上线"); } //接收到消息的回调方法 websocket.onmessage = function(event) { console.log(event) setMessageInnerHTML(event.data); } //连接关闭的回调方法 websocket.onclose = function() { setMessageInnerHTML("下线"); } //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) { document.getElementById('message').innerHTML += innerHTML + '<br/>'; } //关闭WebSocket连接 function closeWebSocket() { websocket.close(); } //发送消息 function send() { var message = document.getElementById('text').value; websocket.send(message); } </script> </html>设备2：(与设备1代码一致，复制粘贴修改一下访问地址即可)
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Java后端WebSocket的Tomcat实现</title> </head> <body> Welcome <br /> <input id="text" type="text" /> <button onclick="send()">发送消息</button> <hr /> <button onclick="closeWebSocket()">关闭WebSocket连接</button> <hr /> <div id="message"></div> </body> <script type="text/javascript" src="https://code.jquery.com/jquery-3.4.1.min.js"></script> <script type="text/javascript"> 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/websocket/100001600002"); } else { alert('当前浏览器 Not support websocket') } function newWebSocket(url) { if ('WebSocket' in window) { console.log("建立链接") websocket = new WebSocket(url); console.log(websocket) } else { alert('请使用火狐或谷歌浏览器') return; } } //连接发生错误的回调方法 websocket.onerror = function() { console.log("离线") setMessageInnerHTML("离线"); } //连接成功建立的回调方法 websocket.onopen = function() { setMessageInnerHTML("上线"); } //接收到消息的回调方法 websocket.onmessage = function(event) { console.log(event) setMessageInnerHTML(event.data); } //连接关闭的回调方法 websocket.onclose = function() { setMessageInnerHTML("下线"); } //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) { document.getElementById('message').innerHTML += innerHTML + '<br/>'; } //关闭WebSocket连接 function closeWebSocket() { websocket.close(); } //发送消息 function send() { var message = document.getElementById('text').value; websocket.send(message); } </script> </html> 下面就可以访问测试路径，给设备1与设备2发送消息了。看效果ヽ(ー_ー)ノ如此便大功告成了。 每天记录一点点。
