WebSocket简介
- WebSocket是一种在单个TCP连接上进行全双工通信的协议。
- WebSocket使得客户端和服务器之间的数据交换变得更加简单,允许服务端主动向客户端推送数据。在WebSocket API中,浏览器和服务器只需要完成一次握手,两者之间就直接可以创建持久性的连接,并进行双向数据传输。
场景
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。