介绍
前后端分离项目中前端大多使用ajax调用服务器接口，但是如果要实现消息提醒功能该如何实现消息推送
webSocket的做法是发送一个持久性的请求，并进行双向数据传输。
- 第一步 导入依赖
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-websocket</artifactId>
</dependency>
<!--Lombok能通过注解的方式，在编译时自动为属性生成构造器、getter/setter、equals、hashcode、toString方法。-->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.8</version>
<scope>provided</scope>
</dependency>
- 第二步 webSocket服务
import lombok.extern.slf4j.Slf4j;
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.ServerEndpoint;
import java.io.IOException;
import java.util.concurrent.CopyOnWriteArraySet;
@Slf4j
@ServerEndpoint(value = "/websocket")
@Component
public class WebSocketServer
{
//静态变量，用来记录当前在线连接数。应该把它设计成线程安全的。
private static int onlineCount = 0;
//concurrent包的线程安全Set，用来存放每个客户端对应的MyWebSocket对象。
private static CopyOnWriteArraySet<WebSocketServer> webSocketSet = new CopyOnWriteArraySet<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;
/**
* 连接建立成功调用的方法
*/
@OnOpen
public void onOpen(Session session)
{
this.session = session;
webSocketSet.add(this); //加入set中
addOnlineCount(); //在线数加1
log.info("有新连接加入！当前在线人数为" + getOnlineCount());
try
{
sendMessage("连接成功");
}
catch (IOException e)
{
log.error("websocket IO异常");
}
}
/**
* 连接关闭调用的方法
*/
@OnClose
public void onClose()
{
webSocketSet.remove(this); //从set中删除
subOnlineCount(); //在线数减1
log.info("有一连接关闭！当前在线人数为" + getOnlineCount());
}
/**
* 收到客户端消息后调用的方法
*
* @param message 客户端发送过来的消息
*/
@OnMessage
public void onMessage(String message, Session session)
{
log.info("来自客户端的消息:" + message);
//群发消息
for (WebSocketServer item : webSocketSet)
{
try
{
item.sendMessage(message);
}
catch (IOException e)
{
e.printStackTrace();
}
}
}
/**
* @param session
* @param error
*/
@OnError
public void onError(Session session, Throwable error)
{
log.error("发生错误");
error.printStackTrace();
}
public void sendMessage(String message) throws IOException
{
this.session.getBasicRemote().sendText(message);
}
/**
* 群发自定义消息
*/
public static void sendInfo(String message) throws IOException
{
log.info(message);
for (WebSocketServer item : webSocketSet)
{
try
{
item.sendMessage(message);
}
catch (IOException e)
{
continue;
}
}
}
public static synchronized int getOnlineCount()
{
return onlineCount;
}
public static synchronized void addOnlineCount()
{
WebSocketServer.onlineCount++;
}
public static synchronized void subOnlineCount()
{
WebSocketServer.onlineCount--;
}
}
- 第三步 配置
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.server.standard.ServerEndpointExporter;
@Configuration
public class WebSocketConfig
{
@Bean
public ServerEndpointExporter serverEndpointExporter()
{
return new ServerEndpointExporter();
}
}
- 第四步 写Controller
package com.hc.demo.controller;
import com.hc.demo.service.WebSocketServer;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
@Controller
public class WebSocketController
{
@RequestMapping(value = "/pushVideoListToWeb", method = RequestMethod.POST, consumes = "application/json")
public @ResponseBody
Map<String, Object> pushVideoListToWeb(@RequestBody Map<String, Object> param)
{
Map<String, Object> result = new HashMap<String, Object>();
try
{
WebSocketServer.sendInfo("有新客户呼入");
result.put("operationResult", true);
}
catch (IOException e)
{
result.put("operationResult", true);
}
return result;
}
}
- 第五步 前端调用
<!DOCTYPE HTML>
<html>
<head>
<title>My WebSocket</title>
</head>
<body>
Welcome<br/>
<input id="text" type="text" /><button onclick="send()">Send</button> <button onclick="closeWebSocket()">Close</button>
<div id="message">
</div>
</body>
<script type="text/javascript">
var websocket = null;
//判断当前浏览器是否支持WebSocket
if('WebSocket' in window){
websocket = new WebSocket("ws://localhost:9898/websocket");
}
else{
alert('Not support websocket')
}
//连接发生错误的回调方法
websocket.onerror = function(){
setMessageInnerHTML("error");
};
//连接成功建立的回调方法
websocket.onopen = function(event){
setMessageInnerHTML("open");
}
//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("close");
}
//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(){
websocket.close();
}
//将消息显示在网页上
function setMessageInnerHTML(innerHTML){
document.getElementById('message').innerHTML += innerHTML + '<br/>';
}
//关闭连接
function closeWebSocket(){
websocket.close();
}
//发送消息
function send(){
var message = document.getElementById('text').value;
websocket.send(message);
}
</script>
</html>
好了 就这样 可以试一试效果
