先说BUG处理，遇到提示异步问题 Async support must be enabled on a servlet and for all filters involved in async request processing. This is done in Java code using the Servlet API or by adding "<async-supported>true</async-supported>" to servlet and filter declarations in web.xml.
springboot在@WebFilter注解处，加入urlPatterns = { "/*" },asyncSupported = true
springmvc在web.xml处理
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
version="3.0">
<filter-mapping>
<filter-name>shiroFilter</filter-name>
<url-pattern>/*</url-pattern>
<dispatcher>REQUEST</dispatcher>
<dispatcher>ASYNC</dispatcher>
</filter-mapping>
- demo1，服务器间隔一定时间推送内容
-
接口方法
@GetMapping(path = "/sse/{userId}",produces = MediaType.TEXT_EVENT_STREAM_VALUE )
public Flux<ServerSentEvent<String>> sse(@PathVariable String userId) {
// 每两秒推送一次
return Flux.interval(Duration.ofSeconds(2)).map(seq->
Tuples.of(seq, LocalDateTime.now())).log()//序号和时间
.map(data-> ServerSentEvent.<String>builder().id(userId).data(data.getT1().toString()).build());//推送内容}
2.前端代码
<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8"/>
<title>服务器推送事件</title>
</head>
<body>
<div>
<div id="data"></div>
<div id="result"></div><br/>
</div>
<script th:inline="javascript" >
//服务器推送事件
if (typeof (EventSource) !== "undefined") {
var source1 = new EventSource("http://localhost:9000/api/admin/test/sse/1");
//当抓取到消息时
source1.onmessage = function (evt) {
document.getElementById("data").innerHTML = document.getElementById("data").innerHTML+"股票行情：" + evt.data;
};
} else {
//注意：ie浏览器不支持
document.getElementById("result").innerHTML = "抱歉，你的浏览器不支持 server-sent 事件...";
var xhr;
var xhr2;
if (window.XMLHttpRequest){
//IE7+, Firefox, Chrome, Opera, Safari浏览器支持该方法
xhr=new XMLHttpRequest();
xhr2=new XMLHttpRequest();
}else{
//IE6, IE5 浏览器不支持，使用ActiveXObject方法代替
xhr=new ActiveXObject("Microsoft.XMLHTTP");
xhr2=new ActiveXObject("Microsoft.XMLHTTP");
}
console.log(xhr);
console.log(xhr2);
xhr.open('GET', '/sse/countDown');
xhr.send(null);//发送请求
xhr.onreadystatechange = function() {
console.log("s响应状态：" + xhr.readyState);
//2是空响应，3是响应一部分，4是响应完成
if (xhr.readyState > 2) {
//这儿可以使用response(对应json)与responseText（对应text）
var newData = xhr.response.substr(xhr.seenBytes);
newData = newData.replace(/\n/g, "#");
newData = newData.substring(0, newData.length - 1);
var data = newData.split("#");
console.log("获取到的数据：" + data);
document.getElementById("result").innerHTML = data;
//长度重新赋值,下次截取时需要使用
xhr.seenBytes = xhr.response.length;
}
}
xhr2.open('GET', '/sse/retrieve');
xhr2.send(null);//发送请求
xhr2.onreadystatechange = function() {
console.log("s响应状态：" + xhr2.readyState);
//0: 请求未初始化，2 请求已接收，3 请求处理中，4 请求已完成，且响应已就绪
if (xhr2.readyState > 2) {
//这儿可以使用response(对应json)与responseText（对应text）
var newData1 = xhr2.response.substr(xhr2.seenBytes);
newData1 = newData1.replace(/\n/g, "#");
newData1 = newData1.substring(0, newData1.length - 1);
var data1 = newData1.split("#");
console.log("获取到的数据：" + data1);
document.getElementById("data").innerHTML = data1;
//长度重新赋值,下次截取时需要使用
xhr2.seenBytes = xhr2.response.length;
}
}
}
</script>
</body>
</html>
- demo2 订阅服务器消息，服务器send推送消息完成后，关闭sse.close
1.接口方法以及工具类
@GetMapping(path = "/sse/sub",produces = MediaType.TEXT_EVENT_STREAM_VALUE )
public SseEmitter subscribe(@RequestParam String questionId,HttpServletResponse response) {
// 简单异步发消息 ====
//questionId 订阅id，id对应了sse对象
new Thread(() -> {
try {
Thread.sleep(1000);
for (int i = 0; i < 10; i++) {
Thread.sleep(500);
SSEUtils.pubMsg(questionId, questionId + " - kingtao come " + i);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
// 消息发送完关闭订阅
SSEUtils.closeSub(questionId);
}
}).start();
// =================
return SSEUtils.addSub(questionId);
}
工具类
import org.springframework.web.servlet.mvc.method.annotation.SseEmitter;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
public class SSEUtils {
// timeout
private static Long DEFAULT_TIME_OUT = 2*60*1000L;
// 订阅表
private static Map<String, SseEmitter> subscribeMap = new ConcurrentHashMap<>();
/** 添加订阅 */
public static SseEmitter addSub(String questionId) {
if (null == questionId || "".equals(questionId)) {
return null;
}
SseEmitter emitter = subscribeMap.get(questionId);
if (null == emitter) {
emitter = new SseEmitter(DEFAULT_TIME_OUT);
subscribeMap.put(questionId, emitter);
}
return emitter;
}
/** 发消息 */
public static void pubMsg(String questionId, String msg) {
SseEmitter emitter = subscribeMap.get(questionId);
if (null != emitter) {
try {
// 更规范的消息结构看源码
emitter.send(SseEmitter.event().data(msg));
} catch (Exception e) {
// e.printStackTrace();
}
}
}
/**
* 关闭订阅
* @param questionId
*/
public static void closeSub(String questionId) {
SseEmitter emitter = subscribeMap.get(questionId);
if (null != emitter) {
try {
emitter.complete();
subscribeMap.remove(questionId);
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
2.前端代码
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>sse</title>
</head>
<body>
<div>
<label>问题id</label>
<input type="text" id="questionId">
<button onclick="subscribe()">订阅</button>
<hr>
<label>F12-console控制台查看消息</label>
</div>
<script>
function subscribe() {
let questionId = document.getElementById('questionId').value;
let url = 'http://localhost:9000/api/admin/test/sse/sub?questionId=' + questionId;
let eventSource = new EventSource(url);
eventSource.onmessage = function (e) {
console.log(e.data);
};
eventSource.onopen = function (e) {
console.log(e,1);
// todo
};
eventSource.onerror = function (e) {
// todo
console.log(e,2);
eventSource.close()
};
}
</script>
</body>
</html>