錯誤
Fehler: Header k?nnen nach dem Senden nicht festgelegt werden.
at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:357:11)
at ServerResponse.header (D:\node\javascript-demo\node_modules\express\lib\response.js:730:10)
at ServerResponse.send (D:\node\javascript-demo\node_modules\express\lib\response.js:170:12)
at Timeout.setInterval [as _onTimeout] (D:\node\javascript-demo\routes\eventsource\eventsource.js:8:8)
at ontimeout (timers.js:384:18)
at tryOnTimeout (timers.js:244:5)
at Timer.listOnTimeout (timers.js:214:5) Program node --debug ./bin/www exited with code 1
const express = require('express');
const router = express.Router();
router.get('/connect',function(req,resp,next){
resp.append('Content-Type','text/event-stream');
console.log(req.method);
setInterval((data)=>{
resp.send('hello!');
},1000,'hello');
});
router.get('/html',(req,resp,next)=>{
resp.render('./eventsource/msgsend_recevie.html');
});module.exports=router;
<!DOCTYPE html>
<html lang="en">
<head>
<title>EventSource消息發(fā)送</title>
<style type="text/css">
*{
margin:0 auto;
padding:0;
}
p{
width:440px;
height:450px;
border:2px solid;
margin-top:100px;
}
</style>
</head>
<body>
<p>
<textarea id="msg_recevie" rows="30" cols="60"></textarea>
</p>
<script>
//使用eventsource發(fā)送信息
var eventSource = new EventSource('/msg_send/connect');
eventSource.onmessage=function(e){
var tx=document.getElementsByTagName('textarea')[0];
tx.value=e.data;
};
</script>
</body>
</html>
問題已解決,需要給發(fā)送的數(shù)據(jù)加上"data:"前綴,"nn"后綴,即"data"+msg+"nn"
服務端代碼修改如下:
const express = require('express');
const router = express.Router();
router.get('/connect',function(req,resp,next){
resp.writeHead(200,{
"Content-Type":"text/event-stream",
"Cache-Control":"no-cache",
"Connection":"keep-alive"
});
setInterval(function(){
resp.write("data:"+Date.now()+"\n\n");
},1000);
});
router.get('/html',(req,resp,next)=>{
resp.render('./eventsource/msgsend_recevie.html');
});
module.exports=router;
在express的response已經(jīng)send后,response不允許再進行header等一系列的操作,setintval是一個定時器,你的邏輯方式?jīng)]有正確。
你的setintval第一次已經(jīng)把響應推送出去了,那么后面這個響應已經(jīng)不能繼續(xù)操作了,由于http是單向非雙向的,所以第二次是無效的操作
如果你希望客戶端能夠接受服務端得事件推送的話,我推薦使用socketio,或者使用ajax輪訓去處理。