eventSource简单介绍
eventSource是用来解决web上服务器端向客户端推送消息的问题的。不同于ajax轮询的复杂和websocket的资源占用过大，eventSource(sse)是一个轻量级的，易使用的消息推送api
如何使用
客户端代码
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
</head>
<body>
<script type="text/javascript">
(function() {
var source = new EventSource('/stream')
source.onopen = function(event) {
console.log(event)
}
source.onmessage = function(event) {
console.log(event)
}
source.onerror = function(error) {
console.log(error)
}
})()
</script>
</body>
</html>代码很简单，实例化api，监听事件
服务端nodejs代码
服务端这几种实现使用其一就可以了
var http = require("http")
var fs = require('fs')
http.createServer(function (req, res) {
var fileName = "." + req.url;
if (fileName === "./stream") {
res.writeHead(200, {
"Content-Type":"text/event-stream",
"Cache-Control":"no-cache",
"Connection":"keep-alive"
});
res.write("retry: 10000\n");
res.write("event: connecttime\n");
res.write("data: " + (new Date()) + "\n\n");
res.write("data: " + (new Date()) + "\n\n");
interval = setInterval(function() {
res.write("data: " + (new Date()) + "\n\n");
}, 1000);
req.connection.addListener("close", function () {
clearInterval(interval);
}, false);
} else {
fs.readFile('./index.html', 'utf8',function(err, html) {
if (err) {
console.log(err)
return
}
res.end(html)
})
}
}).listen(9999);服务端expressjs代码
var express = require('express')
var fs = require('fs')
var app = express()
app.get('/stream', function(req, res) {
console.log(111)
res.writeHead(200, {
"Content-Type":"text/event-stream",
"Cache-Control":"no-cache",
"Connection":"keep-alive"
});
res.write("retry: 10000\n");
res.write("event: connecttime\n");
res.write("data: " + (new Date()) + "\n\n");
res.write("data: " + (new Date()) + "\n\n");
interval = setInterval(function() {
res.write("data: " + (new Date()) + "\n\n");
}, 1000);
req.connection.addListener("close", function () {
clearInterval(interval);
}, false);
})
app.use(function(req, res) {
fs.readFile('./index.html', 'utf8',function(err, html) {
if (err) {
console.log(err)
return
}
res.send(html)
})
})
app.listen(9999, function(err) {
if (err) {
console.log(err)
return
}
console.log('listening on port 9999')
})服务端koajs 1.x 代码
var koa = require('koa')
var fs = require('fs')
var PassThrough = require('stream').PassThrough
var app = koa()
app.use(function *() {
var url = this.req.url
if (url === '/stream') {
var stream = new PassThrough()
setInterval(function() {
stream.write("data: " + (new Date()) + "\n\n")
}, 1000);
this.type = 'text/event-stream'
this.body = stream
} else {
var html = yield koaFs
this.body = html
}
})
app.listen(9999, function(err) {
if (err) {
console.log(err)
return
}
console.log('listening on port 9999')
})
function koaFs(fn) {
fs.readFile('./index.html', 'utf8', function(err, html) {
fn(err, html)
})
}使用起来没什么问题，都可以正常运行，不过在多个客户端访问的时候，一个客户端连上之后，其他客户端就没有推送了，不知道为甚么？
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