javascript - 使用带有非常简单脚本的 Node 发送后无法设置 header

Question

我在 Node 中编写了一个相当复杂且有效的 js 脚本。我升级了我的服务器，发现它失败了。回到基础知识，我发现当我转到 http://www.mapworldlive.com:8899/test 时，这个简单的脚本失败并显示控制台消息，如下所示。从我的浏览器:

var http = require("http");
var express = require('express')
var app = express()
var server = http.createServer(app);
server.on('request', app);
server.listen(8899);
var chttime=new Date(),showdate=chttime.toDateString(),secs=chttime.getSeconds(),mins=chttime.getMinutes(),hrs=chttime.getHours(),day=chttime.getDay(),month=chttime.getMonth(),year=chttime.getFullYear();
console.log("Test Server started: "+hrs+":"+mins+" "+showdate);

app.use('/test',function(req, res) {
   console.log("hello world")
   res.end()
})

回应:

Test Server started: 14:23 Sat Feb 04 2017
hello world
Error: Can't set headers after they are sent.

请帮助我，以便其他人在我的情况下也能得到帮助!

堆栈跟踪:

Error: Can't set headers after they are sent.
    at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:356:11)
    at expressInit (/var/www/vhosts/mapworldlive.com/dev.mapworldlive.com/node_modules/express/lib/
iddleware/init.js:23:42)
    at Layer.handle [as handle_request] (/var/www/vhosts/mapworldlive.com/dev.mapworldlive.com/node
modules/express/lib/router/layer.js:95:5)
    at trim_prefix (/var/www/vhosts/mapworldlive.com/dev.mapworldlive.com/node_modules/express/lib/
outer/index.js:312:13)
    at /var/www/vhosts/mapworldlive.com/dev.mapworldlive.com/node_modules/express/lib/router/index.
s:280:7
    at Function.process_params (/var/www/vhosts/mapworldlive.com/dev.mapworldlive.com/node_modules/
xpress/lib/router/index.js:330:12)
    at next (/var/www/vhosts/mapworldlive.com/dev.mapworldlive.com/node_modules/express/lib/router/
ndex.js:271:10)
    at query (/var/www/vhosts/mapworldlive.com/dev.mapworldlive.com/node_modules/express/lib/middle
are/query.js:44:5)
    at Layer.handle [as handle_request] (/var/www/vhosts/mapworldlive.com/dev.mapworldlive.com/node
modules/express/lib/router/layer.js:95:5)
    at trim_prefix (/var/www/vhosts/mapworldlive.com/dev.mapworldlive.com/node_modules/express/lib/
outer/index.js:312:13)

Answer 1

这两行基本相同:

var server = http.createServer(app);

server.on('request', app);

所以我的猜测是您运行了两次请求处理，第二次发现第一个已经调用了 response.end。

删除 server.on 并重试。还有一个个人提示:不要调用 res.end，而是向浏览器输出一些内容，以便您可以轻松测试，例如 res.send('Hi!')。