Node.js Nodejs:Connect和";“书面标题”;在第一个连接回调中
在connect的第一次回调中调用“res.writeHead(…)”时,我始终收到错误“错误:发送头后无法设置头。”:Node.js Nodejs:Connect和";“书面标题”;在第一个连接回调中,node.js,connect,Node.js,Connect,在connect的第一次回调中调用“res.writeHead(…)”时,我始终收到错误“错误:发送头后无法设置头。”: var http = require('http'); var connect = require('connect'); var simpleApp = connect(); simpleApp .use(function(req, res, next){ res.writeHead(200, { 'content-type': 'text/h
var http = require('http');
var connect = require('connect');
var simpleApp = connect();
simpleApp
.use(function(req, res, next){
res.writeHead(200, { 'content-type': 'text/html' });
res.write('response powered by SIMPLE connect-object as middelware');
console.log('Pre');
next();
console.log('Post');
})
.use(function(req, res, next){
console.log('I am the header guy!');
next();
})
.use('/admin', function(req, res, next){
console.log('someone entered the admin area....');
next();
})
.use(function(req, res){
console.log('reached the tail of the "chain of responsibility!!!');
res.end();
});
http.createServer(simpleApp).listen(process.env.PORT || 3000);
console.log('Running on port "' + (process.env.PORT || 3000) + '"');
// just a save-guard to stop the process after some time...
setTimeout(function(){
process.exit(0);
}, 20000);
这是错误消息:
Error: Can't set headers after they are sent.
at ServerResponse.OutgoingMessage.setHeader (http.js:691:11)
at ServerResponse.res.setHeader (C:\Users\drt\SkyDrive\Programmierung\nodejs\silkveil\node_modules\connect\lib\patch.js:63:22)
at next (C:\Users\drt\SkyDrive\Programmierung\nodejs\silkveil\node_modules\connect\lib\proto.js:156:13)
at Object.handle (C:\Users\drt\SkyDrive\Programmierung\nodejs\silkveil\connectSampleApp.js:13:3)
at next (C:\Users\drt\SkyDrive\Programmierung\nodejs\silkveil\node_modules\connect\lib\proto.js:193:15)
at Function.app.handle (C:\Users\drt\SkyDrive\Programmierung\nodejs\silkveil\node_modules\connect\lib\proto.js:201:3)
at Server.app (C:\Users\drt\SkyDrive\Programmierung\nodejs\silkveil\node_modules\connect\lib\connect.js:65:37)
at Server.EventEmitter.emit (events.js:98:17)
at HTTPParser.parser.onIncoming (http.js:2108:12)
当我将“writeHead”代码移到最后一个回调中时,一切都很好:
.use(function(req, res){
console.log('reached the tail of the "chain of responsibility!!!');
res.writeHead(200, { 'content-type': 'text/html' });
res.write('response powered by SIMPLE connect-object as middelware');
res.end();
});
所以我的问题是:在使用connect时,是否只允许在最后一次回调中使用writeHead/write 您在代码的第一部分忘记了这一行:
res.end();
如果这不起作用,TJ Holowaychuk会在这里发表评论:
检查另一个问题。
基本上,在调用res.writeHead
后,无法再修改头,而next
方法将尝试修改头,这将导致异常
因此,您可以在第一次连接回调中修改标头,但不允许写入正文(res.write
)。下面的代码应该正常工作。简而言之,您可以修改标题,但不能刷新标题
var http = require('http');
var connect = require('connect');
var simpleApp = connect();
simpleApp
.use(function(req, res, next){
res.statusCode = 200;
res.setHeader( 'content-type', 'text/html' );
console.log('Pre');
next();
console.log('Post');
})
.use(function(req, res, next){
console.log('I am the header guy!');
next();
})
.use('/admin', function(req, res, next){
console.log('someone entered the admin area....');
next();
})
.use(function(req, res){
res.write('response powered by SIMPLE connect-object as middelware');
console.log('reached the tail of the "chain of responsibility!!!');
res.end();
});
http.createServer(simpleApp).listen(process.env.PORT || 3000);
console.log('Running on port "' + (process.env.PORT || 3000) + '"');
// just a save-guard to stop the process after some time...
setTimeout(function(){
process.exit(0);
}, 20000);
在最后一次连接回调中调用“res.end()”。我的想法是,我在不同的回调中写入响应,然后在最后一次回调中结束响应,我不理解您链接中的注释。。。为什么使用“书面头”不是一个好主意?我对node.js很陌生,所以请耐心听我说,所以在最后一次回调中只“允许”调用“res.write”!?因为我能够在第一次回调中使用“res.setHeader('content-type','text/html');”,并且它正在工作。对,您必须在最后一次回调之前将响应保留在Head部分。谢谢您的回答