node + express + mongodb 的问题，能收到请求，但是不能做出相应页面。不知道怎么解决~求大神帮忙，急~~~

Question

node 报错信息如下：（         Error: Can't set headers after they are sent.    at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:357:11)    at ServerResponse.header (D:\Hexin\FrontEnd\movie\node_modules\express\lib\response.js:730:10)    at ServerResponse.send (D:\Hexin\FrontEnd\movie\node_modules\express\lib\response.js:170:12)    at done (D:\Hexin\FrontEnd\movie\node_modules\express\lib\response.js:967:10)    at Object.exports.renderFile (D:\Hexin\FrontEnd\movie\node_modules\pug\lib\index.js:422:12)    at View.exports.__express [as engine] (D:\Hexin\FrontEnd\movie\node_modules\pug\lib\index.js:465:11)    at View.render (D:\Hexin\FrontEnd\movie\node_modules\express\lib\view.js:128:8)    at tryRender (D:\Hexin\FrontEnd\movie\node_modules\express\lib\application.js:640:10)    at EventEmitter.render (D:\Hexin\FrontEnd\movie\node_modules\express\lib\application.js:592:3)    at ServerResponse.render (D:\Hexin\FrontEnd\movie\node_modules\express\lib\response.js:971:7)    at D:\Hexin\FrontEnd\movie\app.js:90:9    at Layer.handle [as handle_request] (D:\Hexin\FrontEnd\movie\node_modules\express\lib\router\layer.js:95:5)    at next (D:\Hexin\FrontEnd\movie\node_modules\express\lib\router\route.js:137:13)    at Route.dispatch (D:\Hexin\FrontEnd\movie\node_modules\express\lib\router\route.js:112:3)    at Layer.handle [as handle_request] (D:\Hexin\FrontEnd\movie\node_modules\express\lib\router\layer.js:95:5)    at D:\Hexin\FrontEnd\movie\node_modules\express\lib\router\index.js:281:22GET / 404 76.603 ms - 645浏览器报错：路由：控制：(    

Answer 1

你的express.js有问题。引入router的位置。必须放在错误处理之前，也就是说 ：

app.use(bodyParser.urlencoded({extended: false}));    

require('../app/routes/news.server.routes')(app);    

app.use(function(req, res, next) {    

res.status(404);    

try {    

return res.json('NOT FOUND');    

} catch (e) {    

console.error('404 set header after sent');    

}    

});    

app.use(function(err, req, res, next) {    

if (!err) {    

next()    

} else {    

res.status(500);    

try {    

return res.json(err.message || '500 SERVER ERROR');    

} catch (e) {    

console.error('500 set header after sent');    

}    

}    

});    

看见加粗的了吗？后面两个错误处理必须放在最后，因为路由匹配规则是从上到下，匹配到了就终止！