Question

我在尝试读取文件并将响应发送回浏览器时遇到错误。

[ 'Error: Can\'t set headers after they are sent.',
  '    at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:344:11)',
  '    at ServerResponse.setWriteHeadHeaders (/somepath/node_modules/on-headers/index.js:82:19)',
  '    at ServerResponse.writeHead (/somepath/node_modules/on-headers/index.js:41:36)',
  '    at /somepath/server/custom.js:71:13',
  '    at FSReqWrap.readFileAfterClose [as oncomplete] (fs.js:380:3)' ]

＆＃13;

var fs = require('fs');

exports.customPageChatStatus = function(req, res) {
	if(req.params._pagename === 'Test123')
	{
    		fs.readFile("/somepath/Test123.txt", 'utf-8', function(err, data) {
	       if (err) console.log(err);
	       res.writeHead(200, {'Content-Type':'text/plain', 'Access-Control-Allow-Origin':'*' });
       	res.end(data);
    		});
	}
	if(req.params._pagename === 'SecondFile')
	{
    		fs.readFile("/somepath/SecondFile.txt", 'utf-8', function(err, data) {
	       if (err) console.log(err);
	       res.writeHead(200, {'Content-Type':'text/plain', 'Access-Control-Allow-Origin':'*' });
       	res.end(data);
    		});
	}
	else {
		fs.readFile("/somepath/InActive.txt", 'utf-8', function(err, data) {
	       res.writeHead(200, {'Content-Type':'text/plain', 'Access-Control-Allow-Origin':'*' });
       	res.end(data);
    		});
	}
};

＆＃13;

有趣的是，我只是在阅读第一个文件（Test123.txt）时才看到上述错误，在阅读＆＃34; SecondFile.txt＆＃34;时没有问题。

感谢您解决此问题的任何帮助！

Answer 1

此处如果您在声明中使用else，则会解决您的问题

var fs = require('fs');

    exports.customPageChatStatus = function(req, res) {
        if(req.params._pagename === 'Test123')
        {
                fs.readFile("/somepath/Test123.txt", 'utf-8', function(err, data) {
              if (err) console.log(err);
               res.writeHead(200, {'Content-Type':'text/plain', 'Access-Control-Allow-Origin':'*' });
            res.end(data);
                });
        }
        else if(req.params._pagename === 'SecondFile')
        {
                fs.readFile("/somepath/SecondFile.txt", 'utf-8', function(err, data) {
               if (err) console.log(err);
               res.writeHead(200, {'Content-Type':'text/plain', 'Access-Control-Allow-Origin':'*' });
            res.end(data);
                });
        }
        else {
            fs.readFile("/somepath/InActive.txt", 'utf-8', function(err, data) {
               res.writeHead(200, {'Content-Type':'text/plain', 'Access-Control-Allow-Origin':'*' });
            res.end(data);
                });
        }
    };

Answer 2

令人惊讶的是if..else if ..实际上是一个问题。我确定这两种情况永远不会成真。

我想到了一种更简洁的方法。

更简单的代码：

var fs = require('fs');

exports.customPageChatStatus = function(req, res) {
    let pagename = req.params.pagename;

    if (pagename !== 'Test123' || pagename !== 'Secondfile') pagename = 'InActive';

    fs.readFile(`/somepath/${pagename}.txt`, 'utf-8', function(err, data) {
    if (err) return console.log(err);
    res.writeHead(200, {'Content-Type':'text/plain', 'Access-Control-Allow-Origin':'*' });
    return res.end(data);
    });
};

错误：在阅读文件

2 个答案: