Post Request net::ERR_CONNECTION_REFUSED

Question

我正在构建React/Redux/Node应用程序，该应用程序将Spotify的API与授权代码流结合起来。这是一个带有React-Router的SPA，它有三条路由:Login, Timeline和Results。当从时间轴遍历到结果时，我得到这个错误:

POST http://localhost:3001/login net::ERR_CONNECTION_REFUSED

这是Github的repo。

这是Chrome DevTools打开时的错误视频。

useAuth。JSX(自定义钩子)

import { useState, useEffect } from 'react'
import axios from 'axios'
const useAuth = (code) => {
const [accessToken, setAccessToken] = useState()
useEffect(() => {
axios.post('http://localhost:3001/login', {
code,
}).then(res => {
setAccessToken(res.data.accessToken)
window.history.pushState({}, null, '/')
}).catch((err) => {
console.log(err)
})
}, [code])
return accessToken
}
export default useAuth

server.js

require('dotenv').config()
const express = require('express');
const SpotifyWebApi = require('spotify-web-api-node');
const cors = require('cors')
const bodyParser = require('body-parser')
const app = express();
app.use(cors())
app.use(bodyParser.json())
app.post('/login', (req, res) => {
const code = req.body.code
const spotifyApi = new SpotifyWebApi({
redirectUri: process.env.REDIRECT_URI,
clientId: process.env.CLIENT_ID,
clientSecret: process.env.CLIENT_SECRET,
})
spotifyApi.authorizationCodeGrant(code).then(data => {
res.json({
accessToken: data.body.access_token,
refreshToken: data.body.refresh_token,
expiresIn: data.body.expires_in,
})
})
.catch(() => {
res.sendStatus(400)
})
})
app.listen(3001)

App.js

import {useState, useEffect} from 'react'
import { Login } from './Login'
import { Timeline } from './Timeline'
import { Results } from './Results'
import { BrowserRouter as Router, Routes, Route } from 'react-router-dom'
import './App.css'
const code = new URLSearchParams(window.location.search).get('code');
const App = () => {
const [composers, setComposers] = useState([]);
useEffect(() => {
const fetchComposers = async () => {
const response = await fetch('composers.json');
const data = await response.json();
const listofComposers = data.composers.map((composer) => composer)
setComposers(listofComposers);
}
fetchComposers();
}, []);
return (
<Router>
<Routes>
<Route path='/' element={<Login code={code} />} />
<Route path='/timeline' element={<Timeline composerData={composers} />} />
<Route path='/results' element={<Results code={code}  />} />
</Routes>
</Router>

);
}
export default App;

Results.jsx

export const Results = ({ code }) => {
const accessToken = useAuth(code)
console.log(accessToken)

当我console.log(accessToken)时，它返回undefined

Answer 1

连接被拒绝意味着你的应用程序没有在3001端口监听。Chrome正在尝试连接它，但是不能。

(发送TCP SYN包并遇到TCP RST，但这与您的问题无关)

试着改变你的app.listen，看看会发生什么:

server.listen(3001, 'localhost'); // or server.listen(3001, '0.0.0.0'); for all interfaces
server.on('listening', function() {
console.log('Express server started on port %s at %s', server.address().port, server.address().address);
});

还有一个有趣的问题:你确定你运行了应用程序吗?特别是js文件server.js…

因为如果它不运行，它肯定不能监听任何端口，更不用说3001了。

验证它正在运行和在powershell中使用TCPView或get - netttcpconnection在正确的端口上侦听

Answer 2

看看这个答案是否有助于调试错误:

本质上就是catch(error =>)实际上就是catch(response =>)

Try toconsole.log(err.response.data)