获取请求在iOS上显示响应，但不适用于android

Question

我正在尝试使用React-Native（对于客户端）和Node / Express（对于服务器），从获取请求中发送响应。不幸的是，该值仅与iOS模拟器一起显示，而与android不一起显示。我在github https://github.com/facebook/react-native/issues/24627上遇到了一篇文章，建议在AndroidManifest文件上添加一些代码，但仍然无法正常工作，我尝试使用API​​ 25至29的设备，但均无法使用。有人可以帮忙吗？谢谢您的时间。

前端

import React, { Component } from "react";
import {Modal, StyleSheet, View, StatusBar, Text} from 'react-native'
import { Provider } from 'mobx-react';
import StateStorage from './StateStorage';


export default class App extends React.Component {

  constructor (props) {
    super(props)
    this.state ={

      data:''

    }
  }
  componentDidMount(){
    this.callBackendAPI()
    .then(res => this.setState({ data: res.express }))
    .catch(err => console.log(err));
  }
  callBackendAPI = async () => {
    const response = await fetch('http://localhost:5000');
    const body = await response.json();

    if (response.status !== 200) {
      throw Error(body.message) 
    }
    return body;
  };
  render() {
    return (
      <Provider store={StateStorage}>

<Text style={{top:100}}>{this.state.data}</Text>
        </Provider >
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',

  },

});

后端

const express = require('express')
const app = express()
const port = process.env.PORT || 5000;

app.get('/', (req, res) => {
    res.send({ express: 'YOUR EXPRESS BACKEND IS CONNECTED TO REACT' })
}
)





app.listen(port, () => console.log(`Example app listening on port ${port}!`))

AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
  package="com.mapp">

    <uses-permission android:name="android.permission.INTERNET" />

    <application
      android:name=".MainApplication"
      android:label="@string/app_name"
      android:icon="@mipmap/ic_launcher"
      android:roundIcon="@mipmap/ic_launcher_round"
      android:allowBackup="false"
      android:usesCleartextTraffic="true"
      tools:targetApi="28"
      android:theme="@style/AppTheme">
      <activity
        android:name=".MainActivity"
        android:label="@string/app_name"
        android:configChanges="keyboard|keyboardHidden|orientation|screenSize"
        android:windowSoftInputMode="adjustResize">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
      </activity>
      <activity android:name="com.facebook.react.devsupport.DevSettingsActivity" />
       <meta-data
     android:name="com.google.android.geo.API_KEY"
     android:value="AIzaSyD4Js3-PNHs1aL4XEmw6mAomblC2b4ys5s"/>
    </application>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>

Answer 1

默认情况下，从API 28开始，未加密的HTTP请求被阻止。

如果要启用它们，请切换到HTTPS或查看this answer。