javascript - 在 React Native 中授予权限

Question

我有一个项目，它使用 React Native Camera 库以及来自 vanilla React Native 的 CameraRoll。当我打开应用程序时，应用程序请求相机权限，但我不知道为什么。这仅仅是因为我在我的 AndroidManifest.xml 中指定了它吗？

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

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

    <application
      android:name=".MainApplication"
      android:label="@string/app_name"
      android:icon="@mipmap/ic_launcher"
      android:roundIcon="@mipmap/ic_launcher_round"
      android:allowBackup="false"
      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" />
    </application>

</manifest>

为什么在使用 React Native Camera 时我不必请求权限，但在使用 CameraRoll 时默认情况下不授予权限，我必须使用 React Native Permissions 库。

我问这个是因为我想在用户打开应用程序时立即请求所有这些权限，而且很难实现，因为我不知道在哪里请求权限。现在，用户“默认”会收到对相机的请求，但不会收到对存储的请求。这是为什么？

import React, {Component} from 'react';
import {StyleSheet, View} from 'react-native'
import { RNCamera } from 'react-native-camera'
import { CameraRoll } from 'react-native'
import Permissions from 'react-native-permissions'
import ActionButton from 'react-native-action-button'
import Icon from 'react-native-vector-icons/Ionicons'

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

  button: {
    height: 200,

    justifyContent: 'flex-end',
    alignItems: 'center'
  },

  actionButtonIcon: {
    fontSize: 20,
    height: 22,
    color: 'white',
  },

});


export default class Cam extends Component {
  constructor() {
    super()
    this.takePicture = this.takePicture.bind(this)

  }

  takePicture = async function() {
    if (this.camera) {
      const options = { quality: 0.5, base64: true }
      const data = await this.camera.takePictureAsync(options)
      CameraRoll.saveToCameraRoll(data.uri)
    }
  }

  render() {
    return (
      <View style={styles.container}>

        <RNCamera
          ref={ref => {this.camera = ref}}
          style={{
            flex: 1,
            width: '100%',
            position: 'relative'
          }}
        >
        </RNCamera>

        <ActionButton size={80} useNativeFeedback={false} buttonColor="rgba(231,76,60,1)">
          <ActionButton.Item useNativeFeedback={false} buttonColor='#9b59b6' title="Settings" onPress={this.props.switchScreen}>
            <Icon name="md-create" style={styles.actionButtonIcon} />
          </ActionButton.Item>
          <ActionButton.Item useNativeFeedback={false} buttonColor='#1abc9c' title="Start" onPress={this.takePicture}>
            <Icon name="md-done-all" style={styles.actionButtonIcon} />
          </ActionButton.Item>

        </ActionButton>

      </View>
    )
  }
}

Answer 1

这是因为你在 render 方法中调用了 react native camera :

        <RNCamera
          ref={ref => {this.camera = ref}}
          style={{
            flex: 1,
            width: '100%',
            position: 'relative'
          }}
        >
        </RNCamera>

为了解决这个问题，我使用了三元运算符和状态:

import React, { Component } from 'react';
import { StyleSheet, View } from 'react-native';
import { RNCamera } from 'react-native-camera';
import { CameraRoll } from 'react-native';
import Permissions from 'react-native-permissions';
import ActionButton from 'react-native-action-button';
import Icon from 'react-native-vector-icons/Ionicons';

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

  button: {
    height: 200,

    justifyContent: 'flex-end',
    alignItems: 'center'
  },

  actionButtonIcon: {
    fontSize: 20,
    height: 22,
    color: 'white'
  }
});

export default class Cam extends Component {
  constructor(props) {
    super(props);
    this.state = {
      takePicture: false
    };
  }

  takePicture = async () => {
    console.log('function was called');
    await this.setState({ takePicture: true });
    // if (this.camera) {
    //   const options = { quality: 0.5, base64: true };
    //   const data = await this.camera.takePictureAsync(options);
    //   CameraRoll.saveToCameraRoll(data.uri);
    // }
  };

  render() {
    return (
      <View style={styles.container}>
        {this.state.takePicture ? (
          <RNCamera
            ref={ref => {
              this.camera = ref;
            }}
            style={{
              flex: 1,
              width: '100%',
              position: 'relative'
            }}
          />
        ) : null}

        <ActionButton size={80} useNativeFeedback={false} buttonColor="rgba(231,76,60,1)">
          <ActionButton.Item useNativeFeedback={false} buttonColor="#9b59b6" title="Settings">
            <Icon name="md-create" style={styles.actionButtonIcon} />
          </ActionButton.Item>
          <ActionButton.Item useNativeFeedback={false} buttonColor="#1abc9c" title="Start" onPress={this.takePicture}>
            <Icon name="md-done-all" style={styles.actionButtonIcon} />
          </ActionButton.Item>
        </ActionButton>
      </View>
    );
  }
}

同样对于存储，不需要请求权限，只需要在Android xml文件中写上存储权限即可。 React native camera 和 Camera roll 以不同的方式请求许可是因为它们只制作了这样的库。如果您想在开始时同时询问所有权限，那么您可以使用 react native 权限并在开始时获得您想要的所有权限(如果有的话，可能在启动画面组件中)。然后当您稍后使用 React Native 相机时，它不会再次请求权限。