对于android原生模块[react-native]， nativemodule为null &g

Question

我正在尝试创建一个本地android模块来创建后台任务。我尝试遵循这个教程:https://blog.logrocket.com/run-react-native-background-tasks-headless-js/

但是当我尝试像这样调用我的模块时:

NativeModules.BackgroundWorkManager.startBackgroundWork();

我得到"无法读取null"属性' startbackfoundations '。那么为什么我的导入native模块是空的?:

import {NativeModules} from 'react-native';

My js file:

import React, { useEffect, useContext, useState } from 'react';
import { Text, View, ImageBackground, StyleSheet, FlatList, Image, TouchableOpacity } from 'react-native';
import GeolocationSvc from '../Services/GeolocationSvc';
import Geolocation from 'react-native-geolocation-service';
import {AppContext} from '../Providers/AppProvider';
import {calculateDistance} from '../Utiles';
import { useNavigation } from '@react-navigation/native';
import {NativeModules} from 'react-native';
const PlaceItem = ({data}) =>{
const [state, dispatch] = useContext(AppContext);
const [distance, setDistance] = useState(null);
const navigation = useNavigation();
const onPress = (id) => {
NativeModules.BackgroundWorkManager.startBackgroundWork();
navigation.navigate('SinglePlaceScreen', {placeId: id});
}

...
return (
...
)
}
...

我在MainApplication.java

中声明了这个

@Override
protected List<ReactPackage> getPackages() {
@SuppressWarnings("UnnecessaryLocalVariable")
List<ReactPackage> packages = new PackageList(this).getPackages();

packages.add(new BackgroundPackage());


return packages;
}

BackgroundPackage.java

package com.mystere;
import com.facebook.react.ReactPackage;
import com.facebook.react.bridge.NativeModule;
import com.facebook.react.bridge.ReactApplicationContext;
import com.facebook.react.uimanager.ViewManager;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
public class BackgroundPackage implements ReactPackage {
@Nonnull
@Override
public List<NativeModule> createNativeModules(@Nonnull ReactApplicationContext reactContext) {
List<NativeModule> modules = new ArrayList<>();
modules.add(new BackgroundModule(reactContext));
return modules;
}
@Nonnull
@Override
public List<ViewManager> createViewManagers(@Nonnull ReactApplicationContext reactContext) {
return Collections.emptyList();
}

}

My BackgroundModules.java:

package com.mystere;
import com.facebook.react.bridge.NativeModule;
import com.facebook.react.bridge.ReactApplicationContext;
import com.facebook.react.bridge.ReactContext;
import com.facebook.react.bridge.ReactContextBaseJavaModule;
import com.facebook.react.bridge.ReactMethod;
import java.util.Map;
import java.util.HashMap;
public class BackgroundModule extends ReactContextBaseJavaModule {
private static final String MODULE_NAME = "BackgroundWorkManager";
private Context mContext;
private PeriodicWorkRequest workRequest;
BackgroundModule(@Nonnull ReactApplicationContext reactContext) {
super(reactContext);
mContext = reactContext;
workRequest = new PeriodicWorkRequest.Builder(BackgroundWorker.class, 20, TimeUnit.MINUTES).build();
}
@ReactMethod
public void startBackgroundWork() {
WorkManager.getInstance(mContext).enqueueUniquePeriodicWork("testWork", ExistingPeriodicWorkPolicy.KEEP,workRequest);
}
@ReactMethod
public void stopBackgroundWork() {
WorkManager.getInstance(mContext).cancelUniqueWork("testWork");
}
@Nonnull
@Override
public String getName() {
return MODULE_NAME;
}
}

我MainApplication.java

package com.mystere;
import android.app.Application;
import android.content.Context;
import com.facebook.react.PackageList;
import com.facebook.react.ReactApplication;
import com.facebook.react.ReactInstanceManager;
import com.facebook.react.ReactNativeHost;
import com.facebook.react.ReactPackage;
import com.facebook.soloader.SoLoader;
import java.lang.reflect.InvocationTargetException;
import java.util.List;
import com.facebook.react.bridge.JSIModulePackage;
import com.swmansion.reanimated.ReanimatedJSIModulePackage;
import com.mystere.BackgroundPackage;
public class MainApplication extends Application implements ReactApplication {
private final ReactNativeHost mReactNativeHost =
new ReactNativeHost(this) {
@Override
public boolean getUseDeveloperSupport() {
return BuildConfig.DEBUG;
}
@Override
protected List<ReactPackage> getPackages() {
@SuppressWarnings("UnnecessaryLocalVariable")
List<ReactPackage> packages = new PackageList(this).getPackages();
// Packages that cannot be autolinked yet can be added manually here, for example:
packages.add(new BackgroundPackage());


return packages;
}
@Override
protected String getJSMainModuleName() {
return "index";
}
@Override 
protected JSIModulePackage getJSIModulePackage() { 
return new ReanimatedJSIModulePackage(); 
}

};
@Override
public ReactNativeHost getReactNativeHost() {
return mReactNativeHost;
}
@Override
public void onCreate() {
super.onCreate();
SoLoader.init(this, /* native exopackage */ false);
initializeFlipper(this, getReactNativeHost().getReactInstanceManager());

}
/**
* Loads Flipper in React Native templates. Call this in the onCreate method with something like
* initializeFlipper(this, getReactNativeHost().getReactInstanceManager());
*
* @param context
* @param reactInstanceManager
*/
private static void initializeFlipper(
Context context, ReactInstanceManager reactInstanceManager) {
if (BuildConfig.DEBUG) {
try {
/*
We use reflection here to pick up the class that initializes Flipper,
since Flipper library is not available in release mode
*/
Class<?> aClass = Class.forName("com.mystere.ReactNativeFlipper");
aClass
.getMethod("initializeFlipper", Context.class, ReactInstanceManager.class)
.invoke(null, context, reactInstanceManager);
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (NoSuchMethodException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
}
}
}

谢谢!

Answer 1

确保你的BackgroundModule.java:

@Override
public String getName() {
return "BackgroundWorkManager";
}