java - 如何在 React Native 中从 Java 代码访问 ReactContext？

Question

我试图创建一个应用程序，它会使用 BroadcastReciver 捕获手机的来电。从我的 BroadcastReciver 我想使用 this 将数字作为事件发送到我的 JS 文件方法。

我已经检查过我的 Java 代码是否正常工作并且正在捕获调用和号码，但是我的应用程序因提到 react 上下文为空的错误而崩溃。我猜这是因为当来自 android 系统的事件被捕获并且新实例没有 ReactContext 时， list (或其他东西)正在创建类的新实例。有什么方法可以从 Java 代码访问 ReactContext 或通过 list 将 ReactContext 发送到 BroadcastReciver？

这是我的广播接收者:

package com.bridgetest;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.telephony.PhoneStateListener;
import android.telephony.TelephonyManager;
import android.util.Log;

import com.facebook.react.modules.core.DeviceEventManagerModule;
import com.facebook.react.bridge.JavaScriptModule;


import android.widget.Toast;

import com.facebook.react.bridge.ReactApplicationContext;
import com.facebook.react.bridge.ReactContext;
import com.facebook.react.bridge.WritableMap;
import com.facebook.react.bridge.Arguments;

import javax.annotation.Nullable;

/**
 * Created by Erik on 2016-04-06. 
 */
public class BroadcastReceiverCustom extends BroadcastReceiver {

    ReactContext reactContext;

    public BroadcastReceiverCustom (){
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        if             (intent.getStringExtra(TelephonyManager.EXTRA_STATE).equals(TelephonyManager.EXTRA_STATE_RINGING)) {
            // This code will execute when the phone has an incoming call

            // get the phone number
            String incomingNumber =     intent.getStringExtra(TelephonyManager.EXTRA_INCOMING_NUMBER);
            Toast.makeText(context, "Call from:" +incomingNumber, Toast.LENGTH_LONG).show();
            sendCallEvent(incomingNumber);

        } else if (intent.getStringExtra(TelephonyManager.EXTRA_STATE).equals(
                TelephonyManager.EXTRA_STATE_IDLE)
                || intent.getStringExtra(TelephonyManager.EXTRA_STATE).equals(
                    TelephonyManager.EXTRA_STATE_OFFHOOK)) {
            // This code will execute when the call is disconnected
            Toast.makeText(context, "Detected call hangup event", Toast.LENGTH_LONG).show();
        }
    }

    public void sendCallEvent(String incomingNumber){
            WritableMap params = Arguments.createMap();
            params.putString("Number", incomingNumber);
            sendEvent("CallRecevied", params);
    }


    private void sendEvent(String eventName,
                          @Nullable WritableMap params) {
        reactContext
            .getJSModule(DeviceEventManagerModule.RCTDeviceEventEmitter.class)
            .emit(eventName, params);
    }
}

Answer 1

由于 Fury 的解决方案在广播接收器中对我不起作用(getApplication() 出现“找不到符号”)，我尝试应用类似的逻辑，我知道这是有效的。所以:

import com.facebook.react.modules.core.DeviceEventManagerModule;
import com.facebook.react.bridge.Arguments;
import com.facebook.react.ReactApplication;
...
// context - is the context you get from broadcastreceivers onReceive
ReactApplication rnApp = (ReactApplication) context.getApplicationContext();

rnApp.getReactNativeHost().getReactInstanceManager()
                                .getCurrentReactContext().getJSModule(DeviceEventManagerModule.RCTDeviceEventEmitter.class)
                                .emit("test", Arguments.createMap());

这对我有用。