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Unity与Android交互通信系列（6）

news 来源：原创 2024/9/30 7:15:10

本节主要讲述广播订阅。

使用AndroidJavaProxy代理接口，我们可以很方便的实现对Android端事件的订阅，灵活的进行Android端与Unity端的代码交互。通过AndroidJavaProxy代理，我们也可以在安卓端使用 BroadcastReceiver 接收广播，然后利用自定义的方法传递给C#端，但这种方式不太通用，我们希望能直接在C#端注册Android广播，下面演示一个通用的广播接收器。

其原理依然是利用AndroidJavaProxy接口进行桥接，但通过Unity端注入action（Android端广播动作名称）参数，即由C#端控制需要注册的广播，Android端接收到广播之后，进行相应的数据处理（方便将这些数据传递到C#端），然后调用接口方法，触发C#端广播处理方法。首先我们看一下调用逻辑，代码如下：

//代码6-1
//C#端代码
using System.Collections.Generic;
using UnityEngine;
public class BroadcastExample : MonoBehaviour, UnityBroadcastHelper.IBroadcastListener
{UnityBroadcastHelper helper;void Start(){helper = UnityBroadcastHelper.Register( new string[] { "some_action_name" }, this);}public void OnReceive(string action, Dictionary<string, string> dictionary){//广播处理逻辑}void OnDisable(){helper.Stop();}
}

通过代码13-17可以看到广播注册界面非常简洁，脚本实现了UnityBroadcastHelper.IBroadcastListener 接口，在Start()方法中初始化一个UnityBroadcastHelper 对象，然后通过OnReceive()方法等待Android端回调并进行相应处理即可，使用完后，通过OnDisable()方法停止广播监听。

C#端UnityBroadcastHelper类代码如下：

//代码6－2
//C#端代码
using System.Collections.Generic;
using UnityEngine;
public class UnityBroadcastHelper
{//Java端对象private readonly AndroidJavaObject javaObject;//构建函数，生成唯一Java端对象实例private UnityBroadcastHelper(string[] actions, IBroadcastListener listener){ListenerAdapter adapter = new ListenerAdapter(listener, this);javaObject = new AndroidJavaObject("com.example.davidwang.UnityBroadcastHelper", actions, adapter);}//注册广播public static UnityBroadcastHelper Register(string[] actions, IBroadcastListener listener){return new UnityBroadcastHelper(actions, listener);}//取消广播订阅public void Stop(){javaObject.Call("stop");}//广播订阅者接口public interface IBroadcastListener{void OnReceive(string action, Dictionary<string, string> dictionary);}//AndroidJavaProxy实现桥接,处理数据并触发订阅方法private class ListenerAdapter : AndroidJavaProxy{readonly IBroadcastListener listener;readonly UnityBroadcastHelper helper;public ListenerAdapter(IBroadcastListener listener, UnityBroadcastHelper helper) : base("com.example.davidwang.UnityBroadcastHelper$BroadcastListener"){this.listener = listener;this.helper = helper;}void onReceive(string action){AndroidJavaObject javaObject = helper.javaObject;if (!javaObject.Call<bool>("hasKeyValue")){return;}string[] keys = javaObject.Call<string[]>("getKeys");string[] values = javaObject.Call<string[]>("getValues");javaObject.Call("pop");Dictionary<string, string> dictionary = new Dictionary<string, string>();int n = keys.Length;for (int i = 0; i < n; i++){dictionary[keys[i]] = values[i];}listener.OnReceive(action, dictionary);}}
}

UnityBroadcastHelper类是接口的辅助类，其内部定义了IBroadcastListener接口及桥接类ListenerAdapter，并定义了注册与取消注册方法，从而简化调用端的使用。

Java端代码如下：

//代码6-3
//Java端代码
package com.example.davidwang;import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import java.util.LinkedList;
import java.util.Queue;
//引入UnityPlayer类
import com.unity3d.player.UnityPlayer;public class UnityBroadcastHelper {private static final String TAG = "UnityBroadcastHelper";//接口定义public interface BroadcastListener {void onReceive(String action);}private final BroadcastListener listener;private Queue<String[]> keysQueue = new LinkedList<>();private Queue<String[]> valuesQueue = new LinkedList<>();//构造函数，注入Unity端广播订阅者并注册广播public UnityBroadcastHelper(String[] actions, BroadcastListener listener) {this.listener = listener;IntentFilter intentFilter = new IntentFilter();for (String action : actions) {intentFilter.addAction(action);}Context context = UnityPlayer.currentActivity;if (context == null) {return;}context.registerReceiver(broadcastReceiver, intentFilter);}public boolean hasKeyValue() {return !keysQueue.isEmpty();}//返回健public String[] getKeys() {return keysQueue.peek();}//返回值public String[] getValues() {return valuesQueue.peek();}public void pop() {keysQueue.poll();valuesQueue.poll();}//取消广播注册public void stop() {Context context = UnityPlayer.currentActivity;if (context == null) {return;}context.unregisterReceiver(broadcastReceiver);}//广播处理并回调Unity中OnReceive()方法private BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {@Overridepublic void onReceive(Context context, Intent intent) {String action = intent.getAction();MyLog.d(TAG, "UnityBroadcastHelper: action: " + action);Bundle bundle = intent.getExtras();if (bundle == null) {bundle = new Bundle();}int n = bundle.size();String[] keys = new String[n];String[] values = new String[n];int i = 0;for (String key : bundle.keySet()) {keys[i] = key;Object value = bundle.get(key);values[i] = value != null ? value.toString() : null;i++;}keysQueue.offer(keys);valuesQueue.offer(values);listener.onReceive(action);}};
}

UnityBroadcastHelper类中的BroadcastListener接口即为需要桥接的接口，在该类的构造函数中传入了C#端定义的action及桥接实例对象并进行了广播注册操作，在stop()方法中取消了广播注册，UnityBroadcastHelper通过持有BroadcastReceiver，将广播注册到Context上下文中。为在两端进行数据传递，将Extra的Bundle数据映射为C#中的Dictionary，传递给 OnReceive()方法，方便C#代码使用。为演示简单，这里将所有类型的数据都映射成string类型，实际使用时可根据需要进行处理，如通过AndroidJavaObject进行复杂类型数据传递。

通过使用该通用类，不仅可以注册自定义广播，也可以注册系统广播（可能需要权限申请），还可以一次性注册多个广播，界面简洁，使用简单。