前言

在上一篇文章 中我们详细讲解了用Leancloud实现iOS消息推送的流程，今天本文将继续讲解实现Android的消息推送。

接入Leancloud

在接入Leancloud之前，还是推荐先阅读Leancloud官方的 Android消息推送开发指南。

安装Leancloud SDK

SDK有多种安装方式，详情请参考Android SDK安装指南。我选择用Gradle安装，先在根目录下的build.gradle中添加Leancloud的maven仓库地址：

buildscript {
    repositories {
        jcenter()
        maven {
            url 'https://maven.google.com/'
            name 'Google'
        }

        maven {
            url "http://mvn.leancloud.cn/nexus/content/repositories/public"
        }
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.3.3'
    }
}

allprojects {
    repositories {
        mavenLocal()
        jcenter()
        maven {
            url "$rootDir/../node_modules/react-native/android"
        }
        maven {
            url 'https://maven.google.com/'
            name 'Google'
        }
        maven {
            url "http://mvn.leancloud.cn/nexus/content/repositories/public"
        }
    }
}

然后打开 app 目录下的 build.gradle 进行如下配置：

android {
    //为了解决部分第三方库重复打包了META-INF的问题
    packagingOptions{
        exclude 'META-INF/LICENSE.txt'
        exclude 'META-INF/NOTICE.txt'
    }
    lintOptions {
        abortOnError false
    }
    ...
}

...

dependencies {
    ...
    
    // LeanCloud 基础包
    compile ('cn.leancloud.android:avoscloud-sdk:v4.6.4')
    // 推送与实时聊天需要的包
    compile ('cn.leancloud.android:avoscloud-push:v4.6.4@aar'){transitive = true}
}

初始化Leancloud

我们需要在App创建后用Leancloud的AppId，AppKey进行初始化，修改MainApplication如下：

@Override
  public void onCreate() {
    super.onCreate();
    ...
    //初始化leancloud
    AVOSCloud.initialize(this,"ppdriT1clcnRoda0okCPaB48-gzGzoHsz","Qzarq5cMdWzAMjwDW4umWpBL");
  }

接下来，在AndroidManifest.xml中配置Leancloud SDK所需的权限以及消息推送所需的service和receiver：

...

<!-- 基础模块（必须加入以下声明）START -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.READ_PHONE_STATE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<!-- 基础模块 END -->

<application
  ...
  android:name=".MainApplication" >
  ...

  <!-- 实时通信模块、推送（均需要加入以下声明） START -->
  <!-- 实时通信模块、推送都要使用 PushService -->
  <service android:name="com.avos.avoscloud.PushService"/>
  <receiver android:name="com.avos.avoscloud.AVBroadcastReceiver">
    <intent-filter>
      <action android:name="android.intent.action.BOOT_COMPLETED"/>
      <action android:name="android.intent.action.USER_PRESENT"/>
      <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
    </intent-filter>
  </receiver>
  <!-- 实时通信模块、推送 END -->
</application>

到此，Leancloud SDK的接入完成，我们需要测试一下SDK能不能正常使用。我们在MainActivity.java的onCreate方法中添加代码看能不能保存数据到Leancloud数据库：

@Override
protected void onCreate(Bundle savedInstanceState) {
    ...
    // 测试 SDK 是否正常工作的代码
    AVObject testObject = new AVObject("TestObject");
    testObject.put("words","Hello World!");
    testObject.saveInBackground(new SaveCallback() {
        @Override
        public void done(AVException e) {
            if(e == null){
                Log.d("saved","success!");
            }
        }
    });

    ...
}

启动App，前往Leancloud控制台，查看数据库中是否多了一条TestObject的记录，如果有说明Leancloud SDK接入成功：

保存Installation

和iOS一样，Android也需要保存installation才能让Leancloud确定推送到哪些设备。但是比较坑的是：Leancloud官方提供的 leancloud-installation只能正确保存iOS设备的installation。 因此我们只能使用Android的SDK保存installation，而且我们最好把这个方法封装成一个native模块暴露给js调用，以方便在保存成功或失败后执行相应操作。

在com.leancloudpushdemo文件夹中创建PushModule.java，PushDemo继承于ReactContextBaseJavaModule并实现ActivityEventListener接口，添加如下代码：

package com.leancloudpushdemo;

import android.app.Activity;
import android.content.Intent;
import com.avos.avoscloud.AVException;
import com.avos.avoscloud.AVInstallation;
import com.avos.avoscloud.SaveCallback;
import com.facebook.react.bridge.ActivityEventListener;
import com.facebook.react.bridge.Callback;
import com.facebook.react.bridge.ReactApplicationContext;
import com.facebook.react.bridge.ReactContextBaseJavaModule;
import com.facebook.react.bridge.ReactMethod;

public class PushModule extends ReactContextBaseJavaModule implements ActivityEventListener {

    public PushModule(ReactApplicationContext reactContext) {
        super(reactContext);
    }
    
    @Override
    public String getName() {
        return "androidPushModule";
    }
    
    @Override
    public void onNewIntent(Intent intent) {}

    @Override
    public void onActivityResult(Activity activity, int requestCode, int resultCode, Intent data) {}

    /**
     * 保存installation
     */
    @ReactMethod
    public void saveInstaillation(final Callback resultCallback) {
        AVInstallation.getCurrentInstallation().saveInBackground(new SaveCallback() {
            public void done(AVException e) {
                if (e == null) {
                    // 保存成功
                    String installationId = AVInstallation.getCurrentInstallation().getInstallationId();
                    resultCallback.invoke(installationId);
                } else {
                    resultCallback.invoke();
                }
            }
        });
    }
}

接着在同一目录下面添加PushPackage.java用于注册PushModule模块，代码如下：

package com.leancloudpushdemo;

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 PushPackage implements ReactPackage {

    @Override
    public List<NativeModule> createNativeModules(ReactApplicationContext reactContext) {
        List<NativeModule> modules = new ArrayList<>();
        modules.add(new PushModule(reactContext));
        return modules;
    }

    @Override
    public List<ViewManager> createViewManagers(ReactApplicationContext reactContext) {
        return Collections.emptyList();
    }
}

然后，在MainApplication.java中的getPackages方法中增加PushPackage：

@Override
protected List<ReactPackage> getPackages() {
    return Arrays.<ReactPackage>asList(
            ...
            new PushPackage()
    );
}

接着，在我们的PushService.js中引入PushModule并保存installation：

...
import { NativeModules } from 'react-native';
const AndroidPush = NativeModules.androidPushModule;

...
class PushService {
    
    ...
    //Android
    _an_initPush = () => {
        this._an_saveInstallation();
    }

    _an_saveInstallation = () => {
        AndroidPush.saveInstaillation((installationId) => {
            if (installationId) {
                console.log('Android installation 保存成功！');
            }
        })
    }
    ...
}

最后，在App.js中执行Android的初始化：

componentDidMount() {
    if (Platform.OS === 'ios') {
        PushService._iOS_initPush();
    } else {
        PushService._an_initPush();
    }
    MessageBarManager.registerMessageBar(this.refs.alert);
}

重启App，前往Leancloud控制台中查看数据库中是否多了一条installation记录，如果有说明保存成功：

如果确认代码没问题，但是还是保存不成功，我建议：

1. 重启Android Studio
2. 重启React Native Packager
3. 重启电脑、手机。。
4. 如果还有问题，欢迎咨询我

实现系统推送

启动推送服务

首先调用Leancloud SDK启动推送服务：

PushService.setDefaultPushCallback(getReactApplicationContext(), PushHandlerActivity.class);

PushHandlerActivity为收到通知默认打开的activity，我们接下来实现。

PushHandlerActivity实现

该activity的定位为接收并初步解析通知数据。我们在com.leancloudpushdemo文件夹下添加PushHandlerActivity.java，内容如下：

package com.leancloudpushdemo;

import android.app.Activity;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Bundle;
import java.util.HashMap;
import java.util.Map;


public class PushHandlerActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        processPush();
        finish();
        if (!PushModule.isActive()) {  //todo：判断PushModule是否实例化
            relaunchActivity();
        }
    }

    private void processPush() {
        try {
            Intent intent = getIntent();
            String action = intent.getAction();
            String channel = intent.getExtras().getString("com.avos.avoscloud.Channel");
            String data = intent.getExtras().getString("com.avos.avoscloud.Data");
            Map<String, String> map = new HashMap<String, String>();
            map.put("action", action);
            map.put("channel", channel);
            map.put("data", data);
            PushModule.onReceive(map); //todo：处理通知
        } catch (Exception e) {
            PushModule.onError(e); // todo：处理错误
        }
    }

    private void relaunchActivity() {
        PackageManager pm = getPackageManager();
        Intent launchIntent = pm.getLaunchIntentForPackage(getApplicationContext().getPackageName());
        startActivity(launchIntent);
    }
}

别忘了在AndroidManifest.xml中加上该activity：

<activity android:name=".PushHandlerActivity"></activity>

主要处理逻辑实现

PushHandlerActivity代码中有三处todo是我们接下来要在PushModule中实现的逻辑。关于接收到通知后如何处理，我的思路是当native module收到通知时，通过RCTDeviceEventEmitter触发相应的Event，在js中监听这些Event并响应，修改PushModule如下：

public class PushModule extends ReactContextBaseJavaModule implements ActivityEventListener {

    private static PushModule singleton;
    private static String ON_RECEIVE = "leancloudPushOnReceive";
    private static String ON_ERROR = "leancloudPushOnError";
    
    public PushModule(ReactApplicationContext reactContext) {
        super(reactContext);
        singleton = this;
    }
    
    ...
    
    protected static boolean isActive() {
        return singleton != null;
    }
    
    private static WritableMap getWritableMap(Map<String, String> map) {
        WritableMap writableMap = Arguments.createMap();
        writableMap.putString("action", map.get("action"));
        writableMap.putString("channel", map.get("channel"));
        writableMap.putString("data", map.get("data"));
        return writableMap;
    }

    protected static void onReceive(Map<String, String> map) {
        if (singleton != null) {
            WritableMap pushNotification = getWritableMap(map);
            DeviceEventManagerModule.RCTDeviceEventEmitter emitter = singleton.getReactApplicationContext().getJSModule(DeviceEventManagerModule.RCTDeviceEventEmitter.class);
            emitter.emit(ON_RECEIVE, pushNotification);
        }
    }

    protected static void onError(Exception e) {
        if (singleton != null) {
            WritableMap error = Arguments.createMap();
            error.putString("message", e.getLocalizedMessage());
            DeviceEventManagerModule.RCTDeviceEventEmitter emitter = singleton.getReactApplicationContext().getJSModule(DeviceEventManagerModule.RCTDeviceEventEmitter.class);
            emitter.emit(ON_ERROR, error);
        }
    }

    @Override
    public Map<String, Object> getConstants() {
        final Map<String, Object> constants = new HashMap<>();
        constants.put("ON_RECEIVE", ON_RECEIVE);
        constants.put("ON_ERROR", ON_ERROR);
        return constants;
    }
    
    ...

最后，我们在PushService.js增加对消息通知相关事件的监听和处理的逻辑，我选择在保存installation成功后增加监听：

...

import { DeviceEventEmitter } from 'react-native';

...
class PushService {
    ...
    
    _an_saveInstallation = () => {
        AndroidPush.saveInstaillation((installationId, error) => {
            if (installationId) {
                DeviceEventEmitter.addListener(AndroidPush.ON_RECEIVE, (notification) => {
                    console.log('receive android notification');
                    this._an_onNotificationTapped(notification);
                });
                DeviceEventEmitter.addListener(AndroidPush.ON_ERROR, (res) => {
                    console.log('android notification error');
                    console.log(res);
                });
            } else {
                console.log(error);
            }
        })
    }

    _an_onNotificationTapped = (notification) => {
        Alert.alert('Android Notification Tapped');
    }
}
...

现在我们在Leancloud控制台发送一条通知，手机应该能收到消息：

当点击通知的时候，App打开并执行我们自定义的逻辑：

实现App打开状态下的推送

到目前为止，我们已经实现了系统级的推送，和iOS一样，我们希望Android App打开状态下也能弹出通知提醒。Leancloud提供了这样的可能，我们可以通过 自定义Receiver 来实现。

自定义Receiver

我们在com.leancloudpushdemo路径下添加CustomPushReceiver.java，代码如下：

package com.leancloudpushdemo;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONException;
import com.alibaba.fastjson.JSONObject;
import java.util.HashMap;
import java.util.Map;

public class CustomPushReceiver extends BroadcastReceiver {
    private static final String TAG = "CustomPushReceiver";
    private HandleMessage handleMessage;
    @Override
    public void onReceive(Context context, Intent intent) {
        try {
            String action = intent.getAction();
            String channel = intent.getExtras().getString("com.avos.avoscloud.Channel");
            //获取消息内容
            String data = intent.getExtras().getString("com.avos.avoscloud.Data");
            JSONObject jsonObject = JSON.parseObject(data);
            if (jsonObject != null) {
                Map<String, String> map = new HashMap<String, String>();
                map.put("action", action);
                map.put("channel", channel);
                map.put("data", data);
                PushModule.onCustomReceive(map); //todo: 处理通知
                if (handleMessage!=null){
                    handleMessage.receiveMessage(jsonObject);
                }
            }
        } catch (JSONException e) {
            PushModule.onError(e);
        }
    }

    interface HandleMessage{
        public void receiveMessage(JSONObject jsonObject);
    }

    public void setHandleMessage(HandleMessage handleMessage) {
        this.handleMessage = handleMessage;
    }
}

todo的方法待会儿在PushModule中实现。接着，在AndroidManifest.xml中添加custom receiver:

<receiver android:name="com.leancloudpushdemo.CustomPushReceiver">
    <intent-filter>
        <action android:name="com.cnuip.INNER_NOTI" />
    </intent-filter>
</receiver>

通知处理

然后修改PushModule如下：

public class PushModule extends ReactContextBaseJavaModule implements ActivityEventListener {
    ...
    private static String ON_CUSTOM_RECEIVE = "leancloudPushOnCustomReceive";
    
    ...
    
    protected static void onCustomReceive(Map<String, String> map) {
        if (singleton != null) {
            WritableMap pushNotification = getWritableMap(map);
            DeviceEventManagerModule.RCTDeviceEventEmitter emitter = singleton.getReactApplicationContext().getJSModule(DeviceEventManagerModule.RCTDeviceEventEmitter.class);
            emitter.emit(ON_CUSTOM_RECEIVE, pushNotification);
        }
    }

    ...
    
    @Override
    public Map<String, Object> getConstants() {
        final Map<String, Object> constants = new HashMap<>();
        constants.put("ON_RECEIVE", ON_RECEIVE);
        constants.put("ON_CUSTOM_RECEIVE", ON_CUSTOM_RECEIVE);
        constants.put("ON_ERROR", ON_ERROR);
        return constants;
    }
}

最后，修改PushService.js，增加对ON_CUSTOM_RECEIVE事件的监听：

...
_an_saveInstallation = () => {
    AndroidPush.saveInstaillation((installationId, error) => {
        if (installationId) {
            ...
            DeviceEventEmitter.addListener(AndroidPush.ON_CUSTOM_RECEIVE, (notification) => {
                console.log('receive custom android notification');
                this._showAlert(JSON.parse(notification.data).alert);
            });
            ...
        } else {
            ...
        }
    })
}
...

同时通知的消息提也需要做相应修改，才能让custom receiver接收到，我们可以用Postman来发送消息：

消息发出后，App中成功弹出消息提醒，完美。

结语

经过不懈的努力，我们已经成功使用Leancloud实现了iOS和Android上的消息通知，第一次写这么长的文章还是有点累的。。如果对你有帮助欢迎点赞！还有虽然功能都实现了，但是我想可能还会有更好的实现方式，欢迎找到的同学分享，谢谢！

相关链接

iOS篇地址：使用Leancloud实现React Native App的消息推送（Push Notification）- iOS篇

本文Demo Github地址：https://github.com/MudOnTire/LeancloudPushDemo)