Android通过RemoteViews实现跨进程更新UI

一、概述

前面一篇文章Android通过AIDL实现跨进程更新UI我们学习了aidl跨进程更新ui，这种传统方式实现跨进程更新UI是可行的，但有以下弊端：

• View中的方法数比较多，在IPC中需要增加对应的方法比较繁琐。
• View的每一个方法都会涉及到IPC操作，多次IPC带来的开销问题不容小觑。
• View中方法的某些参数可能不支持IPC传输。例如：OnClickListener，它仅仅是个接口没有序列化。

接下来我们通过RemoteViews实现跨进程更新UI

二、实现效果图

在同一个应用中有两个Activity，MainActivity和Temp2Activity，这两个Activity不在同一个进程中。

现在需要通过Temp2Activity来改变MainActivity中的视图，即在MainActivity中添加两个Button，也就是实现跨进程更新UI这么一个功能。

在MainActivity里点击“跳转到新进程ACTIVITY”按钮，会启动一个新进程的Temp2Activity，我们先点击“绑定服务”，这样我们就启动了服务，再点击“AIDL更新”按钮，通过调用handler来实现跨进程更新UI，点击返回，我们发现MainActivity页面中新添加了两个按钮，并且按钮还具有点击事件。

三、核心代码

IremoteViewsManager.aidl

// IremoteViewsManager.aidl.aidl
package com.czhappy.remoteviewdemo;

interface IremoteViewsManager {
    void addRemoteView(in RemoteViews remoteViews);
}

RemoteViewsAIDLService.java

package com.czhappy.remoteviewdemo.service;

import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.Bundle;
import android.os.IBinder;
import android.os.Message;
import android.os.RemoteException;
import android.widget.RemoteViews;

import com.czhappy.remoteviewdemo.IremoteViewsManager;
import com.czhappy.remoteviewdemo.activity.MainActivity;

/**
 * Description:
 * User: chenzheng
 * Date: 2017/2/10 0010
 * Time: 10:56
 */
public class RemoteViewsAIDLService extends Service {
    private static final String TAG = "RemoteViewsAIDLService";

    private Binder remoteViewsBinder = new IremoteViewsManager.Stub(){
        @Override
        public void addRemoteView(RemoteViews remoteViews) throws RemoteException {
            Message message = new Message();
            message.what = 1;
            Bundle bundle = new Bundle();
            bundle.putParcelable("remoteViews",remoteViews);
            message.setData(bundle);
            new MainActivity.MyHandler(RemoteViewsAIDLService.this,getMainLooper()).sendMessage(message);
        }
    };

    public RemoteViewsAIDLService() {

    }

    @Override
    public IBinder onBind(Intent intent) {
        return remoteViewsBinder;
    }

}

MainActivity.java

package com.czhappy.remoteviewdemo.activity;

import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.LinearLayout;
import android.widget.RemoteViews;
import android.widget.TextView;

import com.czhappy.remoteviewdemo.R;

import java.lang.ref.WeakReference;

public class MainActivity extends AppCompatActivity {

    private static String TAG = "MainActivity";
    private static LinearLayout mLinearLayout;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mLinearLayout = (LinearLayout) this.findViewById(R.id.mylayout);
    }

    public static class MyHandler extends Handler {
        WeakReference weakReference;
        public MyHandler(Context context, Looper looper) {
            super(looper);
            weakReference = new WeakReference<>(context);
        }
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            Log.i(TAG, "handleMessage");
            switch (msg.what) {
                case 1: //RemoteViews的AIDL实现
                    RemoteViews remoteViews = msg.getData().getParcelable("remoteViews");
                    if (remoteViews != null) {
                        Log.i(TAG, "updateUI");

                        View view = remoteViews.apply(weakReference.get(), mLinearLayout);
                        mLinearLayout.addView(view);
                    }
                    break;
                default:
                    break;
            }
        }

    };

    public void readyGo(View view){
        Intent intent = new Intent(MainActivity.this, Temp2Activity.class);
        startActivity(intent);
    }

}

Temp2Activity.java

package com.czhappy.remoteviewdemo.activity;

import android.app.PendingIntent;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.os.RemoteException;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.RemoteViews;

import com.czhappy.remoteviewdemo.IremoteViewsManager;
import com.czhappy.remoteviewdemo.R;
import com.czhappy.remoteviewdemo.service.RemoteViewsAIDLService;

/**
 * Description:
 * User: chenzheng
 * Date: 2017/2/9 0009
 * Time: 16:05
 */
public class Temp2Activity extends AppCompatActivity {

    private String TAG = "Temp2Activity";

    private IremoteViewsManager remoteViewsManager;
    private boolean isBind = false;


    private ServiceConnection remoteViewServiceConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            Log.i(TAG,"onServiceConnected");
            remoteViewsManager = IremoteViewsManager.Stub.asInterface(service);

        }

        @Override
        public void onServiceDisconnected(ComponentName name) {
            //回收
            remoteViewsManager = null;
        }
    };

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        this.setContentView(R.layout.activity_temp);
    }

    /**
     * 绑定服务
     */
    public void bindService(View view) {
        Intent viewServiceIntent = new Intent(this,RemoteViewsAIDLService.class);
        isBind = bindService(viewServiceIntent,remoteViewServiceConnection, Context.BIND_AUTO_CREATE);
    }

    /**
     * 更新UI
     */
    public void UpdateUI(View view){
        RemoteViews remoteViews = new RemoteViews(Temp2Activity.this.getPackageName(),R.layout.button_layout);

        Intent intentClick = new Intent(Temp2Activity.this,FirstActivity.class);
        PendingIntent openFirstActivity = PendingIntent.getActivity(Temp2Activity.this,0,intentClick,0);
        remoteViews.setOnClickPendingIntent(R.id.firstButton,openFirstActivity);

        Intent secondClick = new Intent(Temp2Activity.this,SecondActivity.class);
        PendingIntent openSecondActivity = PendingIntent.getActivity(Temp2Activity.this,0,secondClick,0);
        remoteViews.setOnClickPendingIntent(R.id.secondButton,openSecondActivity);

        remoteViews.setCharSequence(R.id.secondButton,"setText","想改就改");
        try {
            remoteViewsManager.addRemoteView(remoteViews);
        } catch (RemoteException e) {
            e.printStackTrace();
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if(isBind){
            unbindService(remoteViewServiceConnection);
            isBind = false;
        }

    }

}

AndroidManifest.xml

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

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".activity.MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            intent-filter>
        activity>
        <activity android:name=".activity.FirstActivity" />
        <activity android:name=".activity.SecondActivity" />
        <activity
            android:name=".activity.Temp2Activity"
            android:process=":remote2" />

        <service android:name="com.czhappy.remoteviewdemo.service.RemoteViewsAIDLService" />


    application>

manifest>

四、总结

RemoteViews就是为跨进程更新UI而生的，内部封装了很多方法用来实现跨进程更新UI。但这并不代表RemoteViews是就是万能的了，它也有不足之处，目前支持的布局和View有限
layout：
FrameLayout LinearLayout RelativeLayout GridLayout
View：
AnalogClock button Chronometer ImageButton ImageView ProgressBar TextView ViewFlipper ListView GridView StackView AdapterViewFlipper ViewStub

不支持自定义View 所以具体使用RemoteViews还是aidl或者BroadCastReceiver还得看实际的需求。