安卓双进程保活的代码

　　首先要声明，双进程保活，不是为了解决被杀之后复活的问题。因为在新版本的安卓上，这个办法已经不灵了（也许有人有更好的办法？）。这里介绍这个双进程保活，是为在电视盒子上的应用。如果进程死了，有的系统会自动启动，有的就不会。而有的应用在电视盒子上必须常在线。

　　本文实现方法，与其他介绍的原理一样，代码更加精练。为什么呢？因为使用了继承。

　　首先写一个AIDL：

package com.csdn;

interface IKeepAliveServiceConnection
{
    String getProcessName();
}

然后写一个父类：

package com.keepalive;
import android.app.Service;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.IBinder;
import android.os.RemoteException;
import android.util.Log;

import com.newayte.nvideo.IKeepAliveServiceConnection;


public abstract class KeepAliveService extends Service
{
    private static final String TAG = KeepAliveService.class.getCanonicalName();

    private static final String KEEP_ALIVE = "keep-alive";


    private KeepAliveBinder mKeepAliveBinder;
    private KeepAliveServiceConnection mKeepAliveConnection;

    @Override
    public void onCreate()
    {
        super.onCreate();

        if (mKeepAliveBinder == null)
        {
            mKeepAliveBinder = new KeepAliveBinder();
            mKeepAliveConnection = new KeepAliveServiceConnection();
        }
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId)
    {
        bindService(getConnectionIntent(), mKeepAliveConnection, Context.BIND_IMPORTANT);

        Log.d(TAG, "onStartCommand()");
        /*PendingIntent contentIntent = PendingIntent.getService(this, 0, intent, 0);
        NotificationCompat.Builder builder = new NotificationCompat.Builder(this);
        builder.setTicker("CSDN")
                .setContentIntent(contentIntent)
                .setContentTitle("TITLE")
                .setAutoCancel(true)
                .setContentText("CONTENT")
                .setWhen( System.currentTimeMillis());

        //把service设置为前台运行
        startForeground(startId, builder.build());*/

        return START_STICKY;
    }

    @Override
    public IBinder onBind(Intent intent)
    {
        //子类如果跟其他进程绑定时，从父类得到的binder不为空，说明是从保活服务启动的。
        Log.d(TAG, KEEP_ALIVE+"="+intent.getBooleanExtra(KEEP_ALIVE, false)+", "+intent);
        if (intent.getBooleanExtra(KEEP_ALIVE, false))
        {
            return mKeepAliveBinder;
        }
        return null;
    }

    private Intent getConnectionIntent()
    {
        Intent intent = new Intent(KeepAliveService.this, getPeerService());
        intent.putExtra(KEEP_ALIVE, true);
        return intent;
    }

    class KeepAliveBinder extends IKeepAliveServiceConnection.Stub
    {
        @Override
        public String getProcessName() throws RemoteException
        {
            return getServiceName();
        }
    }

    class KeepAliveServiceConnection implements ServiceConnection
    {

        @Override
        public void onServiceConnected(ComponentName name, IBinder service)
        {
            Log.d(TAG, getPeerService().getCanonicalName()+"建立连接成功！");
        }

        @Override
        public void onServiceDisconnected(ComponentName name)
        {
            Log.d(TAG, getPeerService().getCanonicalName()+"服务进程已死。重新启动并建立链接。");
            //启动被干掉的
            KeepAliveService.this.startService(getConnectionIntent());
            KeepAliveService.this.bindService(getConnectionIntent(), mKeepAliveConnection, Context.BIND_IMPORTANT);
        }

    }

    /**
     * 这两个并不是必要的。
     * 考虑到子类，还是要有点代码的。
     *
     * @return
     */
    protected abstract String   getServiceName();

    protected abstract Class<?> getPeerService();

}

子类服务助手（怎么样？使用了继承，极为简单吧）：

package com.keepalive;

public class AssistantServiceTv extends KeepAliveService
{

    @Override
    protected String   getServiceName()
    {
        return AssistantServiceTv.class.getCanonicalName();
    }

    @Override
    protected Class<?> getPeerService()
    {
        return NetworkServiceTv.class;
    }

}

主服务（注意onBind()的代码）:

package com.keepalive;

public class NetworkServiceTv extends KeepAliveService
{
    @Override
    public IBinder onBind(Intent intent)
    {
        Log.d(TAG, "service onBind="+intent);
        IBinder binder = super.onBind(intent);
        if (null != binder)
        {
            return binder;
        }
        return mBinder;
    }

    @Override
    protected String   getServiceName()
    {
        return NetworkServiceTv.class.getCanonicalName();
    }

    @Override
    protected Class<?> getPeerService()
    {
        return AssistantServiceTv.class;
    }

}

在NetworkServiceTv中负责联网。这样即使其中一个进程因错误崩溃，也可以被启动再次联网。