Android 断开电源5秒后自动关机

最近在做行车记录仪的事情，由于车载设备上的锂电池容量比较小，所以在停车熄火，保存数据后需要自动关机，由于Shutdown的权限不对普通应用开放，所以需要在源码下编译代码。可以自己写个BroadcastReceiver放到Setting源码里，也可以是独立应用。

manifest节点需要声明系统级uid：

android:sharedUserId="android.uid.system"

以及关机权限：

<uses-permission android:name="android.permission.SHUTDOWN"/>

以上这两点在Setting的AndroidManifest里都有，所以就不用我们手动添加了。
然后我在Application里声明了两个全局变量，用来存储当前的电源状态和已经断开电源的秒数：

    /**
     * 电源是否连接
     */
    public static boolean isPowerConnect = true;

    /**
     * 电源断开的秒数
     */
    public static int OffSecond = 0;

接着就是PowerStateChangeReceiver：

package com.android.settings;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.Handler;
import android.os.Message;
import android.widget.Toast;

public class PowerStateChangeReceiver extends BroadcastReceiver {

    private Context context;

    @Override
    public void onReceive(Context context, Intent intent) {

        this.context = context;

        if ("android.intent.action.ACTION_POWER_CONNECTED".equals(intent
                .getAction())) {
            Screenshot.isPowerConnect = true;
            //Toast.makeText(context, "CONNECTED", Toast.LENGTH_SHORT).show();
        } else if ("android.intent.action.ACTION_POWER_DISCONNECTED"
                .equals(intent.getAction())) {
            Screenshot.isPowerConnect = false;
            //Toast.makeText(context, "DISCONNECTED", Toast.LENGTH_SHORT).show();
            new Thread(new shutdownThread()).start();
        }
    }

    /**
     * Shutdown
     * 
     * @param context
     */
    public void shutdown(Context context) {
        try {
            Intent intent = new Intent(
                    "android.intent.action.ACTION_REQUEST_SHUTDOWN");

            intent.putExtra("android.intent.extra.KEY_CONFIRM", false);

            intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            context.startActivity(intent);
        } catch (Exception e) {
        }
        Toast.makeText(context, context.getResources().getString(R.string.shutdown_now), Toast.LENGTH_SHORT).show();
    }

    public class shutdownThread implements Runnable {

        @Override
        public void run() {
            while (true) {

                try {
                    Thread.sleep(1000);
                    Message message = new Message();
                    message.what = 1;
                    shutdownHandler.sendMessage(message);
                    if (!Screenshot.isPowerConnect) {
                        Screenshot.OffSecond++;
                    } else {
                        Screenshot.OffSecond = 0;
                    }
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    final Handler shutdownHandler = new Handler() {
        public void handleMessage(Message msg) {
            switch (msg.what) {
            case 1:
                if (Screenshot.OffSecond == 5
                        && !Screenshot.isPowerConnect) {
                    shutdown(context);
                }
                break;

            default:
                break;
            }
        }
    };

}

另外是在setting的AndroidManifest.xml对reveiver的声明：

<receiver android:name=".PowerStateChangeReceiver" >
            <intent-filter>
                <action android:name="android.intent.action.ACTION_POWER_CONNECTED" />
                <action android:name="android.intent.action.ACTION_POWER_DISCONNECTED" />
            </intent-filter>
        </receiver>

okay，大功告成。