Android 長按電源鍵關機整個流程小學習

Android 長按電源鍵關機整個流程小學習

最近研究了一下android關機跟重新啟動功能，看了一些長按電源鍵到彈出關機對話框，到真正關機的一系列處理過程。

首先還是來看看這個長按電源鍵都干了些什麼吧？一般來說，電源鍵都是接到PMU上的，PMU來判斷是長按還短按，當有按鍵消息產生的時候，系統會有中斷，然後去讀PMU的狀態就可以知道是什麼了。筆者以全志平台的AXP209小議一下，先貼上關鍵代碼：

static int axp_battery_event(struct notifier_block *nb, unsigned long event,
        void *data)
{
	struct axp_charger *charger =
	container_of(nb, struct axp_charger, nb);
    uint8_t w[9];
	w[0] = (uint8_t) ((event) & 0xFF);
	w[1] = POWER20_INTSTS2;
	w[2] = (uint8_t) ((event >> 8) & 0xFF);
	w[3] = POWER20_INTSTS3;
	w[4] = (uint8_t) ((event >> 16) & 0xFF);
	w[5] = POWER20_INTSTS4;
	w[6] = (uint8_t) ((event >> 24) & 0xFF);
	w[7] = POWER20_INTSTS5;
	w[8] = (uint8_t) (((uint64_t) event >> 32) & 0xFF);

	if(event & (AXP20_IRQ_BATIN|AXP20_IRQ_BATRE)) {
		axp_capchange(charger);
	}

	if(event & (AXP20_IRQ_ACIN|AXP20_IRQ_USBIN|AXP20_IRQ_ACOV|AXP20_IRQ_USBOV|AXP20_IRQ_CHAOV
				|AXP20_IRQ_CHAST|AXP20_IRQ_TEMOV|AXP20_IRQ_TEMLO)) {
		axp_change(charger);
	}

	if(event & (AXP20_IRQ_ACRE|AXP20_IRQ_USBRE)) {
		axp_change(charger);
	}

	if(event & AXP20_IRQ_PEKLO) {
		axp_presslong(charger);
	}

	if(event & AXP20_IRQ_PEKSH) {
		axp_pressshort(charger);
	}

	DBG_PSY_MSG("event = 0x%x\n",(int) event);
	axp_writes(charger->master,POWER20_INTSTS1,9,w);

	return 0;
}

短按跟長按具體也就是上報的延時區別，如下：

static void axp_presslong(struct axp_charger *charger)
{
	DBG_PSY_MSG("press long\n");
	input_report_key(powerkeydev, KEY_POWER, 1);
	input_sync(powerkeydev);
	ssleep(2);
	DBG_PSY_MSG("press long up\n");
	input_report_key(powerkeydev, KEY_POWER, 0);
	input_sync(powerkeydev);
}

static void axp_pressshort(struct axp_charger *charger)
{
	DBG_PSY_MSG("press short\n");
	input_report_key(powerkeydev, KEY_POWER, 1);
	input_sync(powerkeydev);
	msleep(100);
	input_report_key(powerkeydev, KEY_POWER, 0);
	input_sync(powerkeydev);
}

在inputmanager裡面再解析出是長按還是短按，來做相應處理。如果是長按，就彈出對話框，在彈出對話框之前，有幾次傳遞，還是activitymanger跟Windowsmanagerservice做宏觀調控，最終把消息傳到苦逼的ShutdownThread，不過ShutdownThread也不難弄。/*****************************************************************************************************/
聲明：本博內容均由http://blog.csdn.net/sundesheng125原創，轉載請注明出處，謝謝！
/*****************************************************************************************************/

首先來看一下，在ShutdownThread裡面有一個CloseDialogReceiver來關注Intent.ACTION_CLOSE_SYSTEM_DIALOGS，它收到這個消息就會關閉這個對話框。對話框怎麼起來的呢？請看下面的源碼：

        if (confirm) {
            final CloseDialogReceiver closer = new CloseDialogReceiver(context);
            final AlertDialog dialog = new AlertDialog.Builder(context)
                    .setTitle(com.android.internal.R.string.power_off)
                    .setMessage(resourceId)
                    .setPositiveButton(com.android.internal.R.string.yes, new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int which) {
                            beginShutdownSequence(context);
                        }
                    })
                    .setNegativeButton(com.android.internal.R.string.no, null)
                    .create();
            closer.dialog = dialog;
            dialog.setOnDismissListener(closer);
            dialog.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG);
            dialog.show();
        } else {
            beginShutdownSequence(context);
        }

其實就是一個AlertDialog，也沒什麼新鮮的，只是在setPositiveButton的時候注冊了clicklistener來監聽你是否按下了，按下了就直接執行beginShutdownSequence。在beginShutdownSequence還會彈出一個進度的對話框，代碼如下：

        ProgressDialog pd = new ProgressDialog(context);
        pd.setTitle(context.getText(com.android.internal.R.string.power_off));
        pd.setMessage(context.getText(com.android.internal.R.string.shutdown_progress));
        pd.setIndeterminate(true);
        pd.setCancelable(false);
        pd.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG);

        pd.show();

在裡面還會調用兩個非常重要的Power.shutdown()跟Power.reboot(reason)，看你是重啟還是關機了。

    /**
     * Low-level function turn the device off immediately, without trying
     * to be clean.  Most people should use
     * {@link android.internal.app.ShutdownThread} for a clean shutdown.
     *
     * @deprecated
     * @hide
     */
    @Deprecated
    public static native void shutdown();

    /**
     * Reboot the device.
     * @param reason code to pass to the kernel (e.g. "recovery"), or null.
     *
     * @throws IOException if reboot fails for some reason (eg, lack of
     *         permission)
     */
    public static void reboot(String reason) throws IOException
    {
        rebootNative(reason);
    }

    private static native void rebootNative(String reason) throws IOException ;

再往下跟，

static void android_os_Power_shutdown(JNIEnv *env, jobject clazz)
{
    android_reboot(ANDROID_RB_POWEROFF, 0, 0);
}

extern int go_recovery(void);

static void android_os_Power_reboot(JNIEnv *env, jobject clazz, jstring reason)
{
    if (reason == NULL) {
        android_reboot(ANDROID_RB_RESTART, 0, 0);
    } else {
        const char *chars = env->GetStringUTFChars(reason, NULL);
        //android_reboot(ANDROID_RB_RESTART2, 0, (char *) chars);
        go_recovery();
        android_reboot(ANDROID_RB_RESTART, 0, 0);
        env->ReleaseStringUTFChars(reason, chars);  // In case it fails.
    }
    jniThrowIOException(env, errno);
}

所以，整個流程都是好的，學習理了一下流程，大部分都是源碼，把它搞清楚也是有好處的。