Android 5.1关机流程分析（1）

最新推荐文章于 2023-09-06 23:45:00 发布

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本文深入探讨了Android系统中从用户长按电源键到显示关机对话框的完整流程。详细分析了PhoneWindowManager如何处理电源键事件，以及系统如何通过发送MSG_POWER_LONG_PRESS消息并依据config.xml设置决定执行的操作。

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本文我们来分析下android关机流程之长按power键到dialog界面。

用户长按power键，系统是在PhoneWindowManager.java下面的interceptKeyBeforeQueueing函数处理事件。

public int interceptKeyBeforeQueueing(KeyEvent event, int policyFlags) {

......

            case KeyEvent.KEYCODE_POWER: {
                result &= ~ACTION_PASS_TO_USER;
                isWakeKey = false; // wake-up will be handled separately
                if (down) {
                    interceptPowerKeyDown(event, interactive);
                } else {
                    interceptPowerKeyUp(event, interactive, canceled);
                }
                break;
            }

......

}

接着interceptPowerKeyDown会发送MSG_POWER_LONG_PRESS消息

private void interceptPowerKeyDown(KeyEvent event, boolean interactive) {

......

        if (!mPowerKeyHandled) {
            if (interactive) {
                // When interactive, we're already awake.
                // Wait for a long press or for the button to be released to decide what to do.
                if (hasLongPressOnPowerBehavior()) {
                    Message msg = mHandler.obtainMessage(MSG_POWER_LONG_PRESS);
                    msg.setAsynchronous(true);
                    mHandler.sendMessageDelayed(msg,
                            ViewConfiguration.get(mContext).getDeviceGlobalActionKeyTimeout());
                }
            } else {
                wakeUpFromPowerKey(event.getDownTime());
                final int maxCount = getMaxMultiPressPowerCount();

                if (maxCount <= 1) {
                    mPowerKeyHandled = true;
                } else {
                    mBeganFromNonInteractive = true;
                }
            }
        }

......
}

private void interceptPowerKeyDown(KeyEvent event, boolean interactive) {

......

        if (!mPowerKeyHandled) {
            if (interactive) {
                // When interactive, we're already awake.
                // Wait for a long press or for the button to be released to decide what to do.
                if (hasLongPressOnPowerBehavior()) {
                    Message msg = mHandler.obtainMessage(MSG_POWER_LONG_PRESS);
                    msg.setAsynchronous(true);
                    mHandler.sendMessageDelayed(msg,
                            ViewConfiguration.get(mContext).getDeviceGlobalActionKeyTimeout());
                }
            } else {
                wakeUpFromPowerKey(event.getDownTime());
                final int maxCount = getMaxMultiPressPowerCount();

                if (maxCount <= 1) {
                    mPowerKeyHandled = true;
                } else {
                    mBeganFromNonInteractive = true;
                }
            }
        }

......
}

MSG_POWER_LONG_PRESS 消息的处理代码：

 private class PolicyHandler extends Handler {
        @Override
        public void handleMessage(Message msg) {
......

            case MSG_POWER_LONG_PRESS:
                    powerLongPress();
                    break;

......

}

powerLongPress会根据power键设定的值执行对应的代码

private void powerLongPress() {
        final int behavior = getResolvedLongPressOnPowerBehavior();
        switch (behavior) {
        case LONG_PRESS_POWER_NOTHING:
            break;
        case LONG_PRESS_POWER_GLOBAL_ACTIONS:
            mPowerKeyHandled = true;
            if (!performHapticFeedbackLw(null, HapticFeedbackConstants.LONG_PRESS, false)) {
                performAuditoryFeedbackForAccessibilityIfNeed();
            }
            showGlobalActionsInternal();
            break;
        case LONG_PRESS_POWER_SHUT_OFF:
        case LONG_PRESS_POWER_SHUT_OFF_NO_CONFIRM:
            mPowerKeyHandled = true;
            performHapticFeedbackLw(null, HapticFeedbackConstants.LONG_PRESS, false);
            sendCloseSystemWindows(SYSTEM_DIALOG_REASON_GLOBAL_ACTIONS);
            mWindowManagerFuncs.shutdown(behavior == LONG_PRESS_POWER_SHUT_OFF);
            break;
        }
    }

power键长按执行代码由config.xml设定

 <!-- Control the behavior when the user long presses the power button.
            0 - Nothing
            1 - Global actions menu
            2 - Power off (with confirmation)
            3 - Power off (without confirmation)
    -->
    <integer name="config_longPressOnPowerBehavior">1</integer>