分析平臺Android4.4,

Android 系統架構中：一個manager類對應一個aidl介面，一個manager對應一個底層的服務，notification也是這個架構。

 1.一個普通apk呼叫notification實現呼吸燈燈效，主要是通過在Notification裡面設定效果引數傳入NotificationManagernotify方法 ，通過aidl介面轉換傳入NotificationManagerService

 需要設定如下程式碼：

1.1：獲取NotificationManager:

NotificationManager mNotificationManager=(NotificationManager)this.getSystemService(NOTIFICATION_SERVICE);

1.2:定義一個Notification:

  Notification  mNotification=new Notification();

1.3:設定Notification的各種屬性：

//設定通知在狀態列顯示的圖示

mNotification.icon=R.drawable.icon;          

//當我們點選通知時顯示的內容

mNotification.tickerText="Button1通知內容.....";                           

//通知時發出的預設聲音

mNotification.defaults=Notification.DEFAULT_SOUND;

Android支援三色燈提醒，可以根據不同的場景選擇點亮不同顏色的燈。需要注意的是，只有設定Notification的標誌位為FLAG_SHOW_LIGHTS，才能支援三色燈提醒。建立三色燈提醒的Notification示例如下：

mNotification.flags |= Notification.FLAG_SHOW_LIGHTS;

提醒標誌位（

Notification支援FLAG_SHOW_LIGHTS、FLAG_ONGOING_EVENT、FLAG_INSISTENT、FLAG_ ONLY_ALERT_ONCE、FLAG_AUTO_CANCEL、FLAG_NO_CLEAR、

FLAG_SHOW_LIGHTS //三色燈提醒

FLAG_ONGOING_EVENT //發起事件

FLAG_INSISTENT //振鈴音將持續到Notification取消或Notification視窗開啟

FLAG_ONLY_ALERT_ONCE //發起Notification後，振鈴音或振動均只執行一次

FLAG_AUTO_CANCEL //使用者單擊後自動消失

FLAG_NO_CLEAR //只有全部清除時，Notification才會清除

FLAG_FOREGROUND_SERVICE //表示正執行的服務）

mNotification.ledARGB = 0xff0000f;//Led顏色

mNotification.ledOnMS = 300;//led亮的時間

mNotification.ledOffMS = 300;;//led滅的時間

//設定通知顯示的引數

PendingIntent m_PendingIntent=PendingIntent.getActivity(NotificationDemo.this, 0, m_Intent, 0);

mNotification.setLatestEventInfo(NotificationDemo.this, "Button1", "Button1通知",m_PendingIntent );

//開始執行這個通知

mNotificationManager.notify(0,mNotification);

將設定好的引數資訊打包到m_Notification中傳入NotificationManager繼續處理

2.在frameworks/base/core/java/android/app/NotificationManager.java中

   static public INotificationManager getService()

    {

        if (sService != null) {

            return sService;

        }

        IBinder b = ServiceManager.getService("notification");

        sService = INotificationManager.Stub.asInterface(b);

        return sService;

}



  public void notify(String tag, int id, Notification notification)

    {

        int[] idOut = new int[1];

        INotificationManager service = getService();

        String pkg = mContext.getPackageName();

        if (notification.sound != null) {

            notification.sound = notification.sound.getCanonicalUri();

            if (StrictMode.vmFileUriExposureEnabled()) {

                notification.sound.checkFileUriExposed("Notification.sound");

            }

        }

        if (localLOGV) Log.v(TAG, pkg + ": notify(" + id + ", " + notification + ")");

        Notification stripped = notification.clone();

        Builder.stripForDelivery(stripped);

        try {

            service.enqueueNotificationWithTag(pkg, mContext.getOpPackageName(), tag, id,

                   stripped, idOut, UserHandle.myUserId());

            if (id != idOut[0]) {

                Log.w(TAG, "notify: id corrupted: sent " + id + ", got back " + idOut[0]);

            }

        } catch (RemoteException e) {

        }

    }

通過aidl介面呼叫到  NotificationManagerService中的enqueueNotificationWithTag方法中，enqueue說明notification的內部維護著一個佇列，接收不同apk傳送的通知請求。

3.在frameworks/base/services/core/java/com/android/server/notification/NotificationManagerService.java中實現了燈效，亮滅時長燈的邏輯控制。

其中定義了MAX_PACKAGE_NOTIFICATIONS = 50，最大可以接收五十個通知

        @Override

        public void enqueueNotificationWithTag(String pkg, String opPkg, String tag, int id,

                Notification notification, int[] idOut, int userId) throws RemoteException {

            enqueueNotificationInternal(pkg, opPkg, Binder.getCallingUid(),

                    Binder.getCallingPid(), tag, id,notification, idOut, userId);

        }

  void enqueueNotificationInternal(final String pkg, final String opPkg, final int callingUid,

            final int callingPid, final String tag, final int id, final Notificationnotification,

            int[] idOut, int incomingUserId) {……….

…………………………..

………………….

}在這裡對mNotificationList通知訊息佇列各條通知的優先順序，聲音進行了相關操作

最後進入updateLightsLocked在其中將設定好的燈效顏色，型別，時間長短寫入LightsService

      mNotificationLight.setFlashing(ledARGB, LightsService.LIGHT_FLASH_TIMED,

                        ledOnMS, ledOffMS);

4.在frameworks/base/services/core/java/com/android/server/lights/LightsService.java中setFlashing方法裡面setLightLocked來實現等效。

所有對燈效的操作都是通過setLightLocked實現。如下

        private void setLightLocked(int color, int mode, int onMS, int offMS, int brightnessMode) {

            if (color != mColor || mode != mMode || onMS != mOnMS || offMS != mOffMS) {

                if (DEBUG) Slog.v(TAG, "setLight #" + mId + ": color=#"

                        + Integer.toHexString(color));

                mColor = color;

                mMode = mode;

                mOnMS = onMS;

                mOffMS = offMS;

                Trace.traceBegin(Trace.TRACE_TAG_POWER, "setLight(" + mId + ", " + color + ")");

                try {

                    setLight_native(mNativePointer, mId, color, mode, onMS, offMS, brightnessMode);

                } finally {

                    Trace.traceEnd(Trace.TRACE_TAG_POWER);

                }

            }

        }



        private int mId;

        private int mColor;

        private int mMode;

        private int mOnMS;

        private int mOffMS;

        private boolean mFlashing;

    }

setLight_native最終呼叫了一個native方法，到JNI層去了。

在frameworks/base/services/core/jni/com_android_server_lights_LightsService.cpp中還是將LED燈顏色，模式，時間寫入state中向下繼續傳遞

static void setLight_native(JNIEnv *env, jobject clazz, jlong ptr,

        jint light, jint colorARGB, jint flashMode, jint onMS, jint offMS, jint brightnessMode)

{

    Devices* devices = (Devices*)ptr;

    light_state_t state;

    if (light < 0 || light >= LIGHT_COUNT || devices->lights[light] == NULL) {

        return ;

    }

    memset(&state, 0, sizeof(light_state_t));

    state.color = colorARGB;

    state.flashMode = flashMode;

    state.flashOnMS = onMS;

    state.flashOffMS = offMS;

    state.brightnessMode = brightnessMode;

    {

        ALOGD_IF_SLOW(50, "Excessive delay setting light");

        devices->lights[light]->set_light(devices->lights[light], &state);

    }

}

最後通過hardwareinterface控制led燈顏色節點實現燈效的具體效果！