[置顶] Android FrameWork Service 之 StatusBarService

android的状态栏：

在android中，状态栏不属于某个应用程序，而是系统的一部分，是通过StatusBarService来管理的。

Android通过StatusBarPolicy及StatusBarService来管理状态栏。
一．StatusBarPolicy 负责状态栏显示的策略管理
Android中状态栏上有很多图标，这些图标什么时候显示什么时候不显示？这些都是 StatusBarPolicy来管理的。
StatusBarPolicy的构造函数里初始化了好几个图标，如时间icon，闹钟icon，信号栏icon等。默认时有很多图标是不显示的，需要显示时再进行更新。StatusBarPolicy调用 registerReceiver注册了感兴趣的intent,当感兴趣的intent发生时，对图标进行更新。例如，设置一个闹钟后，闹钟模块会发出一个叫做Intent.ACTION_ALARM_CHANGED的intent，然后StatusBarPolicy接收到此intent，继而更新状态栏上的闹钟图标。
见如下的代码：

private StatusBarPolicy(Context context, StatusBarService service) {
mContext = context;
mService = service;

// clock
mCalendar = Calendar.getInstance(TimeZone.getDefault());
mClockData = IconData.makeText("clock", "");
mClockIcon = service.addIcon(mClockData, null);
updateClock();

// battery
mBatteryData = IconData.makeIcon("battery",
null, com.android.internal.R.drawable.stat_sys_battery_unknown, 0, 0);
mBatteryIcon = service.addIcon(mBatteryData, null);

// phone_signal
mPhone = (TelephonyManager)context.getSystemService(Context.TELEPHONY_SERVICE);
mPhoneData = IconData.makeIcon("phone_signal",
null, com.android.internal.R.drawable.stat_sys_signal_null, 0, 0);
mPhoneIcon = service.addIcon(mPhoneData, null);
// register for phone state notifications.
((TelephonyManager)mContext.getSystemService(Context.TELEPHONY_SERVICE))
.listen(mPhoneStateListener,
PhoneStateListener.LISTEN_SERVICE_STATE
| PhoneStateListener.LISTEN_SIGNAL_STRENGTH
| PhoneStateListener.LISTEN_CALL_STATE
| PhoneStateListener.LISTEN_DATA_CONNECTION_STATE
| PhoneStateListener.LISTEN_DATA_ACTIVITY);

// data_connection
mDataData = IconData.makeIcon("data_connection",
null, com.android.internal.R.drawable.stat_sys_data_connected_g, 0, 0);
mDataIcon = service.addIcon(mDataData, null);
service.setIconVisibility(mDataIcon, false);

// wifi
mWifiData = IconData.makeIcon("wifi", null, sWifiSignalImages[0], 0, 0);
mWifiIcon = service.addIcon(mWifiData, null);
service.setIconVisibility(mWifiIcon, false);
// wifi will get updated by the sticky intents

// bluetooth status
mBluetoothData = IconData.makeIcon("bluetooth",
null, com.android.internal.R.drawable.stat_sys_data_bluetooth, 0, 0);
mBluetoothIcon = service.addIcon(mBluetoothData, null);
updateBluetooth(null);

// Gps status
mGpsEnabledIconData = IconData.makeIcon("gps",
null, com.android.internal.R.drawable.stat_sys_gps_acquiring_anim, 0, 0);
mGpsFixIconData = IconData.makeIcon("gps",
null, com.android.internal.R.drawable.stat_sys_gps_on, 0, 0);
mGpsIcon = service.addIcon(mGpsEnabledIconData, null);
service.setIconVisibility(mGpsIcon, false);

// Alarm clock
mAlarmClockIconData = IconData.makeIcon(
"alarm_clock",
null, com.android.internal.R.drawable.stat_notify_alarm, 0, 0);
mAlarmClockIcon = service.addIcon(mAlarmClockIconData, null);
service.setIconVisibility(mAlarmClockIcon, false);

// Sync state
mSyncActiveIcon = service.addIcon(IconData.makeIcon("sync_active",
null, R.drawable.stat_notify_sync_anim0, 0, 0), null);
mSyncFailingIcon = service.addIcon(IconData.makeIcon("sync_failing",
null, R.drawable.stat_notify_sync_error, 0, 0), null);
service.setIconVisibility(mSyncActiveIcon, false);
service.setIconVisibility(mSyncFailingIcon, false);

// volume
mVolumeData = IconData.makeIcon("volume",
null, com.android.internal.R.drawable.stat_sys_ringer_silent, 0, 0);
mVolumeIcon = service.addIcon(mVolumeData, null);
service.setIconVisibility(mVolumeIcon, false);

IntentFilter filter = new IntentFilter();

// Register for Intent broadcasts for...
filter.addAction(Intent.ACTION_TIME_TICK);
filter.addAction(Intent.ACTION_TIME_CHANGED);
filter.addAction(Intent.ACTION_CONFIGURATION_CHANGED);
filter.addAction(Intent.ACTION_BATTERY_CHANGED);
filter.addAction(Intent.ACTION_TIMEZONE_CHANGED);
filter.addAction(Intent.ACTION_ALARM_CHANGED);
filter.addAction(Intent.ACTION_SYNC_STATE_CHANGED);
filter.addAction(AudioManager.RINGER_MODE_CHANGED_ACTION);
filter.addAction(AudioManager.VIBRATE_SETTING_CHANGED_ACTION);
filter.addAction(BluetoothIntent.ENABLED_ACTION);
filter.addAction(BluetoothIntent.DISABLED_ACTION);
filter.addAction(BluetoothIntent.HEADSET_STATE_CHANGED_ACTION);
filter.addAction(BluetoothA2dp.SINK_STATE_CHANGED_ACTION);
filter.addAction(WifiManager.WIFI_STATE_CHANGED_ACTION);
filter.addAction(WifiManager.SUPPLICANT_CONNECTION_CHANGE_ACTION);
filter.addAction(WifiManager.NETWORK_STATE_CHANGED_ACTION);
filter.addAction(WifiManager.RSSI_CHANGED_ACTION);
filter.addAction(GpsLocationProvider.GPS_ENABLED_CHANGE_ACTION);
filter.addAction(GpsLocationProvider.GPS_FIX_CHANGE_ACTION);
filter.addAction(TelephonyIntents.ACTION_SIM_STATE_CHANGED);
mContext.registerReceiver(mIntentReceiver, filter, null, mHandler);
}

二．StatusBarService
正如上面看到的，StatusBarPolicy只是一个策略管理，实际的功能是StatusBarService来实现的。StatusBarService初始化时初始化了一个用于显示statusbar 的StatusBarView。StatusBarView里面定义了icon名字，的显示顺序，对应的png图等。代码如下：

public StatusBarService(Context context) {
mContext = context;
mDisplay = ((WindowManager)context.getSystemService(
Context.WINDOW_SERVICE)).getDefaultDisplay();
makeStatusBarView(context);
mUninstallReceiver = new UninstallReceiver();
}

private void makeStatusBarView(Context context) {
Resources res = context.getResources();
mRightIconSlots = res.getStringArray(com.android.internal.R.array.status_bar_icon_order);
mRightIcons = new StatusBarIcon[mRightIconSlots.length];

ExpandedView expanded = (ExpandedView)View.inflate(context,
com.android.internal.R.layout.status_bar_expanded, null);
expanded.mService = this;
StatusBarView sb = (StatusBarView)View.inflate(context,
com.android.internal.R.layout.status_bar, null);
sb.mService = this;
……
}

mRightIconSlots 是一个String型数组，里面记录了状态栏上各个图标的名字。StatusBarPolicy就是根据这个名字找到相应的icon，调用setIcon设置其图标。mRightIconSlots的值从\frameworks\base\core\res\res\values\arrays.xml 中获得，现摘取片段如下：

<string-array name="status_bar_icon_order">
<item>clock</item>
<item>alarm_clock</item>
<item>battery</item>
<item>phone_signal</item>
<item>data_connection</item>
<item>volume</item>
<item>mute</item>
<item>speakerphone</item>
<item>wifi</item>
<item>bluetooth</item>
<item>gps</item>
<item>sync_active</item>
<item>sync_failing</item>
<item>ime</item>
</string-array>

由此已经可以看出要增加一个系统级图标，应该在此xml中增加相应的item，然后在StatusBarPolicy中做相应修改即可。

三代码例子

下面给个例子

原生态的android系统是没有耳机插入或未插入的状态指示的，本文就是讲解如何添加耳机插入的状态指示。效果图如下：

[置顶] Android FrameWork Service 之 StatusBarService_第1张图片

如图，当插入耳机后，在status bar上出现了一个耳机的图标。
这个耳机的图标和sim卡信号等图标在status bar的右边，因此这个实现肯定不是通过notification实现的，那么添加这个功能只能在framwork里面寻找了。具体的修改步骤如下：
1.在frameworks/base/core/res/res/drawable-mdpi目录先添加一个stat_sys_headset.png资源文件。这里面资源文件的目录要根据设备的分辨率来确定，我的设备是HVGA的，因此资源文件放在drawable-mdpi目录下。
2.修改frameworks/base/services/java/com/android/server/status/StatusBarPolicy.java

public class StatusBarPolicy {
private static final String TAG = "StatusBarPolicy";

private static StatusBarPolicy sInstance;
.....

// alarm clock
// Icon lit when clock is set
private IBinder mAlarmClockIcon;
private IconData mAlarmClockIconData;

//modify here start
//HeadSet
private IBinder mHeadSetPlugIcon;
private IconData mHeadSetPlugIconData;
//modify here end
.....

private BroadcastReceiver mIntentReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (action.equals(Intent.ACTION_TIME_TICK)) {
updateClock();
}
.....
else if (action.equals(Intent.ACTION_ALARM_CHANGED)) {
updateAlarm(intent);
}
//modify here start
else if (action.equals(Intent.ACTION_HEADSET_PLUG)) {
updateHeadset(intent);
}
//modify here end
else if (action.equals(Intent.ACTION_SYNC_STATE_CHANGED)) {
updateSyncState(intent);
}
......
};
private StatusBarPolicy(Context context, StatusBarService service) {
mContext = context;
mService = service;
mSignalStrength = new SignalStrength();
if(FeatureOption.MTK_GEMINI_SUPPORT == true) {
mSignalStrengthGemini = new SignalStrength();
}
mBatteryStats = BatteryStatsService.getService();
....
//modify here start
//HeadSet
mHeadSetPlugIconData = IconData.makeIcon(
"headset",
null,com.android.internal.R.drawable.stat_sys_headset, 0, 0);
mHeadSetPlugIcon = service.addIcon(mHeadSetPlugIconData, null);
service.setIconVisibility(mHeadSetPlugIcon, false);
//modify here end
....

IntentFilter filter = new IntentFilter();

// Register for Intent broadcasts for...
filter.addAction(Intent.ACTION_TIME_TICK);
....
//modify here start
filter.addAction(Intent.ACTION_HEADSET_PLUG);
//modify here end
....

}

//modify here start
private final void updateHeadset(Intent intent) {

Slog.d(TAG, "updateHeadset: state=" + intent.getIntExtra("state", 0));
mService.setIconVisibility(mHeadSetPlugIcon, (intent.getIntExtra("state", 0) == 1)?true:false);
}
//modify here end
.....
}

3.修改frameworks/base/core/res/res/values/arrays.xml

<string-array name="status_bar_icon_order">
<item><xliff:g id="id">clock</xliff:g></item>
<item><xliff:g id="id">secure</xliff:g></item>
<item><xliff:g id="id">alarm_clock</xliff:g></item>
<item><xliff:g id="id">battery</xliff:g></item>
<item><xliff:g id="id">phone_signal_2</xliff:g></item>
<item><xliff:g id="id">phone_signal</xliff:g></item>
<item><xliff:g id="id">phone_evdo_signal</xliff:g></item>
<item><xliff:g id="id">data_connection</xliff:g></item>
<item><xliff:g id="id">cdma_eri</xliff:g></item>
<item><xliff:g id="id">tty</xliff:g></item>
<item><xliff:g id="id">volume</xliff:g></item>
<item><xliff:g id="id">mute</xliff:g></item>
<item><xliff:g id="id">speakerphone</xliff:g></item>

<item><xliff:g id="id">headset</xliff:g></item>

<item><xliff:g id="id">wifi</xliff:g></item>
<item><xliff:g id="id">tty</xliff:g></item>
<item><xliff:g id="id">bluetooth</xliff:g></item>
<item><xliff:g id="id">gps</xliff:g></item>
<item><xliff:g id="id">sync_active</xliff:g></item>
<item><xliff:g id="id">sync_failing</xliff:g></item>
<item><xliff:g id="id">ime</xliff:g></item>
</string-array>
其中“headset”这个字符串就是“mHeadSetPlugIconData = IconData.makeIcon( "headset", null0, 0);”中的第一个参数。“<item><xliff:g id="id">headset</xliff:g></item> ”这个语句的位置于图标在status bar上显示的位置有关。

按照这3个步骤修改后重新编译源码之后，就可以看到如上图的效果了。

android的状态栏：

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