android SystemUI 流程分析
android4 SystemUI 流程分析
什么是SystemUI？
对于Phone来说SystemUI指的是：StatusBar(状态栏)、NavigationBar(导航栏)。而对于Tablet或者是TV来说SystemUI指的是：CombinedBar(包括了StatusBar和NavigationBar)。
启动后Phone界面上的信号，蓝牙标志，Wifi标志等等这些状态显示标志都会在StatusBar上显示。当我们的设备开机后，首先
需要给用户呈现的就是各种界面同时也包括了我们的SystemUI，因此对于整个Android系统来说，SystemUI都有举足轻重的作用。
现在就从代码开始一步步的分析
1、启动流程
代码路径：fameworks/base/packages/SystemUI
建立工程导入到eclipse中代码具体图示：
先从 AndroidManifest.xml 看看有哪些东东，以前说过android中有四大组件，这里就有如下的三大部分：
系统服务 Service ：
SystemUIService
TakeScreenshotService
LoadAverageService
广播接收器 BroadcastReceive:
BootReceiver
Activity 应用：
USB的挺多哟...
UsbStorageActivity
UsbConfirmActivity
UsbPermissionActivity
UsbStorageActivity
UsbAccessoryUriActivity
NetworkOverLimitActivity
Nyandroid
具体定义请看 AndroidManifest.xml 文件,上面只是简单的列一下
先看第一个Activity -- Nyandroid 这里做了什么呢？
就是网上传说中的 好多安卓机器人飞过去。。。。其中代码很简单，简单说一下动画效果的代码：
public class FlyingCat extends ImageView {
public FlyingCat(Context context, AttributeSet as) {
super(context, as);
setImageResource(R.drawable.nyandroid_anim); // @@@
if (DEBUG) setBackgroundColor(0x80FF0000);
}
...
}定义在 frameworks\base\packages\SystemUI\res\drawable\nyandroid_anim.xml
相关图片在： frameworks\base\packages\SystemUI\res\drawable-nodpi 如图示：
然后再看最重要的服务：SystemUIService
一般来说，Service启动一般由开机广播或者StartService/BindService这几种方式来启动。既然这个Service是一个系统
服务，应该是由系统这边启动，那么看下 SystemServer.java ,果然发现如下启动代码：
startSystemUi(contextF);
static final void startSystemUi(Context context) {
Intent intent = new Intent();
intent.setComponent(new ComponentName("com.android.systemui",
"com.android.systemui.SystemUIService"));
Slog.d(TAG, "Starting service: " + intent);
context.startService(intent);
}对于Android启动流程请看如下系统文章：
http://blog.csdn.net/andyhuabing/article/details/7346203 android启动--深入理解init进程
http://blog.csdn.net/andyhuabing/article/details/7349986 android启动--深入理解zygote
http://blog.csdn.net/andyhuabing/article/details/7351691 android启动--深入理解zygote (II)
http://blog.csdn.net/andyhuabing/article/details/7353910 android启动--深入理解启动HOME
那么就继续跟踪 SystemUIService 中代码：
/**
* The class names of the stuff to start.
*/
final Object[] SERVICES = new Object[] {
0, // system bar or status bar, filled in below.
com.android.systemui.power.PowerUI.class,
};
@Override
public void onCreate() {
// Pick status bar or system bar.
IWindowManager wm = IWindowManager.Stub.asInterface(
ServiceManager.getService(Context.WINDOW_SERVICE));
try {
SERVICES[0] = wm.canStatusBarHide()
? R.string.config_statusBarComponent
: R.string.config_systemBarComponent;
} catch (RemoteException e) {
Slog.w(TAG, "Failing checking whether status bar can hide", e);
}
final int N = SERVICES.length;
mServices = new SystemUI[N];
for (int i=0; i在这代码中：
SERVICES[0] = wm.canStatusBarHide()
? R.string.config_statusBarComponent
: R.string.config_systemBarComponent;
通过AIDL获取WindowManager对象并调用 wm.canStatusBarHide() 这个代码在哪里呢？
查看: frameworks/base/policy/src/com/android/internal/policy/impl/PhoneWindowManager.java
public boolean canStatusBarHide() {
return mStatusBarCanHide;
}
public void setInitialDisplaySize(int width, int height) {
...
// Determine whether the status bar can hide based on the size
// of the screen. We assume sizes > 600dp are tablets where we
// will use the system bar.
int shortSizeDp = shortSize
* DisplayMetrics.DENSITY_DEFAULT
/ DisplayMetrics.DENSITY_DEVICE;
mStatusBarCanHide = shortSizeDp < 600;
}从以上代码来看，shortSizeDp小于600dp时，则系统会认为该设备是Phone反之则认为是Tablet。
根据mStatusBarCanHide的值，设定StatusBar或者SystemBar(CombinedBar)的高度，以及是否显示NavigationBar。
2、StatusBar(状态栏)及NavigationBar(导航栏)
如果是 StatusBar 则 SERVICES[0] 存放 com.android.systemui.statusbar.phone.PhoneStatusBar 否则存放
com.android.systemui.statusbar.tablet.TabletStatusBar
SERVICES[1] 存放 com.android.systemui.power.PowerUI.class
从我的机器上打印来看，
E/SystemServer( 1299): Starting service: Intent { cmp=com.android.systemui/.SystemUIService }
D/SystemUIService( 1382): running: com.android.systemui.statusbar.tablet.TabletStatusBar@415b8b20
D/SystemUIService( 1382): running: com.android.systemui.power.PowerUI@416b5ae8
I/PowerUI ( 1382): start
然后调用 mServices[i].start();那么就分析 TabletStatusBar 中的start方法吧
@Override
public void start() {
super.start(); // will add the main bar view
}调用到 frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/StatusBar.java
public void start() {
// First set up our views and stuff.
View sb = makeStatusBarView();
// Connect in to the status bar manager service
StatusBarIconList iconList = new StatusBarIconList();
ArrayList notificationKeys = new ArrayList();
ArrayList notifications = new ArrayList();
mCommandQueue = new CommandQueue(this, iconList);
mBarService = IStatusBarService.Stub.asInterface(
ServiceManager.getService(Context.STATUS_BAR_SERVICE));
int[] switches = new int[7];
ArrayList binders = new ArrayList();
try {
mBarService.registerStatusBar(mCommandQueue, iconList, notificationKeys, notifications,
switches, binders);
} catch (RemoteException ex) {
// If the system process isn't there we're doomed anyway.
}
disable(switches[0]);
setSystemUiVisibility(switches[1]);
topAppWindowChanged(switches[2] != 0);
// StatusBarManagerService has a back up of IME token and it's restored here.
setImeWindowStatus(binders.get(0), switches[3], switches[4]);
setHardKeyboardStatus(switches[5] != 0, switches[6] != 0);
// Set up the initial icon state
int N = iconList.size();
int viewIndex = 0;
for (int i=0; i
在这里，完成了SystemUI的整个初始化以及设置过程，并最终呈现到界面上。
启动过程中完成如下操作：
1、获取icon list，addIcon(iconList.getSlot(i), i, viewIndex, icon);
2、获取notification,addNotification(notificationKeys.get(i), notifications.get(i));
3、显示StatusBar,WindowManagerImpl.getDefault().addView(sb, lp);
显示NavigationBar，WindowManagerImpl.getDefault().addView(
mNavigationBarView, getNavigationBarLayoutParams());
时序图如下：
3、最近任务缩略图显示
长按home键，列出最近启动过的任务缩略图,重要的两个类
// Recent apps
private RecentsPanelView mRecentsPanel;
private RecentTasksLoader mRecentTasksLoader;
SystemUI 获取按键事件，获取缩略图并将其显示出来，最后响应view上按键响应相应事件：
对于我们来说，关注点主要有如下几个：
1、缩略图如何获取
RecentsPanelView.java 中
refreshRecentTasksList(recentTaskDescriptions);
-->
mRecentTaskDescriptions = mRecentTasksLoader.getRecentTasks();
-->
RecentTasksLoader.java 中
// return a snapshot of the current list of recent apps
ArrayList getRecentTasks() {
cancelLoadingThumbnails();
ArrayList tasks = new ArrayList();
final PackageManager pm = mContext.getPackageManager();
final ActivityManager am = (ActivityManager)
mContext.getSystemService(Context.ACTIVITY_SERVICE);
final List recentTasks =
am.getRecentTasks(MAX_TASKS, ActivityManager.RECENT_IGNORE_UNAVAILABLE);
ActivityInfo homeInfo = new Intent(Intent.ACTION_MAIN).addCategory(Intent.CATEGORY_HOME)
.resolveActivityInfo(pm, 0);
HashSet recentTasksToKeepInCache = new HashSet();
int numTasks = recentTasks.size();
// skip the first task - assume it's either the home screen or the current activity.
final int first = 1;
recentTasksToKeepInCache.add(recentTasks.get(0).persistentId);
for (int i = first, index = 0; i < numTasks && (index < MAX_TASKS); ++i) {
final ActivityManager.RecentTaskInfo recentInfo = recentTasks.get(i);
TaskDescription item = createTaskDescription(recentInfo.id,
recentInfo.persistentId, recentInfo.baseIntent,
recentInfo.origActivity, recentInfo.description, homeInfo);
if (item != null) {
tasks.add(item);
++index;
}
}
// when we're not using the TaskDescription cache, we load the thumbnails in the
// background
loadThumbnailsInBackground(new ArrayList(tasks));
return tasks;
}
这里利用 ActivityManager 中的方法：getRecentTasks 获取当前任务的列表，然后再利用 getTaskThumbnails 获取
按键View 就是几个按键相应的View
public View getRecentsButton() {
return mCurrentView.findViewById(R.id.recent_apps);
}
public View getMenuButton() {
return mCurrentView.findViewById(R.id.menu);
}
public View getBackButton() {
return mCurrentView.findViewById(R.id.back);
}
public View getHomeButton() {
return mCurrentView.findViewById(R.id.home);
}
相应的应用缩略图，调用序列图如下:
2、显示缩略图
public void show(boolean show, boolean animate,
ArrayList recentTaskDescriptions) {
if (show) {
// Need to update list of recent apps before we set visibility so this view's
// content description is updated before it gets focus for TalkBack mode
refreshRecentTasksList(recentTaskDescriptions);
// if there are no apps, either bring up a "No recent apps" message, or just
// quit early
boolean noApps = (mRecentTaskDescriptions.size() == 0);
if (mRecentsNoApps != null) { // doesn't exist on large devices
mRecentsNoApps.setVisibility(noApps ? View.VISIBLE : View.INVISIBLE);
} else {
if (noApps) {
if (DEBUG) Log.v(TAG, "Nothing to show");
return;
}
}
}else {
mRecentTasksLoader.cancelLoadingThumbnails();
mRecentTasksDirty = true;
}
...
}
如果 mRecentsNoApps 为空则表示没有任务，显示 "No recent apps" 否则显示应用列表
否则则显示任务的缩略图。时序图如下：
3、点击某个缩略图执行
这里分为点击某个缩略图执行程序及长按缩略图执行程序
这里直接继承了 View.OnItemClickListener 所以可以直接执行子项按键事件
public class RecentsPanelView extends RelativeLayout implements OnItemClickListener, RecentsCallback,
StatusBarPanel, Animator.AnimatorListener, View.OnTouchListener
处理点击事件方法：
public void onItemClick(AdapterView parent, View view, int position, long id) {
handleOnClick(view);
}
public void handleOnClick(View view) {
TaskDescription ad = ((ViewHolder) view.getTag()).taskDescription;
final Context context = view.getContext();
final ActivityManager am = (ActivityManager)
context.getSystemService(Context.ACTIVITY_SERVICE);
if (ad.taskId >= 0) {
// This is an active task; it should just go to the foreground.
am.moveTaskToFront(ad.taskId, ActivityManager.MOVE_TASK_WITH_HOME);
} else {
Intent intent = ad.intent;
intent.addFlags(Intent.FLAG_ACTIVITY_LAUNCHED_FROM_HISTORY
| Intent.FLAG_ACTIVITY_TASK_ON_HOME
| Intent.FLAG_ACTIVITY_NEW_TASK);
if (DEBUG) Log.v(TAG, "Starting activity " + intent);
context.startActivity(intent);
}
hide(true);
}
注意代码：context.startActivity(intent); 这里就是执行对应的 Activity
处理长按键点击事件方法：
public void handleLongPress(
final View selectedView, final View anchorView, final View thumbnailView) {
thumbnailView.setSelected(true);
PopupMenu popup = new PopupMenu(mContext, anchorView == null ? selectedView : anchorView);
popup.getMenuInflater().inflate(R.menu.recent_popup_menu, popup.getMenu());
popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
public boolean onMenuItemClick(MenuItem item) {
if (item.getItemId() == R.id.recent_remove_item) {
mRecentsContainer.removeViewInLayout(selectedView);
} else if (item.getItemId() == R.id.recent_inspect_item) {
ViewHolder viewHolder = (ViewHolder) selectedView.getTag();
if (viewHolder != null) {
final TaskDescription ad = viewHolder.taskDescription;
startApplicationDetailsActivity(ad.packageName);
mBar.animateCollapse();
} else {
throw new IllegalStateException("Oops, no tag on view " + selectedView);
}
} else {
return false;
}
return true;
}
});
popup.setOnDismissListener(new PopupMenu.OnDismissListener() {
public void onDismiss(PopupMenu menu) {
thumbnailView.setSelected(false);
}
});
popup.show();
}
这里弹出一个PopupMenu,分别是 A:"Remove from list" 及 B:"App Info"
其中A项表示将此任务移除出列表，执行 mRecentsContainer.removeViewInLayout(selectedView);
另外B是启动另外一个Acitivty列出应用信息：
private void startApplicationDetailsActivity(String packageName) {
Intent intent = new Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS,
Uri.fromParts("package", packageName, null));
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
getContext().startActivity(intent);
}
总结：
这里详细的对SystemUI 的两个最重要的 StatusBar NavigationBar(SystemUIService) 及缩略图代码流程分析。
因此各家厂商根据自家的需求，需要定制SystemUI或者美化SystemUI，不同的平台也会有不同的修改，但大体框架是没有变的，
无非是在原有基础上的修修改改或者增加一些自己的类等等。