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Android启动流程④Launcher启动过程
Android系统的Home应用程序Launcher是由ActivityManagerService启动的，而ActivityManagerService和PackageManagerService一样，都是在开机时由SystemServer组件启动的，SystemServer组件首先是启动PackageManagerServic，由它来负责安装系统的应用程序，系统中的应用程序安装好了以后，SystemServer组件接下来就要通过ActivityManagerService来启动Home应用程序Launcher了，Launcher在启动的时候便会通过PackageManagerServic把系统中已经安装好的应用程序以快捷图标的形式展示在桌面上，这样用户就启动这些应用程序。
Launcher启动流程
启动Launcher时通过调用ActivityManagerService的systemReady函数实现的
frameworks/base/services/java/com/android/server/SystemServer.java
private void startOtherServices() {
...
mActivityManagerService.systemReady(new Runnable() {
@Override
public void run() {
Slog.i(TAG, "Making services ready");
mSystemServiceManager.startBootPhase(
SystemService.PHASE_ACTIVITY_MANAGER_READY);
...
}
...
}SystemServer.java中的startOtherServices方法中调用ActivityManagerService的systemReady函数。
public void systemReady(final Runnable goingCallback) {
···
···
mStackSupervisor.resumeFocusedStackTopActivityLocked();
mUserController.sendUserSwitchBroadcastsLocked(-1, currentUserId);
}
systemReady方法会调用ActivityStackSupervisor.java的resumeFocusedStackTopActivityLocked方法
frameworks/base/services/core/java/com/android/server/am/ActivityStackSupervisor.java
boolean resumeFocusedStackTopActivityLocked(
ActivityStack targetStack, ActivityRecord target, ActivityOptions targetOptions) {
if (targetStack != null && isFocusedStack(targetStack)) {
return targetStack.resumeTopActivityUncheckedLocked(target, targetOptions);
}
final ActivityRecord r = mFocusedStack.topRunningActivityLocked();
if (r == null || r.state != RESUMED) {
mFocusedStack.resumeTopActivityUncheckedLocked(null, null);
}
return false;
}
resumeFocusedStackTopActivityLocked会调用ActivityStack.java的resumeTopActivityUncheckedLocked方法，ActivityStack对象用于描述Activity堆栈。
frameworks/base/services/core/java/com/android/server/am/ActivityStack.java
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//* Ensure that the top activity in the stack is resumed.
boolean resumeTopActivityUncheckedLocked(ActivityRecord prev, ActivityOptions options) {
if (mStackSupervisor.inResumeTopActivity) {
// Don't even start recursing.
return false;
}
boolean result = false;
try {
// Protect against recursion.
mStackSupervisor.inResumeTopActivity = true;
if (mService.mLockScreenShown == ActivityManagerService.LOCK_SCREEN_LEAVING) {
mService.mLockScreenShown = ActivityManagerService.LOCK_SCREEN_HIDDEN;
mService.updateSleepIfNeededLocked();
}
//
result = resumeTopActivityInnerLocked(prev, options);
} finally {
mStackSupervisor.inResumeTopActivity = false;
}
return result;
}
resumeTopActivityUncheckedLocked会调用resumeTopActivityInnerLocked方法
frameworks/base/services/core/java/com/android/server/am/ActivityStack.java
private boolean resumeTopActivityInnerLocked(ActivityRecord prev, ActivityOptions options) {
···
if (next == null) {
// There are no more activities!
···
// Only resume home if on home display
return isOnHomeDisplay() &&
mStackSupervisor.resumeHomeStackTask(returnTaskType, prev, reason);
}
···
}
resumeTopActivityInnerLocked方法调用ActivityStackSupervisor.java的resumeHomeStackTask方法
frameworks/base/services/core/java/com/android/server/am/ActivityStackSupervisor.java
boolean resumeHomeStackTask(int homeStackTaskType, ActivityRecord prev, String reason) {
···
// Only resume home activity if isn't finishing.
if (r != null && !r.finishing) {
mService.setFocusedActivityLocked(r, myReason);
return resumeFocusedStackTopActivityLocked(mHomeStack, prev, null);
}
return mService.startHomeActivityLocked(mCurrentUser, myReason);
}
resumeHomeStackTask最后调用ActivityManagerService.java的startHomeActivityLocked函数
frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java
String mTopAction = Intent.ACTION_MAIN;
boolean startHomeActivityLocked(int userId, String reason) {
//
if (mFactoryTest == FactoryTest.FACTORY_TEST_LOW_LEVEL
&& mTopAction == null) {
// We are running in factory test mode, but unable to find
// the factory test app, so just sit around displaying the
// error message and don't try to start anything.
return false;
}
//创建要启动的Intent
Intent intent = getHomeIntent();
ActivityInfo aInfo = resolveActivityInfo(intent, STOCK_PM_FLAGS, userId);
if (aInfo != null) {
intent.setComponent(new ComponentName(aInfo.applicationInfo.packageName, aInfo.name));
// Don't do this if the home app is currently being
// instrumented.
aInfo = new ActivityInfo(aInfo);
aInfo.applicationInfo = getAppInfoForUser(aInfo.applicationInfo, userId);
ProcessRecord app = getProcessRecordLocked(aInfo.processName,
aInfo.applicationInfo.uid, true);
//判断符合Action为Intent.ACTION_MAIN，Category为Intent.CATEGORY_HOME的应用程序是否已经启动
if (app == null || app.instrumentationClass == null) {
intent.setFlags(intent.getFlags() | Intent.FLAG_ACTIVITY_NEW_TASK);
//启动Intent
mActivityStarter.startHomeActivityLocked(intent, aInfo, reason);
}
} else {
Slog.wtf(TAG, "No home screen found for " + intent, new Throwable());
}
return true;
}
//创建Intent
Intent getHomeIntent() {
Intent intent = new Intent(mTopAction, mTopData != null ? Uri.parse(mTopData) : null);
intent.setComponent(mTopComponent);
intent.addFlags(Intent.FLAG_DEBUG_TRIAGED_MISSING);
if (mFactoryTest != FactoryTest.FACTORY_TEST_LOW_LEVEL) {
//表示Lanucher
intent.addCategory(Intent.CATEGORY_HOME);
}
return intent;
}ActivityManagerService.java的startHomeActivityLocked方法最终完成Lanucher的启动
- 如何系统运行模式是低级工厂模式并且mTpoicAction为null，则退出方法，否则进行下面的处理
- 创建Intent，如果系统模式不是低级工厂模式，则将intent的Category设置为Intent.CATEGORY_HOME
- 判断符合Action为Intent.ACTION_MAIN，Category为Intent.CATEGORY_HOME的应用程序是否已经启动
- 如果没有启动则启动该应用程序，就是Launcher程序。
Launcher3的AndroidManifest.xml配置文件中的intent-filter匹配Action为android.intent.action.MAIN，Category为android.intent.category.HOME。如下所示
packages/apps/Launcher3/AndroidManifest.xml
<manifest
xmlns:android="http://schemas.android.com/apk/res/android"
package="com.android.launcher3">
<uses-sdk android:targetSdkVersion="23" android:minSdkVersion="16"/>
...
<application
...
<activity
android:name="com.android.launcher3.Launcher"
android:launchMode="singleTask"
android:clearTaskOnLaunch="true"
android:stateNotNeeded="true"
android:theme="@style/Theme"
android:windowSoftInputMode="adjustPan"
android:screenOrientation="nosensor"
android:configChanges="keyboard|keyboardHidden|navigation"
android:resumeWhilePausing="true"
android:taskAffinity=""
android:enabled="true">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.HOME" />
<category android:name="android.intent.category.DEFAULT" />
<category android:name="android.intent.category.MONKEY"/>
</intent-filter>
</activity>
...
</application>
</manifest>Lanucher应用图标显示过程
Lanucher3继承Activity，所以它的运行从onCreate方法开始
packages/apps/Launcher3/src/com/android/launcher3/Launcher.java
@Override
protected void onCreate(Bundle savedInstanceState) {
···
super.onCreate(savedInstanceState);
//1
LauncherAppState app = LauncherAppState.getInstance();
··· //2
mModel = app.setLauncher(this);
//3
if (!mModel.startLoader(mWorkspace.getRestorePage())) {
mDragLayer.setAlpha(0);
} else {
setWorkspaceLoading(true);
}
···
}
- 获取LauncherAppState的实例app
- 调用app的setLauncher函数并将Lanucher对象传入
- LanucherModel调用startLoader开始加载数据
LauncherAppState的setLauncher函数如下
packages/apps/Launcher3/src/com/android/launcher3/LauncherAppState.java
LauncherModel setLauncher(Launcher launcher) {
getLauncherProvider().setLauncherProviderChangeListener(launcher);
mModel.initialize(launcher);//1
mAccessibilityDelegate = ((launcher != null) && Utilities.ATLEAST_LOLLIPOP) ?
new LauncherAccessibilityDelegate(launcher) : null;
return mModel;
}
public void initialize(Callbacks callbacks) {
synchronized (mLock) {
unbindItemInfosAndClearQueuedBindRunnables();
mCallbacks = new WeakReference<Callbacks>(callbacks);
}
}initialize函数中将callbacks封装成一个弱引用对象，这个mCallbacks对象就是传入的launcher对象，下面将会用到它。
接下来回到LauncherModel的startLoader函数
packages/apps/Launcher3/src/com/android/launcher3/LauncherModel.java
// 创建了具有消息循环的线程HandlerThread对象
@Thunk static final HandlerThread sWorkerThread = new HandlerThread("launcher-loader");
static {
sWorkerThread.start();
}
// 创建了Handler，并且传入HandlerThread的Looper。Hander的作用就是向HandlerThread发送消息
@Thunk static final Handler sWorker = new Handler(sWorkerThread.getLooper());
public boolean startLoader(int synchronousBindPage) {
// Enable queue before starting loader. It will get disabled in Launcher#finishBindingItems
InstallShortcutReceiver.enableInstallQueue();
synchronized (mLock) {
// Don't bother to start the thread if we know it's not going to do anything
if (mCallbacks != null && mCallbacks.get() != null) {
final Callbacks oldCallbacks = mCallbacks.get();
// Clear any pending bind-runnables from the synchronized load process.
runOnMainThread(new Runnable() {
public void run() {
oldCallbacks.clearPendingBinds();
}
});
// If there is already one running, tell it to stop.
stopLoaderLocked();
// 创建LoaderTask
mLoaderTask = new LoaderTask(mApp.getContext(), synchronousBindPage);
// TODO: mDeepShortcutsLoaded does not need to be true for synchronous bind.
if (synchronousBindPage != PagedView.INVALID_RESTORE_PAGE && mAllAppsLoaded
&& mWorkspaceLoaded && mDeepShortcutsLoaded && !mIsLoaderTaskRunning) {
mLoaderTask.runBindSynchronousPage(synchronousBindPage);
return true;
} else {
sWorkerThread.setPriority(Thread.NORM_PRIORITY);
// 将LoaderTask作为消息发送给HandlerThread
sWorker.post(mLoaderTask);
}
}
}
return false;
}
- 创建LoadTask对象
- 将LoadTask对象作为消息发送到HandlerThread处理，sWorkerThread是具有消息循环的线程HandlerThread对象，sWorker是一个Handler对象，并且传入了sWorkerThread的Looper，所以sWorker发送的消息将由sWorkerThread处理。
LoaderTask实现了Runnable接口，当它被处理时会调用run方法。
packages/apps/Launcher3/src/com/android/launcher3/LauncherModel.java
private class LoaderTask implements Runnable {
···
public void run() {
synchronized (mLock) {
if (mStopped) {
return;
}
mIsLoaderTaskRunning = true;
}
keep_running: {
//step 1: 加载工作区信息
loadAndBindWorkspace();
if (mStopped) {
break keep_running;
}
waitForIdle();
//step 2: 加载系统已经安装的应用程序信息
loadAndBindAllApps();
waitForIdle();
//step 3: loading deep shortcuts
loadAndBindDeepShortcuts();
}
···
}
···
}
- loadAndBindWorkspace方法加载工作区信息
- loadAndBindAllApps方法加载系统以及安装的应用程序
loadAndBindAllApps方法的实现如下：
private void loadAndBindAllApps() {
if (DEBUG_LOADERS) {
Log.d(TAG, "loadAndBindAllApps mAllAppsLoaded=" + mAllAppsLoaded);
}
if (!mAllAppsLoaded) {
//如果系统没有加载已经安装的应用程序信息，则加载所有应用
loadAllApps();
synchronized (LoaderTask.this) {
if (mStopped) {
return;
}
}
updateIconCache();
synchronized (LoaderTask.this) {
if (mStopped) {
return;
}
mAllAppsLoaded = true;
}
} else {
onlyBindAllApps();
}
}loadAllApps方法如下
private void loadAllApps() {
···
//就是获取Launcher对象
final Callbacks oldCallbacks = mCallbacks.get();
final ArrayList<AppInfo> added = mBgAllAppsList.added;
mBgAllAppsList.added = new ArrayList<AppInfo>();
// Post callback on main thread
mHandler.post(new Runnable() {
public void run() {
final long bindTime = SystemClock.uptimeMillis();
final Callbacks callbacks = tryGetCallbacks(oldCallbacks);
if (callbacks != null) {
//
callbacks.bindAllApplications(added);
if (DEBUG_LOADERS) {
Log.d(TAG, "bound " + added.size() + " apps in "
+ (SystemClock.uptimeMillis() - bindTime) + "ms");
}
} else {
Log.i(TAG, "not binding apps: no Launcher activity");
}
}
});
···
}
callbacks对象事件上就是Launcher对象，callbacks.bindAllApplications就是调用Launcher的bindAllApplications方法。
packages/apps/Launcher3/src/com/android/launcher3/Launcher.java
/**
* Add the icons for all apps.
*
* Implementation of the method from LauncherModel.Callbacks.
*/
public void bindAllApplications(final ArrayList<AppInfo> apps) {
if (waitUntilResume(mBindAllApplicationsRunnable, true)) {
mTmpAppsList = apps;
return;
}
if (mAppsView != null) {
//传入App列表数据
mAppsView.setApps(apps);
}
if (mLauncherCallbacks != null) {
mLauncherCallbacks.bindAllApplications(apps);
}
}packages/apps/Launcher3/src/com/android/launcher3/allapps/AllAppsContainerView.java
public void setApps(List<AppInfo> apps) {
mApps.setApps(apps);
} @Override
protected void onFinishInflate() {
super.onFinishInflate();
// Load the all apps recycler view
mAppsRecyclerView = (AllAppsRecyclerView) findViewById(R.id.apps_list_view);
mAppsRecyclerView.setApps(mApps);
//GridLayoutManager
mAppsRecyclerView.setLayoutManager(mLayoutManager);
//AllAppsGridAdapter
mAppsRecyclerView.setAdapter(mAdapter);
mAppsRecyclerView.setHasFixedSize(true);
mAppsRecyclerView.addOnScrollListener(mElevationController);
mAppsRecyclerView.setElevationController(mElevationController);
if (mItemDecoration != null) {
mAppsRecyclerView.addItemDecoration(mItemDecoration);
}
FocusedItemDecorator focusedItemDecorator = new FocusedItemDecorator(mAppsRecyclerView);
mAppsRecyclerView.addItemDecoration(focusedItemDecorator);
mAppsRecyclerView.preMeasureViews(mAdapter);
mAdapter.setIconFocusListener(focusedItemDecorator.getFocusListener());
}onFinishInflate函数在加载完xml文件时就会调用，AllAppsRecyclerView将显示App列表,这样应用程序的图标就会显示在屏幕上。
Launcher应用图标点击过程
下面开始了解在Launcher上点击一个应用图标的过程。
Lanucher的xml布局文件会加载AllAppsContainerView这个控件如下：
packages/apps/Launcher3/src/com/android/launcher3/allapps/AllAppsContainerView.java
public AllAppsContainerView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
Resources res = context.getResources();
//1
mLauncher = Launcher.getLauncher(context);
mSectionNamesMargin = res.getDimensionPixelSize(R.dimen.all_apps_grid_view_start_margin);
mApps = new AlphabeticalAppsList(context);
//2
mAdapter = new AllAppsGridAdapter(mLauncher, mApps, mLauncher, this);
mApps.setAdapter(mAdapter);
mLayoutManager = mAdapter.getLayoutManager();
mItemDecoration = mAdapter.getItemDecoration();
DeviceProfile grid = mLauncher.getDeviceProfile();
if (FeatureFlags.LAUNCHER3_ALL_APPS_PULL_UP && !grid.isVerticalBarLayout()) {
mRecyclerViewBottomPadding = 0;
setPadding(0, 0, 0, 0);
} else {
mRecyclerViewBottomPadding =
res.getDimensionPixelSize(R.dimen.all_apps_list_bottom_padding);
}
mSearchQueryBuilder = new SpannableStringBuilder();
Selection.setSelection(mSearchQueryBuilder, 0);
}- 获取Launcher的实例
- 创建AllAppsGridAdapter的实例，并传入Launcher对象
接下来看AllAppsGridAdapter，它是RecyclerView的Adapter，直接看它的onCreateViewHolder方法。
packages/apps/Launcher3/src/com/android/launcher3/allapps/AllAppsGridAdapter.java
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
switch (viewType) {
case VIEW_TYPE_SECTION_BREAK:
return new ViewHolder(new View(parent.getContext()));
case VIEW_TYPE_ICON:
/* falls through */
case VIEW_TYPE_PREDICTION_ICON: {
//1
BubbleTextView icon = (BubbleTextView) mLayoutInflater.inflate(
R.layout.all_apps_icon, parent, false);
//2
icon.setOnClickListener(mIconClickListener);
icon.setOnLongClickListener(mIconLongClickListener);
icon.setLongPressTimeout(ViewConfiguration.get(parent.getContext())
.getLongPressTimeout());
icon.setOnFocusChangeListener(mIconFocusListener);
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
switch (holder.getItemViewType()) {
case VIEW_TYPE_ICON: {
AppInfo info = mApps.getAdapterItems().get(position).appInfo;
BubbleTextView icon = (BubbleTextView) holder.mContent;
//3
icon.applyFromApplicationInfo(info);
icon.setAccessibilityDelegate(mLauncher.getAccessibilityDelegate());
break;
}
}- 实例化BubbleTextView就是Launcher上的应用程序图标控件
- BubbleTextView设置点击事件，mIconClickListener就是传入的Launcher对象，所有点击应用图标就会回调Launcher的onClick方法
- 给BubbleTextView设置tag为AppInfo
下面看Launcher.java的onClick方法：
packages/apps/Launcher3/src/com/android/launcher3/Launcher.java
public void onClick(View v) {
···
Object tag = v.getTag();
//ShortcutInfo
if (tag instanceof ShortcutInfo) {
onClickAppShortcut(v);
//AppInfo
} else if (tag instanceof AppInfo) {
startAppShortcutOrInfoActivity(v);
}
···
}当tag是AppInfo时调用startAppShortcutOrInfoActivity方法
private void startAppShortcutOrInfoActivity(View v) {
ItemInfo item = (ItemInfo) v.getTag();
Intent intent = item.getIntent();
if (intent == null) {
throw new IllegalArgumentException("Input must have a valid intent");
}
//
boolean success = startActivitySafely(v, intent, item);
getUserEventDispatcher().logAppLaunch(v, intent);
}startAppShortcutOrInfoActivity调用startActivitySafely来启动应用程序。
public boolean startActivitySafely(View v, Intent intent, ItemInfo item) {
···
// Prepare intent
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
if (v != null) {
intent.setSourceBounds(getViewBounds(v));
}
try {
if (Utilities.ATLEAST_MARSHMALLOW && item != null
&& (item.itemType == Favorites.ITEM_TYPE_SHORTCUT
|| item.itemType == Favorites.ITEM_TYPE_DEEP_SHORTCUT)
&& ((ShortcutInfo) item).promisedIntent == null) {
// Shortcuts need some special checks due to legacy reasons.
startShortcutIntentSafely(intent, optsBundle, item);
} else if (user == null || user.equals(UserHandleCompat.myUserHandle())) {
// Could be launching some bookkeeping activity
startActivity(intent, optsBundle);
} else {
LauncherAppsCompat.getInstance(this).startActivityForProfile(
intent.getComponent(), user, intent.getSourceBounds(), optsBundle);
}
return true;
} catch (ActivityNotFoundException|SecurityException e) {
Toast.makeText(this, R.string.activity_not_found, Toast.LENGTH_SHORT).show();
Log.e(TAG, "Unable to launch. tag=" + item + " intent=" + intent, e);
}
return false;
}