android - home键及launcher启动流程分析(二)
ut before it has actually
// started launching the initial applications), for us to complete our
// initialization.
ActivityManagerService.self().systemReady(new Runnable() {
public void run() {
Slog.i(TAG, "Making services ready");
核心代码如下:
[java]
public final class ActivityManagerService extends ActivityManagerNative
implements Watchdog.Monitor, BatteryStatsImpl.BatteryCallback {
......
public void systemReady(final Runnable goingCallback) {
......
synchronized (this) {
......
mMainStack.resumeTopActivityLocked(null);
}
}
......
}
4、ActivityStack.resumeTopActivityLocked
[java]
final boolean resumeTopActivityLocked(ActivityRecord prev, Bundle options) {
// Find the first activity that is not finishing.
ActivityRecord next = topRunningActivityLocked(null);
// Remember how we'll process this pause/resume situation, and ensure
// that the state is reset however we wind up proceeding.
final boolean userLeaving = mUserLeaving;
mUserLeaving = false;
if (next == null) {
// There are no more activities! Let's just start up the
// Launcher...
if (mMainStack) {
ActivityOptions.abort(options);
return mService.startHomeActivityLocked(mCurrentUser);
}
}
...
}
这里调用函数topRunningActivityLocked返回的是当前系统Activity堆栈最顶端的Activity，由于此时还没有
Activity被启动过，因此，返回值为null，即next变量的值为null，于是就调用mService.startHomeActivityLocked函数
5、startHomeActivityLocked
[java]
boolean startHomeActivityLocked(int userId) {
...
Intent intent = new Intent(
mTopAction,
mTopData != null Uri.parse(mTopData) : null);
intent.setComponent(mTopComponent);
if (mFactoryTest != SystemServer.FACTORY_TEST_LOW_LEVEL) {
intent.addCategory(Intent.CATEGORY_HOME);
}
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);
if (app == null || app.instrumentationClass == null) {
intent.setFlags(intent.getFlags() | Intent.FLAG_ACTIVITY_NEW_TASK);
mMainStack.startActivityLocked(null, intent, null, aInfo,
null, null, 0, 0, 0, 0, null, false, null);
}
}
return true;
}
函数首先创建一个CATEGORY_HOME类型的Intent，然后通过Intent.resolveActivityInfo函数向PackageManagerService
查询Category类型为HOME的Activity，即 packages/apps/Launcher2/AndroidManifest.xml文件中所示：
这里就是将拼装好的 home intent 发送出去即可
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