Android源码(3) --- 系统Launcher 启动流程

时间:2022-07-20 16:45:36

Launcher 启动流程

  • 1 启动Launcher
  • 在之前分析了一下SystemServer源码,最后启动boot/core/other … Service,在startOtherService 中,有调用到 mActivityManagerService.systemReady();
mActivityManagerService.systemReady(new Runnable() {
@Override
public void run() {
Slog.i(TAG, "Making services ready");
mSystemServiceManager.startBootPhase(
SystemService.PHASE_ACTIVITY_MANAGER_READY);
try { mActivityManagerService.startObservingNativeCrashes();
} catch (Throwable e) {
reportWtf("observing native crashes", e);
}

try {
startSystemUi(context);
} catch (Throwable e) {
reportWtf("starting System UI", e);
}
try {
if (networkScoreF != null) networkScoreF.systemReady();
} catch (Throwable e) {
reportWtf("making Network Score Service ready", e);
}
try {
if (networkManagementF != null) networkManagementF.systemReady();
} catch (Throwable e) {
reportWtf("making Network Managment Service ready", e);
}
try {
if (networkStatsF != null) networkStatsF.systemReady();
} catch (Throwable e) {
reportWtf("making Network Stats Service ready", e);
}
try {
if (networkPolicyF != null) networkPolicyF.systemReady();
} catch (Throwable e) {
reportWtf("making Network Policy Service ready", e);
}
try {
if (connectivityF != null) connectivityF.systemReady();
} catch (Throwable e) {
reportWtf("making Connectivity Service ready", e);
}
try {
if (audioServiceF != null) audioServiceF.systemReady();
} catch (Throwable e) {
reportWtf("Notifying AudioService running", e);
}
Watchdog.getInstance().start();
}
});
}
  • 通过源码可以看到其中大多是系统服务systemReady()操作,重点关注一下Launcher所进行的操作流程,ActivityManagerService.systemReady();
public void systemReady(final Runnable goingCallback) {
...... 各种校验 System ready 情况 ......
Slog.i(TAG, "System now ready");

// Make sure we have no pre-ready processes sitting around.


retrieveSettings();
loadResourcesOnSystemReady();


// Start up initial activity.
mBooting = true;
startHomeActivityLocked(mCurrentUserId, "systemReady");

......
}
  • 这里主要是校验各种System ready 情况,最后调用startHomeActivityLocked();
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;
}
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);
if (app == null || app.instrumentationClass == null) {
intent.setFlags(intent.getFlags() | Intent.FLAG_ACTIVITY_NEW_TASK);
mStackSupervisor.startHomeActivity(intent, aInfo, reason);
}
}

return true;
}


Intent getHomeIntent() {
Intent intent = new Intent(mTopAction, mTopData != null ? Uri.parse(mTopData) : null);
intent.setComponent(mTopComponent);
if (mFactoryTest != FactoryTest.FACTORY_TEST_LOW_LEVEL) {
intent.addCategory(Intent.CATEGORY_HOME);
}
return intent;
}
  • 这里很清晰,先通过getHomeIntent获取 Intent之后,startHomeActivity进行start。而了Intent.CATEGORY_HOME常量是Android的androidmanifest.xml清单文件中的常量。
void startHomeActivity(Intent intent, ActivityInfo aInfo, String reason) {
moveHomeStackTaskToTop(HOME_ACTIVITY_TYPE, reason);
startActivityLocked(...);

if (inResumeTopActivity) {
scheduleResumeTopActivities();
}
}
  • 最后调用到的是startActivityLocked(),这里其实启动的是清单文件中声明的Launcher的Activity类

  • 2.LauncherActivity

  • LauncherActivity 继承自 ListActivity,layout 文件十分简单,一个ListView,一个TextView,从生命周期OnCreate()来看
protected void onCreate(Bundle icicle) {
super.onCreate(icicle);

mPackageManager = getPackageManager();

if (!mPackageManager.hasSystemFeature(PackageManager.FEATURE_WATCH)) {
requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
setProgressBarIndeterminateVisibility(true);
}
onSetContentView();

mIconResizer = new IconResizer();

mIntent = new Intent(getTargetIntent());
mIntent.setComponent(null);
mAdapter = new ActivityAdapter(mIconResizer);

setListAdapter(mAdapter);
getListView().setTextFilterEnabled(true);

updateAlertTitle();
updateButtonText();

if (!mPackageManager.hasSystemFeature(PackageManager.FEATURE_WATCH)) {
setProgressBarIndeterminateVisibility(false);
}
}


* 其中 getPackageManager() 是获取应用列表,以及应用信息,并将数据注入Adapter,显示到桌面。

protected void onListItemClick(ListView l, View v, int position, long id) {
Intent intent = intentForPosition(position);
startActivity(intent);
}

在点击图标的点击事件回调中,将Intent取出来后,并启动Activity.至此启动应用。Launcher 启动结束。