Android startActivity流程
1.常规调用
startActivity(new Intent(this,MainActivity.class));进入Activity的startActivity方法
/**
* Same as {@link #startActivity(Intent, Bundle)} with no options
* specified.
*
* @param intent The intent to start.
*
* @throws android.content.ActivityNotFoundException
*
* @see #startActivity(Intent, Bundle)
* @see #startActivityForResult
*/
@Override
public void startActivity(Intent intent) {
this.startActivity(intent, null);
}进入Activity的startActivityForResult方法
/**
* Launch a new activity. You will not receive any information about when
* the activity exits. This implementation overrides the base version,
* providing information about
* the activity performing the launch. Because of this additional
* information, the {@link Intent#FLAG_ACTIVITY_NEW_TASK} launch flag is not
* required; if not specified, the new activity will be added to the
* task of the caller.
*
* This method throws {@link android.content.ActivityNotFoundException}
* if there was no Activity found to run the given Intent.
*
* @param intent The intent to start.
* @param options Additional options for how the Activity should be started.
* See {@link android.content.Context#startActivity(Intent, Bundle)}
* Context.startActivity(Intent, Bundle)} for more details.
*
* @throws android.content.ActivityNotFoundException
*
* @see #startActivity(Intent)
* @see #startActivityForResult
*/
@Override
public void startActivity(Intent intent, @Nullable Bundle options) {
getAutofillClientController().onStartActivity(intent, mIntent);
if (options != null) {
startActivityForResult(intent, -1, options);
} else {
// Note we want to go through this call for compatibility with
// applications that may have overridden the method.
startActivityForResult(intent, -1);
}
}
/**
* Same as calling {@link #startActivityForResult(Intent, int, Bundle)}
* with no options.
*
* @param intent The intent to start.
* @param requestCode If >= 0, this code will be returned in
* onActivityResult() when the activity exits.
*
* @throws android.content.ActivityNotFoundException
*
* @see #startActivity
*/
public void startActivityForResult(@RequiresPermission Intent intent, int requestCode) {
startActivityForResult(intent, requestCode, null);
} /**
* Launch an activity for which you would like a result when it finished.
* When this activity exits, your
* onActivityResult() method will be called with the given requestCode.
* Using a negative requestCode is the same as calling
* {@link #startActivity} (the activity is not launched as a sub-activity).
*
* Note that this method should only be used with Intent protocols
* that are defined to return a result. In other protocols (such as
* {@link Intent#ACTION_MAIN} or {@link Intent#ACTION_VIEW}), you may
* not get the result when you expect. For example, if the activity you
* are launching uses {@link Intent#FLAG_ACTIVITY_NEW_TASK}, it will not
* run in your task and thus you will immediately receive a cancel result.
*
*
As a special case, if you call startActivityForResult() with a requestCode
* >= 0 during the initial onCreate(Bundle savedInstanceState)/onResume() of your
* activity, then your window will not be displayed until a result is
* returned back from the started activity. This is to avoid visible
* flickering when redirecting to another activity.
*
*
This method throws {@link android.content.ActivityNotFoundException}
* if there was no Activity found to run the given Intent.
*
* @param intent The intent to start.
* @param requestCode If >= 0, this code will be returned in
* onActivityResult() when the activity exits.
* @param options Additional options for how the Activity should be started.
* See {@link android.content.Context#startActivity(Intent, Bundle)}
* Context.startActivity(Intent, Bundle)} for more details.
*
* @throws android.content.ActivityNotFoundException
*
* @see #startActivity
*/
public void startActivityForResult(@RequiresPermission Intent intent, int requestCode,
@Nullable Bundle options) {
if (mParent == null) {
options = transferSpringboardActivityOptions(options);
Instrumentation.ActivityResult ar =
mInstrumentation.execStartActivity(
this, mMainThread.getApplicationThread(), mToken, this,
intent, requestCode, options);
if (ar != null) {
mMainThread.sendActivityResult(
mToken, mEmbeddedID, requestCode, ar.getResultCode(),
ar.getResultData());
}
if (requestCode >= 0) {
// If this start is requesting a result, we can avoid making
// the activity visible until the result is received. Setting
// this code during onCreate(Bundle savedInstanceState) or onResume() will keep the
// activity hidden during this time, to avoid flickering.
// This can only be done when a result is requested because
// that guarantees we will get information back when the
// activity is finished, no matter what happens to it.
mStartedActivity = true;
}
cancelInputsAndStartExitTransition(options);
// TODO Consider clearing/flushing other event sources and events for child windows.
} else {
if (options != null) {
mParent.startActivityFromChild(this, intent, requestCode, options);
} else {
// Note we want to go through this method for compatibility with
// existing applications that may have overridden it.
mParent.startActivityFromChild(this, intent, requestCode);
}
}
}
如果父activity不存在就调用
mInstrumentation.execStartActivity
如果父activity存在就调用
mParent.startActivityFromChild
mInstrumentation.execStartActivity会调用ATMS的
ActivityTaskManager.getService().startActivity
/**
* Execute a startActivity call made by the application. The default
* implementation takes care of updating any active {@link ActivityMonitor}
* objects and dispatches this call to the system activity manager; you can
* override this to watch for the application to start an activity, and
* modify what happens when it does.
*
* This method returns an {@link ActivityResult} object, which you can
* use when intercepting application calls to avoid performing the start
* activity action but still return the result the application is
* expecting. To do this, override this method to catch the call to start
* activity so that it returns a new ActivityResult containing the results
* you would like the application to see, and don't call up to the super
* class. Note that an application is only expecting a result if
* requestCode is >= 0.
*
*
This method throws {@link android.content.ActivityNotFoundException}
* if there was no Activity found to run the given Intent.
*
* @param who The Context from which the activity is being started.
* @param contextThread The main thread of the Context from which the activity
* is being started.
* @param token Internal token identifying to the system who is starting
* the activity; may be null.
* @param target Which activity is performing the start (and thus receiving
* any result); may be null if this call is not being made
* from an activity.
* @param intent The actual Intent to start.
* @param requestCode Identifier for this request's result; less than zero
* if the caller is not expecting a result.
* @param options Addition options.
*
* @return To force the return of a particular result, return an
* ActivityResult object containing the desired data; otherwise
* return null. The default implementation always returns null.
*
* @throws android.content.ActivityNotFoundException
*
* @see Activity#startActivity(Intent)
* @see Activity#startActivityForResult(Intent, int)
*
* {@hide}
*/
@UnsupportedAppUsage
public ActivityResult execStartActivity(
Context who, IBinder contextThread, IBinder token, Activity target,
Intent intent, int requestCode, Bundle options) {
IApplicationThread whoThread = (IApplicationThread) contextThread;
Uri referrer = target != null ? target.onProvideReferrer() : null;
if (referrer != null) {
intent.putExtra(Intent.EXTRA_REFERRER, referrer);
}
if (mActivityMonitors != null) {
synchronized (mSync) {
final int N = mActivityMonitors.size();
for (int i=0; i= 0 ? am.getResult() : null;
}
break;
}
}
}
}
try {
intent.migrateExtraStreamToClipData(who);
intent.prepareToLeaveProcess(who);
int result = ActivityTaskManager.getService().startActivity(whoThread,
who.getOpPackageName(), who.getAttributionTag(), intent,
intent.resolveTypeIfNeeded(who.getContentResolver()), token,
target != null ? target.mEmbeddedID : null, requestCode, 0, null, options);
checkStartActivityResult(result, intent);
} catch (RemoteException e) {
throw new RuntimeException("Failure from system", e);
}
return null;
}
mParent.startActivityFromChild内部调用的也是mInstrumentation.execStartActivity
/**
* This is called when a child activity of this one calls its
* {@link #startActivity} or {@link #startActivityForResult} method.
*
* This method throws {@link android.content.ActivityNotFoundException}
* if there was no Activity found to run the given Intent.
*
* @param child The activity making the call.
* @param intent The intent to start.
* @param requestCode Reply request code. < 0 if reply is not requested.
* @param options Additional options for how the Activity should be started.
* See {@link android.content.Context#startActivity(Intent, Bundle)}
* Context.startActivity(Intent, Bundle)} for more details.
*
* @throws android.content.ActivityNotFoundException
*
* @see #startActivity
* @see #startActivityForResult
* @deprecated Use {@code androidx.fragment.app.FragmentActivity#startActivityFromFragment(
* androidx.fragment.app.Fragment,Intent,int,Bundle)}
*/
@Deprecated
public void startActivityFromChild(@NonNull Activity child, @RequiresPermission Intent intent,
int requestCode, @Nullable Bundle options) {
options = transferSpringboardActivityOptions(options);
Instrumentation.ActivityResult ar =
mInstrumentation.execStartActivity(
this, mMainThread.getApplicationThread(), mToken, child,
intent, requestCode, options);
if (ar != null) {
mMainThread.sendActivityResult(
mToken, child.mEmbeddedID, requestCode,
ar.getResultCode(), ar.getResultData());
}
cancelInputsAndStartExitTransition(options);
}
framework/base/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
startActivity调用startActivityAsUser
@Override
public final int startActivity(IApplicationThread caller, String callingPackage,
String callingFeatureId, Intent intent, String resolvedType, IBinder resultTo,
String resultWho, int requestCode, int startFlags, ProfilerInfo profilerInfo,
Bundle bOptions) {
return startActivityAsUser(caller, callingPackage, callingFeatureId, intent, resolvedType,
resultTo, resultWho, requestCode, startFlags, profilerInfo, bOptions,
UserHandle.getCallingUserId());
}startActivityAsUser
@Override
public int startActivityAsUser(IApplicationThread caller, String callingPackage,
String callingFeatureId, Intent intent, String resolvedType, IBinder resultTo,
String resultWho, int requestCode, int startFlags, ProfilerInfo profilerInfo,
Bundle bOptions, int userId) {
return startActivityAsUser(caller, callingPackage, callingFeatureId, intent, resolvedType,
resultTo, resultWho, requestCode, startFlags, profilerInfo, bOptions, userId,
true /*validateIncomingUser*/);
}private int startActivityAsUser(IApplicationThread caller, String callingPackage,
@Nullable String callingFeatureId, Intent intent, String resolvedType,
IBinder resultTo, String resultWho, int requestCode, int startFlags,
ProfilerInfo profilerInfo, Bundle bOptions, int userId, boolean validateIncomingUser) {
assertPackageMatchesCallingUid(callingPackage);
enforceNotIsolatedCaller("startActivityAsUser");
userId = getActivityStartController().checkTargetUser(userId, validateIncomingUser,
Binder.getCallingPid(), Binder.getCallingUid(), "startActivityAsUser");
// TODO: Switch to user app stacks here.
return getActivityStartController().obtainStarter(intent, "startActivityAsUser")
.setCaller(caller)
.setCallingPackage(callingPackage)
.setCallingFeatureId(callingFeatureId)
.setResolvedType(resolvedType)
.setResultTo(resultTo)
.setResultWho(resultWho)
.setRequestCode(requestCode)
.setStartFlags(startFlags)
.setProfilerInfo(profilerInfo)
.setActivityOptions(bOptions)
.setUserId(userId)
.execute();
}获取：getActivityStartController().obtainStarter
ActivityStartController getActivityStartController() {
return mActivityStartController;
}ActivityStarter obtainStarter(Intent intent, String reason) {
return mFactory.obtain().setIntent(intent).setReason(reason);
}
/**
* Resolve necessary information according the request parameters provided earlier, and execute
* the request which begin the journey of starting an activity.
* @return The starter result.
*/
int execute() {
try {
// Refuse possible leaked file descriptors
if (mRequest.intent != null && mRequest.intent.hasFileDescriptors()) {
throw new IllegalArgumentException("File descriptors passed in Intent");
}
final LaunchingState launchingState;
synchronized (mService.mGlobalLock) {
final ActivityRecord caller = ActivityRecord.forTokenLocked(mRequest.resultTo);
final int callingUid = mRequest.realCallingUid == Request.DEFAULT_REAL_CALLING_UID
? Binder.getCallingUid() : mRequest.realCallingUid;
launchingState = mSupervisor.getActivityMetricsLogger().notifyActivityLaunching(
mRequest.intent, caller, callingUid);
}
// If the caller hasn't already resolved the activity, we're willing
// to do so here. If the caller is already holding the WM lock here,
// and we need to check dynamic Uri permissions, then we're forced
// to assume those permissions are denied to avoid deadlocking.
if (mRequest.activityInfo == null) {
mRequest.resolveActivity(mSupervisor);
}
// Add checkpoint for this shutdown or reboot attempt, so we can record the original
// intent action and package name.
if (mRequest.intent != null) {
String intentAction = mRequest.intent.getAction();
String callingPackage = mRequest.callingPackage;
if (intentAction != null && callingPackage != null
&& (Intent.ACTION_REQUEST_SHUTDOWN.equals(intentAction)
|| Intent.ACTION_SHUTDOWN.equals(intentAction)
|| Intent.ACTION_REBOOT.equals(intentAction))) {
ShutdownCheckPoints.recordCheckPoint(intentAction, callingPackage, null);
}
}
int res;
synchronized (mService.mGlobalLock) {
final boolean globalConfigWillChange = mRequest.globalConfig != null
&& mService.getGlobalConfiguration().diff(mRequest.globalConfig) != 0;
final Task rootTask = mRootWindowContainer.getTopDisplayFocusedRootTask();
if (rootTask != null) {
rootTask.mConfigWillChange = globalConfigWillChange;
}
ProtoLog.v(WM_DEBUG_CONFIGURATION, "Starting activity when config "
+ "will change = %b", globalConfigWillChange);
final long origId = Binder.clearCallingIdentity();
res = resolveToHeavyWeightSwitcherIfNeeded();
if (res != START_SUCCESS) {
return res;
}
res = executeRequest(mRequest);
Binder.restoreCallingIdentity(origId);
if (globalConfigWillChange) {
// If the caller also wants to switch to a new configuration, do so now.
// This allows a clean switch, as we are waiting for the current activity
// to pause (so we will not destroy it), and have not yet started the
// next activity.
mService.mAmInternal.enforceCallingPermission(
android.Manifest.permission.CHANGE_CONFIGURATION,
"updateConfiguration()");
if (rootTask != null) {
rootTask.mConfigWillChange = false;
}
ProtoLog.v(WM_DEBUG_CONFIGURATION,
"Updating to new configuration after starting activity.");
mService.updateConfigurationLocked(mRequest.globalConfig, null, false);
}
// The original options may have additional info about metrics. The mOptions is not
// used here because it may be cleared in setTargetRootTaskIfNeeded.
final ActivityOptions originalOptions = mRequest.activityOptions != null
? mRequest.activityOptions.getOriginalOptions() : null;
// If the new record is the one that started, a new activity has created.
final boolean newActivityCreated = mStartActivity == mLastStartActivityRecord;
// Notify ActivityMetricsLogger that the activity has launched.
// ActivityMetricsLogger will then wait for the windows to be drawn and populate
// WaitResult.
mSupervisor.getActivityMetricsLogger().notifyActivityLaunched(launchingState, res,
newActivityCreated, mLastStartActivityRecord, originalOptions);
if (mRequest.waitResult != null) {
mRequest.waitResult.result = res;
res = waitResultIfNeeded(mRequest.waitResult, mLastStartActivityRecord,
launchingState);
}
return getExternalResult(res);
}
} finally {
onExecutionComplete();
}
}
Android | Activity 启动流程分析 - 掘金 (juejin.cn)