文章目录
- 一、 Activity 中的 getApplication() 方法分析
- 二、 ActivityThread 中的 H 处理 消息及 handleLaunchActivity 方法操作
- 三、 ActivityThread 中的 performLaunchActivity 方法
- 四、 LoadedApk 中的 mApplication 成员
- 五、 ActivityThread 涉及源码
- 六、 Instrumentation 涉及源码
- 七、 LoadedApk 涉及源码
一、 Activity 中的 getApplication() 方法分析
在 Activity 中调用 getApplication() 方法 , 获取 Application 的过程分析 ;
下面就是调用的 Activity 的 getApplication() 方法 , 其获取的是 Application mApplication 成员 ;
而 mApplication 成员是在 attach() 方法中赋值的 ;
代码语言：javascript复制public class Activity extends ContextThemeWrapper
implements LayoutInflater.Factory2,
Window.Callback, KeyEvent.Callback,
OnCreateContextMenuListener, ComponentCallbacks2,
Window.OnWindowDismissedCallback, WindowControllerCallback,
AutofillManager.AutofillClient, ContentCaptureManager.ContentCaptureClient {
@UnsupportedAppUsage
private Application mApplication;
/** Return the application that owns this activity. */
public final Application getApplication() {
return mApplication;
}
@UnsupportedAppUsage
final void attach(Context context, ActivityThread aThread,
Instrumentation instr, IBinder token, int ident,
Application application, Intent intent, ActivityInfo info,
CharSequence title, Activity parent, String id,
NonConfigurationInstances lastNonConfigurationInstances,
Configuration config, String referrer, IVoiceInteractor voiceInteractor,
Window window, ActivityConfigCallback activityConfigCallback, IBinder assistToken) {
attachBaseContext(context);
mApplication = application;
}
}参考源码路径 : frameworks/base/core/java/android/app/Activity.java
二、 ActivityThread 中的 H 处理 消息及 handleLaunchActivity 方法操作
在 ActivityThread 中 , 创建并启动一个 Activity , H ( Handler 子类 ) 接到一个 LAUNCH_ACTIVITY 消息 , 在相应的处理该 LAUNCH_ACTIVITY 消息的 handleMessage 方法中 , 调用了 handleLaunchActivity 方法 ;
代码语言：javascript复制public final class ActivityThread {
private class H extends Handler {
public static final int LAUNCH_ACTIVITY = 100;
public void handleMessage(Message msg) {
if (DEBUG_MESSAGES) Slog.v(TAG, ">>> handling: " codeToString(msg.what));
switch (msg.what) {
case LAUNCH_ACTIVITY: {
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "activityStart");
final ActivityClientRecord r = (ActivityClientRecord) msg.obj;
r.packageInfo = getPackageInfoNoCheck(
r.activityInfo.applicationInfo, r.compatInfo);
// ★ 调用 handleLaunchActivity 方法处理该消息
handleLaunchActivity(r, null, "LAUNCH_ACTIVITY");
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
} break;
} // switch
} // handleMessage
} // private class H extends Handler
}参考路径 : frameworks/base/core/java/android/app/ActivityThread.java
三、 ActivityThread 中的 performLaunchActivity 方法
handleLaunchActivity 方法中调用了 performLaunchActivity 方法 , 在该方法中通过 mInstrumentation.newActivity 创建 Activity , Instrumentation 创建 Activity 是通过反射进行的 ;
performLaunchActivity 方法中创建了 Activity 后 , 就调用了 Activity 的 attach 方法 , 为 Activity 中的 Application mApplication 成员赋值 ;
代码语言：javascript复制 activity.attach(appContext, this, getInstrumentation(), r.token,
r.ident, app, r.intent, r.activityInfo, title, r.parent,
r.embeddedID, r.lastNonConfigurationInstances, config,
r.referrer, r.voiceInteractor, window, r.configCallback);在调用的 activity.attach 中第六个参数 app 就是设置的 Application , app 的创建代码如下 , 这里是传入 Activity attach 方法中的 Application , 赋值给 Activity 中的 mApplication 成员 , packageInfo 就是 LoadedApk , LoadedApk 的 makeApplication 直接使用的就是 LoadedApk 中的 mApplication 成员 ;
代码语言：javascript复制Application app = r.packageInfo.makeApplication(false, mInstrumentation);主要源码 :
代码语言：javascript复制public final class ActivityThread {
private class H extends Handler {
public static final int LAUNCH_ACTIVITY = 100;
public void handleMessage(Message msg) {
if (DEBUG_MESSAGES) Slog.v(TAG, ">>> handling: " codeToString(msg.what));
switch (msg.what) {
case LAUNCH_ACTIVITY: {
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "activityStart");
final ActivityClientRecord r = (ActivityClientRecord) msg.obj;
r.packageInfo = getPackageInfoNoCheck(
r.activityInfo.applicationInfo, r.compatInfo);
// ★ 调用 handleLaunchActivity 方法处理该消息
handleLaunchActivity(r, null, "LAUNCH_ACTIVITY");
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
} break;
} // switch
} // handleMessage
} // private class H extends Handler
private void handleLaunchActivity(ActivityClientRecord r, Intent customIntent, String reason) {
// ★ 此处创建了一个 Activity
Activity a = performLaunchActivity(r, customIntent);
}
private Activity performLaunchActivity(ActivityClientRecord r, Intent customIntent) {
// System.out.println("##### [" System.currentTimeMillis() "] ActivityThread.performLaunchActivity(" r ")");
ActivityInfo aInfo = r.activityInfo;
ContextImpl appContext = createBaseContextForActivity(r);
// ★ 声明 Activity
Activity activity = null;
try {
java.lang.ClassLoader cl = appContext.getClassLoader();
// ★ 创建 Activity , 与创建 Application 类似
activity = mInstrumentation.newActivity(
cl, component.getClassName(), r.intent);
} catch (Exception e) {
}
try {
// ★ 这里是传入 Activity attach 方法中的 Application , 赋值给 Activity 中的 mApplication 成员
Application app = r.packageInfo.makeApplication(false, mInstrumentation);
if (activity != null) {
appContext.setOuterContext(activity);
// ★ 此处调用了 Activity 的 attach 方法 , 给 Activity 中的 mApplication 成员赋值
activity.attach(appContext, this, getInstrumentation(), r.token,
r.ident, app, r.intent, r.activityInfo, title, r.parent,
r.embeddedID, r.lastNonConfigurationInstances, config,
r.referrer, r.voiceInteractor, window, r.configCallback);
return activity;
}
}参考路径 : frameworks/base/core/java/android/app/ActivityThread.java
四、 LoadedApk 中的 mApplication 成员
LoadedApk 中的 mApplication 成员已经替换成了自定义的 Application , 不再是代理的 Application , 因此从 Activity 中获取的 Application 是已经替换后的用户自定义的 Application , 不是代理 Application ;
Application 已经执行完毕 , Application 替换操作是在 Application 的 onCreate 方法中执行的 , 此处的 Activity 执行肯定在 Application 创建完毕之后执行的 ;
主要源码 :
代码语言：javascript复制public final class LoadedApk {
public Application makeApplication(boolean forceDefaultAppClass,
Instrumentation instrumentation) {
// ★ 如果之前创建过 Application , 就直接使用
if (mApplication != null) {
return mApplication;
}
}
}参考路径 : frameworks/base/core/java/android/app/LoadedApk.java
五、 ActivityThread 涉及源码
public final class ActivityThread {
private class H extends Handler {
public static final int LAUNCH_ACTIVITY = 100;
public void handleMessage(Message msg) {
if (DEBUG_MESSAGES) Slog.v(TAG, ">>> handling: " codeToString(msg.what));
switch (msg.what) {
case LAUNCH_ACTIVITY: {
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "activityStart");
final ActivityClientRecord r = (ActivityClientRecord) msg.obj;
r.packageInfo = getPackageInfoNoCheck(
r.activityInfo.applicationInfo, r.compatInfo);
// ★ 调用 handleLaunchActivity 方法处理该消息
handleLaunchActivity(r, null, "LAUNCH_ACTIVITY");
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
} break;
} // switch
} // handleMessage
} // private class H extends Handler
private void handleLaunchActivity(ActivityClientRecord r, Intent customIntent, String reason) {
// If we are getting ready to gc after going to the background, well
// we are back active so skip it.
unscheduleGcIdler();
mSomeActivitiesChanged = true;
if (r.profilerInfo != null) {
mProfiler.setProfiler(r.profilerInfo);
mProfiler.startProfiling();
}
// Make sure we are running with the most recent config.
handleConfigurationChanged(null, null);
if (localLOGV) Slog.v(
TAG, "Handling launch of " r);
// Initialize before creating the activity
WindowManagerGlobal.initialize();
// ★ 此处创建了一个 Activity
Activity a = performLaunchActivity(r, customIntent);
if (a != null) {
r.createdConfig = new Configuration(mConfiguration);
reportSizeConfigurations(r);
Bundle oldState = r.state;
handleResumeActivity(r.token, false, r.isForward,
!r.activity.mFinished && !r.startsNotResumed, r.lastProcessedSeq, reason);
if (!r.activity.mFinished && r.startsNotResumed) {
// The activity manager actually wants this one to start out paused, because it
// needs to be visible but isn't in the foreground. We accomplish this by going
// through the normal startup (because activities expect to go through onResume()
// the first time they run, before their window is displayed), and then pausing it.
// However, in this case we do -not- need to do the full pause cycle (of freezing
// and such) because the activity manager assumes it can just retain the current
// state it has.
performPauseActivityIfNeeded(r, reason);
// We need to keep around the original state, in case we need to be created again.
// But we only do this for pre-Honeycomb apps, which always save their state when
// pausing, so we can not have them save their state when restarting from a paused
// state. For HC and later, we want to (and can) let the state be saved as the
// normal part of stopping the activity.
if (r.isPreHoneycomb()) {
r.state = oldState;
}
}
} else {
// If there was an error, for any reason, tell the activity manager to stop us.
try {
ActivityManager.getService()
.finishActivity(r.token, Activity.RESULT_CANCELED, null,
Activity.DONT_FINISH_TASK_WITH_ACTIVITY);
} catch (RemoteException ex) {
throw ex.rethrowFromSystemServer();
}
}
}
private Activity performLaunchActivity(ActivityClientRecord r, Intent customIntent) {
// System.out.println("##### [" System.currentTimeMillis() "] ActivityThread.performLaunchActivity(" r ")");
ActivityInfo aInfo = r.activityInfo;
if (r.packageInfo == null) {
r.packageInfo = getPackageInfo(aInfo.applicationInfo, r.compatInfo,
Context.CONTEXT_INCLUDE_CODE);
}
ComponentName component = r.intent.getComponent();
if (component == null) {
component = r.intent.resolveActivity(
mInitialApplication.getPackageManager());
r.intent.setComponent(component);
}
if (r.activityInfo.targetActivity != null) {
component = new ComponentName(r.activityInfo.packageName,
r.activityInfo.targetActivity);
}
ContextImpl appContext = createBaseContextForActivity(r);
// ★ 声明 Activity
Activity activity = null;
try {
java.lang.ClassLoader cl = appContext.getClassLoader();
// ★ 创建 Activity , 与创建 Application 类似
activity = mInstrumentation.newActivity(
cl, component.getClassName(), r.intent);
StrictMode.incrementExpectedActivityCount(activity.getClass());
r.intent.setExtrasClassLoader(cl);
r.intent.prepareToEnterProcess();
if (r.state != null) {
r.state.setClassLoader(cl);
}
} catch (Exception e) {
if (!mInstrumentation.onException(activity, e)) {
throw new RuntimeException(
"Unable to instantiate activity " component
": " e.toString(), e);
}
}
try {
// ★ 这里是传入 Activity attach 方法中的 Application , 赋值给 Activity 中的 mApplication 成员
Application app = r.packageInfo.makeApplication(false, mInstrumentation);
if (localLOGV) Slog.v(TAG, "Performing launch of " r);
if (localLOGV) Slog.v(
TAG, r ": app=" app
", appName=" app.getPackageName()
", pkg=" r.packageInfo.getPackageName()
", comp=" r.intent.getComponent().toShortString()
", dir=" r.packageInfo.getAppDir());
if (activity != null) {
CharSequence title = r.activityInfo.loadLabel(appContext.getPackageManager());
Configuration config = new Configuration(mCompatConfiguration);
if (r.overrideConfig != null) {
config.updateFrom(r.overrideConfig);
}
if (DEBUG_CONFIGURATION) Slog.v(TAG, "Launching activity "
r.activityInfo.name " with config " config);
Window window = null;
if (r.mPendingRemoveWindow != null && r.mPreserveWindow) {
window = r.mPendingRemoveWindow;
r.mPendingRemoveWindow = null;
r.mPendingRemoveWindowManager = null;
}
appContext.setOuterContext(activity);
// ★ 此处调用了 Activity 的 attach 方法 , 给 Activity 中的 mApplication 成员赋值
activity.attach(appContext, this, getInstrumentation(), r.token,
r.ident, app, r.intent, r.activityInfo, title, r.parent,
r.embeddedID, r.lastNonConfigurationInstances, config,
r.referrer, r.voiceInteractor, window, r.configCallback);
if (customIntent != null) {
activity.mIntent = customIntent;
}
r.lastNonConfigurationInstances = null;
checkAndBlockForNetworkAccess();
activity.mStartedActivity = false;
int theme = r.activityInfo.getThemeResource();
if (theme != 0) {
activity.setTheme(theme);
}
activity.mCalled = false;
if (r.isPersistable()) {
mInstrumentation.callActivityOnCreate(activity, r.state, r.persistentState);
} else {
mInstrumentation.callActivityOnCreate(activity, r.state);
}
if (!activity.mCalled) {
throw new SuperNotCalledException(
"Activity " r.intent.getComponent().toShortString()
" did not call through to super.onCreate()");
}
r.activity = activity;
r.stopped = true;
if (!r.activity.mFinished) {
activity.performStart();
r.stopped = false;
}
if (!r.activity.mFinished) {
if (r.isPersistable()) {
if (r.state != null || r.persistentState != null) {
mInstrumentation.callActivityOnRestoreInstanceState(activity, r.state,
r.persistentState);
}
} else if (r.state != null) {
mInstrumentation.callActivityOnRestoreInstanceState(activity, r.state);
}
}
if (!r.activity.mFinished) {
activity.mCalled = false;
if (r.isPersistable()) {
mInstrumentation.callActivityOnPostCreate(activity, r.state,
r.persistentState);
} else {
mInstrumentation.callActivityOnPostCreate(activity, r.state);
}
if (!activity.mCalled) {
throw new SuperNotCalledException(
"Activity " r.intent.getComponent().toShortString()
" did not call through to super.onPostCreate()");
}
}
}
r.paused = true;
mActivities.put(r.token, r);
} catch (SuperNotCalledException e) {
throw e;
} catch (Exception e) {
if (!mInstrumentation.onException(activity, e)) {
throw new RuntimeException(
"Unable to start activity " component
": " e.toString(), e);
}
}
return activity;
}
}参考路径 : frameworks/base/core/java/android/app/ActivityThread.java
六、 Instrumentation 涉及源码
Instrumentation 中创建 Activity 的 newActivity 方法 ;
代码语言：javascript复制public class Instrumentation {
/**
* Perform instantiation of an {@link Activity} object. This method is intended for use with
* unit tests, such as android.test.ActivityUnitTestCase. The activity will be useable
* locally but will be missing some of the linkages necessary for use within the system.
*
* @param clazz The Class of the desired Activity
* @param context The base context for the activity to use
* @param token The token for this activity to communicate with
* @param application The application object (if any)
* @param intent The intent that started this Activity
* @param info ActivityInfo from the manifest
* @param title The title, typically retrieved from the ActivityInfo record
* @param parent The parent Activity (if any)
* @param id The embedded Id (if any)
* @param lastNonConfigurationInstance Arbitrary object that will be
* available via {@link Activity#getLastNonConfigurationInstance()
* Activity.getLastNonConfigurationInstance()}.
* @return Returns the instantiated activity
* @throws InstantiationException
* @throws IllegalAccessException
*/
public Activity newActivity(Class<?> clazz, Context context,
IBinder token, Application application, Intent intent, ActivityInfo info,
CharSequence title, Activity parent, String id,
Object lastNonConfigurationInstance) throws InstantiationException,
IllegalAccessException {
Activity activity = (Activity)clazz.newInstance();
ActivityThread aThread = null;
activity.attach(context, aThread, this, token, 0 /* ident */, application, intent,
info, title, parent, id,
(Activity.NonConfigurationInstances)lastNonConfigurationInstance,
new Configuration(), null /* referrer */, null /* voiceInteractor */,
null /* window */, null /* activityConfigCallback */);
return activity;
}
}参考路径 : frameworks/base/core/java/android/app/Instrumentation.java
七、 LoadedApk 涉及源码
LoadedApk 中相关源码 :
代码语言：javascript复制public final class LoadedApk {
public Application makeApplication(boolean forceDefaultAppClass,
Instrumentation instrumentation) {
// ★ 如果之前创建过 Application , 就直接使用
if (mApplication != null) {
return mApplication;
}
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "makeApplication");
Application app = null;
String appClass = mApplicationInfo.className;
if (forceDefaultAppClass || (appClass == null)) {
appClass = "android.app.Application";
}
try {
java.lang.ClassLoader cl = getClassLoader();
if (!mPackageName.equals("android")) {
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER,
"initializeJavaContextClassLoader");
initializeJavaContextClassLoader();
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
}
ContextImpl appContext = ContextImpl.createAppContext(mActivityThread, this);
app = mActivityThread.mInstrumentation.newApplication(
cl, appClass, appContext);
appContext.setOuterContext(app);
} catch (Exception e) {
if (!mActivityThread.mInstrumentation.onException(app, e)) {
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
throw new RuntimeException(
"Unable to instantiate application " appClass
": " e.toString(), e);
}
}
mActivityThread.mAllApplications.add(app);
mApplication = app;
if (instrumentation != null) {
try {
instrumentation.callApplicationOnCreate(app);
} catch (Exception e) {
if (!instrumentation.onException(app, e)) {
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
throw new RuntimeException(
"Unable to create application " app.getClass().getName()
": " e.toString(), e);
}
}
}
// Rewrite the R 'constants' for all library apks.
SparseArray<String> packageIdentifiers = getAssets().getAssignedPackageIdentifiers();
final int N = packageIdentifiers.size();
for (int i = 0; i < N; i ) {
final int id = packageIdentifiers.keyAt(i);
if (id == 0x01 || id == 0x7f) {
continue;
}
rewriteRValues(getClassLoader(), packageIdentifiers.valueAt(i), id);
}
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
return app;
}
}参考路径 : frameworks/base/core/java/android/app/LoadedApk.java
