文章目录
- 一、 Service 中的 getApplication() 方法分析
- 二、 ActivityThread 中的 H 处理 CREATE_SERVICE 消息
- 三、 ActivityThread 中的 handleCreateService 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、 Service 中的 getApplication() 方法分析
在 Service 中调用 getApplication() 方法 , 获取 Application , 返回的是 Service 中的 private Application mApplication 成员 , 该成员在 Service 的 attach 方法中进行设置 ;
public abstract class Service extends ContextWrapper implements ComponentCallbacks2 {
// ------------------ Internal API ------------------
/**
* @hide
*/
@UnsupportedAppUsage
public final void attach(
Context context,
ActivityThread thread, String className, IBinder token,
Application application, Object activityManager) {
attachBaseContext(context);
mThread = thread; // NOTE: unused - remove?
mClassName = className;
mToken = token;
mApplication = application;
mActivityManager = (IActivityManager)activityManager;
mStartCompatibility = getApplicationInfo().targetSdkVersion
< Build.VERSION_CODES.ECLAIR;
}
@UnsupportedAppUsage
private Application mApplication = null;
/** Return the application that owns this service. */
public final Application getApplication() {
return mApplication;
}
}
二、 ActivityThread 中的 H 处理 CREATE_SERVICE 消息
在 ActivityThread 中 , 创建并启动一个 Service , H ( Handler 子类 ) 接到一个 CREATE_SERVICE 消息 , 在相应的处理该 CREATE_SERVICE 消息的 handleMessage 方法中 , 调用了 handleCreateService 方法 ;
public final class ActivityThread {
private class H extends Handler {
public static final int CREATE_SERVICE = 114;
public void handleMessage(Message msg) {
if (DEBUG_MESSAGES) Slog.v(TAG, ">>> handling: " + codeToString(msg.what));
switch (msg.what) {
case CREATE_SERVICE:
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, ("serviceCreate: " + String.valueOf(msg.obj)));
handleCreateService((CreateServiceData)msg.obj);
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 handleCreateService 方法
handleCreateService 方法中直接创建了 Service 组件 ,
// ★ 创建 Service
service = (Service) cl.loadClass(data.info.name).newInstance();
并调用了 Service 组件的 attach 方法 ,
// ★ 调用了 Service 的 attach 方法
service.attach(context, this, data.info.name, data.token, app,
ActivityManager.getService());
在 Service 组件的 attach 方法的第 5 个参数 app 就是设置的 Application , app 的创建代码如下 ,
Application app = packageInfo.makeApplication(false, mInstrumentation);
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 ;
主要源码 :
public final class ActivityThread {
private class H extends Handler {
public static final int LAUNCH_ACTIVITY = 100;
public static final int CREATE_SERVICE = 114;
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;
case CREATE_SERVICE:
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, ("serviceCreate: " + String.valueOf(msg.obj)));
handleCreateService((CreateServiceData)msg.obj);
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;
}
// ★ 创建 Service 组件
private void handleCreateService(CreateServiceData data) {
LoadedApk packageInfo = getPackageInfoNoCheck(
data.info.applicationInfo, data.compatInfo);
Service service = null;
try {
java.lang.ClassLoader cl = packageInfo.getClassLoader();
// ★ 创建 Service
service = (Service) cl.loadClass(data.info.name).newInstance();
} catch (Exception e) {}
try {
ContextImpl context = ContextImpl.createAppContext(this, packageInfo);
context.setOuterContext(service);
Application app = packageInfo.makeApplication(false, mInstrumentation);
// ★ 调用了 Service 的 attach 方法
service.attach(context, this, data.info.name, data.token, app,
ActivityManager.getService());
service.onCreate();
} catch (Exception e) {}
}
}
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 Service 组件中获取的 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 :
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 static final int CREATE_SERVICE = 114;
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;
case CREATE_SERVICE:
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, ("serviceCreate: " + String.valueOf(msg.obj)));
handleCreateService((CreateServiceData)msg.obj);
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;
}
// ★ 创建 Service 组件
private void handleCreateService(CreateServiceData data) {
// If we are getting ready to gc after going to the background, well
// we are back active so skip it.
unscheduleGcIdler();
LoadedApk packageInfo = getPackageInfoNoCheck(
data.info.applicationInfo, data.compatInfo);
Service service = null;
try {
java.lang.ClassLoader cl = packageInfo.getClassLoader();
// ★ 创建 Service
service = (Service) cl.loadClass(data.info.name).newInstance();
} catch (Exception e) {
if (!mInstrumentation.onException(service, e)) {
throw new RuntimeException(
"Unable to instantiate service " + data.info.name
+ ": " + e.toString(), e);
}
}
try {
if (localLOGV) Slog.v(TAG, "Creating service " + data.info.name);
ContextImpl context = ContextImpl.createAppContext(this, packageInfo);
context.setOuterContext(service);
Application app = packageInfo.makeApplication(false, mInstrumentation);
// ★ 调用了 Service 的 attach 方法
service.attach(context, this, data.info.name, data.token, app,
ActivityManager.getService());
service.onCreate();
mServices.put(data.token, service);
try {
ActivityManager.getService().serviceDoneExecuting(
data.token, SERVICE_DONE_EXECUTING_ANON, 0, 0);
} catch (RemoteException e) {
throw e.rethrowFromSystemServer();
}
} catch (Exception e) {
if (!mInstrumentation.onException(service, e)) {
throw new RuntimeException(
"Unable to create service " + data.info.name
+ ": " + e.toString(), e);
}
}
}
}
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 ;
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 :
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
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