上一篇介紹了apk啓動的流程到了創建activity的創建這裏接着繼續分析，先上圖片
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這裏從handleLaunchActivity方法繼續分析，如不明白的可以參考上一篇的分析android啓動流程分析，這邊直接就上代碼了
private void handleLaunchActivity(ActivityClientRecord r, Intent customIntent, String reason) {
......
Activity a = performLaunchActivity(r, customIntent);//創建activity
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);
......
} else {
......
}
}private Activity performLaunchActivity(ActivityClientRecord r, Intent customIntent) {
......
Activity activity = null;
try {
java.lang.ClassLoader cl = r.packageInfo.getClassLoader();
activity = mInstrumentation.newActivity(
cl, component.getClassName(), r.intent);//通過Instrumentation這個類創建Activity
......
} catch (Exception e) {
if (!mInstrumentation.onException(activity, e)) {
throw new RuntimeException(
"Unable to instantiate activity " + component
+ ": " + e.toString(), e);
}
}
......
activity.attach(appContext, this, getInstrumentation(), r.token,//attach方法
r.ident, app, r.intent, r.activityInfo, title, r.parent,
r.embeddedID, r.lastNonConfigurationInstances, config,
r.referrer, r.voiceInteractor, window);
......
int theme = r.activityInfo.getThemeResource();//設置主題
if (theme != 0) {
activity.setTheme(theme);
}
......
if (r.isPersistable()) {//根據本地是否持久化來判斷走那個方法，（這個持久化個人理解是activity被不正常銷燬造成的）
//這個方法調用的是activity的oncreate方法
mInstrumentation.callActivityOnCreate(activity, r.state, r.persistentState);
} else {
mInstrumentation.callActivityOnCreate(activity, r.state);
}
......
if (!r.activity.mFinished) {
activity.performStart();//調用activity的onstart方法
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) {//r.state是AMS傳過來的，也就是說OnRestoreInstanceState的調用取決於AMS是否想恢復activity。
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;
}通過上面的代碼可以看到activity再啓動的時候首選調用attach--->oncreate--->onStart--->onPostCreate
對於attach是activity的一些初始化配置，在這個方法中會創建PhoneWindow對象，對於onPostCreate方法是Activity完全起來之後調用的方法（官方解釋Called when activity start-up is complete (after onStart() and onRestoreInstanceState(Bundle) have been called），對於這個方法目前不知道有什麼特殊的用法如有特殊用法，希望能提出。其他的兩個方法這裏就不多說了我們常用的方法。上面還有個不是生命週期的一部分的是onRestoreInstanceState這個方法的調用是在AMS判定需要調用的時候纔會調用（轉屏，activity不正常被系統回收等）
final void handleResumeActivity(IBinder token,
boolean clearHide, boolean isForward, boolean reallyResume, int seq, String reason) {
......
// TODO Push resumeArgs into the activity for consideration
r = performResumeActivity(token, clearHide, reason);
.....
if (a.mVisibleFromClient && !a.mWindowAdded) {//將decor添加到Window上
a.mWindowAdded = true;
wm.addView(decor, l);
}
....
} public final ActivityClientRecord performResumeActivity(IBinder token,
boolean clearHide, String reason) {
......
try {
r.activity.onStateNotSaved();
r.activity.mFragments.noteStateNotSaved();
if (r.pendingIntents != null) {
deliverNewIntents(r, r.pendingIntents);
r.pendingIntents = null;
}
if (r.pendingResults != null) {
deliverResults(r, r.pendingResults);
r.pendingResults = null;
}
r.activity.performResume();
......
}
return r;
} final void performResume() {
performRestart();
.....
mInstrumentation.callActivityOnResume(this);//調用了onResume方法
if (!mCalled) {
throw new SuperNotCalledException(
"Activity " + mComponent.toShortString() +
" did not call through to super.onResume()");
}
......
mFragments.dispatchResume();
mFragments.execPendingActions();
onPostResume();//
if (!mCalled) {
throw new SuperNotCalledException(
"Activity " + mComponent.toShortString() +
" did not call through to super.onPostResume()");
}
} final void performRestart() {
mFragments.noteStateNotSaved();
if (mToken != null && mParent == null) {
// No need to check mStopped, the roots will check if they were actually stopped.
WindowManagerGlobal.getInstance().setStoppedState(mToken, false /* stopped */);
}
if (mStopped) {//當時從stop狀態恢復的時候走下面的代碼
mStopped = false;
synchronized (mManagedCursors) {
final int N = mManagedCursors.size();
for (int i=0; i<N; i++) {
ManagedCursor mc = mManagedCursors.get(i);
if (mc.mReleased || mc.mUpdated) {
if (!mc.mCursor.requery()) {
if (getApplicationInfo().targetSdkVersion
>= android.os.Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
throw new IllegalStateException(
"trying to requery an already closed cursor "
+ mc.mCursor);
}
}
mc.mReleased = false;
mc.mUpdated = false;
}
}
}
mCalled = false;
mInstrumentation.callActivityOnRestart(this);
if (!mCalled) {
throw new SuperNotCalledException(
"Activity " + mComponent.toShortString() +
" did not call through to super.onRestart()");
}
performStart();
}
}到這裏activity就算啓動完成了，顯現出來了，上面的代碼分析是Activity啓動的聲明週期，下一篇分析Activity關閉的生命週期