android启动流程分析（二）

上一篇介绍了apk启动的流程到了创建activity的创建这里接着继续分析，先上图片

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这里从handleLaunchActivity方法继续分析，如不明白的可以参考上一篇的分析android启动流程分析，这边直接就上代码了

  private void handleLaunchActivity(ActivityClientRecord r, Intent customIntent, String reason) {        ......        Activity a = performLaunchActivity(r, customIntent);//创建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);//通过Instrumentation这个类创建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();//设置主题                   if (theme != 0) {                         activity.setTheme(theme);                     }                ......                if (r.isPersistable()) {//根据本地是否持久化来判断走那个方法，（这个持久化个人理解是activity被不正常销毁造成的）                                        //这个方法调用的是activity的oncreate方法                    mInstrumentation.callActivityOnCreate(activity, r.state, r.persistentState);                } else {                    mInstrumentation.callActivityOnCreate(activity, r.state);                }...... if (!r.activity.mFinished) {                    activity.performStart();//调用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传过来的，也就是说OnRestoreInstanceState的调用取决于AMS是否想恢复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;    }

通过上面的代码可以看到activity再启动的时候首选调用attach--->oncreate--->onStart--->onPostCreate

对于attach是activity的一些初始化配置，在这个方法中会创建PhoneWindow对象，对于onPostCreate方法是Activity完全起来之后调用的方法（官方解释Called when activity start-up is complete (after onStart() and onRestoreInstanceState(Bundle) have been called），对于这个方法目前不知道有什么特殊的用法如有特殊用法，希望能提出。其他的两个方法这里就不多说了我们常用的方法。上面还有个不是生命周期的一部分的是onRestoreInstanceState这个方法的调用是在AMS判定需要调用的时候才会调用（转屏，activity不正常被系统回收等）

    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) {//将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);//调用了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) {//当时从stop状态恢复的时候走下面的代码            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();        }    }

通过上面的方法可以找到activity接下来正常的运行声明周期应该是-onResure---->onPostResure,但是如果要是从stop状态下回复Activity的时候就会先调用onRestart--->onstart-->onResure--->onPostResure

到这里activity就算启动完成了，显现出来了，上面的代码分析是Activity启动的声明周期，下一篇分析Activity关闭的生命周期