ViewStub的使用及原理

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    ..............
    
    <ViewStub 
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/lay_guide"
        android:layout="@layout/guide_main_tab"/>
    
</RelativeLayout>

if(!GuidePreference.isGuide(getApplicationContext(), GuidePreference.MAIN_TAB_V4)){
　　ViewStub stub = (ViewStub) findViewById(R.id.lay_guide);
　　if(stub==null){
　　　　return ;
　　}
　　mFilpper = (ViewFlipper) stub.inflate() ;
　　mFilpper.setOnClickListener(new View.OnClickListener() {
                
　　　　@Override
　　　　public void onClick(View v) {
　　　　　　guideSwitch() ;
　　　　}
　　});
}

public View inflate() {
        final ViewParent viewParent = getParent();

        if (viewParent != null && viewParent instanceof ViewGroup) {
            if (mLayoutResource != 0) {
                final ViewGroup parent = (ViewGroup) viewParent;
                final LayoutInflater factory;
                if (mInflater != null) {
                    factory = mInflater;
                } else {
                    factory = LayoutInflater.from(mContext);
                }
                final View view = factory.inflate(mLayoutResource, parent,
                        false);

                if (mInflatedId != NO_ID) {
                    view.setId(mInflatedId);
                }

                final int index = parent.indexOfChild(this);
                parent.removeViewInLayout(this);

                final ViewGroup.LayoutParams layoutParams = getLayoutParams();
                if (layoutParams != null) {
                    parent.addView(view, index, layoutParams);
                } else {
                    parent.addView(view, index);
                }

                mInflatedViewRef = new WeakReference<View>(view);

                if (mInflateListener != null) {
                    mInflateListener.onInflate(this, view);
                }

                return view;
            } else {
                throw new IllegalArgumentException("ViewStub must have a valid layoutResource");
            }
        } else {
            throw new IllegalStateException("ViewStub must have a non-null ViewGroup viewParent");
        }
    }