有时候我们需要在不同的时候改变ActionBar中MenuItem的项数，或者隐藏某些MenuItem，百度上找了很久没什好资料，还是Google了一下，StackOverFlow上有大神解决了。

先看看  StackOverFlow 上的问题：

@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		getMenuInflater().inflate(R.menu.action_main, menu);
		MenuItem actionSettings = menu.findItem(R.id.action_settings);
		if(...满足某一条件...){
			actionSettings.setVisible(true);
	        else{
			actionSettings.setVisible(false);
		}
		return true;
	}

前言
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声明
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正文

	private boolean mHasInit = false;
	private boolean mHasKeyboard = false;
	private int mHeight;
    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
    	// TODO Auto-generated method stub
    	super.onLayout(changed, l, t, r, b);
    	if(!mHasInit) {
			mHasInit = true;
			mHeight = b;   
			System.out.println("mHeight= "+b);
		} else {
			mHeight = mHeight < b ? b : mHeight;
		}
		
		if(mHasInit && mHeight > b) {                  //mHeight代表键盘的真实高度 ,b代表在窗口中的高度 mHeight>b 
			mHasKeyboard = true;
            Xlog.e(TAG, "bottomBar---------------->出来了");
		}
		if(mHasInit && mHasKeyboard && mHeight == b) {  // mHeight = b 
			mHasKeyboard = false;
			cancelBottomBarAnimation();
            this.setVisibility(View.VISIBLE);
            mShowing = false;
            Xlog.e(TAG, "bottomBar---------------->隐藏了");
		}
    }

public class CustomViewGroup extends ViewGroup{

	public CustomViewGroup(Context context) {
		super(context);
		// TODO Auto-generated constructor stub
	}
	
	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		// TODO Auto-generated method stub

	    final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        final int widthSize = MeasureSpec.getSize(widthMeasureSpec);
        final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        final int heightSize = MeasureSpec.getSize(heightMeasureSpec);
        /**
         * 依据specMode的值，如果是AT_MOST，specSize 代表的是最大可获得的空间；如果是EXACTLY，specSize 代表的是精确的尺寸；如果是UNSPECIFIED，对于控件尺寸来说，没有任何参考意义。 
         */
        if (widthMode != MeasureSpec.EXACTLY || heightMode != MeasureSpec.EXACTLY)
        {
            throw new IllegalStateException("ApplicationsStackLayout can only be used with "
                    + "measure spec mode=EXACTLY");
        }
	    measureChildren(widthMeasureSpec, heightMeasureSpec);     

	    setMeasuredDimension(widthSize, heightSize);  
	}

	@Override
	protected void onLayout(boolean changed, int l, int t, int r, int b) {
		// TODO Auto-generated method stub
		int mTotalHeight = 0;  

	       // 遍历所有子视图     
	    int childCount = getChildCount();  
	    for (int i = 0; i < childCount; i++) {  
	        View childView = getChildAt(i);  
	        
	        // 获取在onMeasure中计算的视图尺寸  
	        int measureHeight = childView.getMeasuredHeight();  
	        int measuredWidth = childView.getMeasuredWidth();  
	        if(i==1){
	        	childView.layout(50, mTotalHeight, measuredWidth+50, mTotalHeight + measureHeight);
	        }else
	        childView.layout(l, mTotalHeight, measuredWidth, mTotalHeight + measureHeight);  

	        mTotalHeight += measureHeight;  


	    }  
	}

	
}

使用自定义的ViewGroup

<CustomViewGroup
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="#ffffff">
        <TextView android:layout_width="wrap_content"
            android:layout_height="50dp"
            android:text="fasdjflsadjlf"
            android:background="#555555"/>
        <TextView android:layout_width="wrap_content"
            android:layout_height="50dp"
            android:text="fasdjflsadjlf"
            android:background="#999999"/>
    </CustomViewGroup>