wpf 根据index操作该控件的子项(如:根据ListBox操作其包含的ListBoxItem)

<ListBox x:Name ="listBox">
            <ListBoxItem x:Name ="ListBoxItem1" Content="ListBoxItem"/>
            <ListBoxItem x:Name ="ListBoxItem2" Content="ListBoxItem"/>
            <ListBoxItem x:Name ="ListBoxItem3" Content="ListBoxItem"/>
 </ListBox><ListBox x:Name ="listBox">
            <ListBo