java nio:Files.isSameFile判断两个路径(Path)是否相等

    /**
     * 判断sub是否与parent相等或在其之下<br>
     * parent必须存在，且必须是directory,否则抛出{@link IllegalArgumentException}
     * @param parent 
     * @param sub
     * @return
     * @throws IOException 
     */
    public static boolean sameOrSub(Path parent,Path sub) throws IOException{
        if(null==parent)
            throw new NullPointerException("parent is null");
        if(!Files.exists(parent)||!Files.isDirectory(parent))
            throw new IllegalArgumentException(String.format("the parent not exist or not directory %s",parent));
        while(null!=sub) {
            if(Files.exists(sub)&&Files.isSameFile(parent, sub))
                return true;
            sub=sub.getParent();
        }
        return false;   
    }
    /**
     * 判断sub是否在parent之下的文件或子文件夹<br>
     * parent必须存在，且必须是directory,否则抛出{@link IllegalArgumentException}
     * @param parent
     * @param sub
     * @return
     * @throws IOException
     * @see {@link #sameOrSub(Path, Path)}
     */
    public static boolean isSub(Path parent,Path sub) throws IOException{
        return (null==sub)?false:sameOrSub(parent,sub.getParent());
    }