创建文件和目录

        File file = new File("demo.txt");
        if(!file.exists()){
            file.createNewFile();
        }
        File dirs = new File(
                "a" + File.separator +
                "b" + File.separator +
                "c" + File.separator +
                "d" + File.separator +
                "e" + File.separator +
                "f" + File.separator +
                "g" + File.separator +
                "h" + File.separator +
                "i");
        if(!dirs.exists()){
            dirs.mkdirs();
        }