java打印树形目录结构

import java.io.File;
public class MainTest {
public static void main(String[] args) {
String dirname = "D:\menu";
menu(dirname, 0);
}
public static void menu(String dirname, int padding){
File file = new File(dirname);
if(file.isDirectory()){
System.out.println(padding_n(padding)+"目录: " + dirname);
String s[] = file.list();
for (int i=0; i<s.length; i++){
File f = new File(dirname + "/" + s[i]);
if(f.isDirectory()){
menu(dirname+"\"+s[i], padding+4);
}else{
System.out.println(padding_n(padding+4)+"文件："+s[i]);
}
}
}
}
public static String padding_n(int n){
StringBuffer space = new StringBuffer("");
for (int i=0; i<n; i++){
space.append(" ");
}
return space.toString();
}
}