列出文件夹中分级目录java

package test;

import java.io.File;

public class exportFileName {
    public static void main(String[] args) {
        export("D:/test/");
    }

    private static void export(String filePath){
        if(filePath==null){
            System.out.println("传入路径为空。");
            return;
        }
        if(filePath.endsWith("\\")){
            filePath = filePath.replaceAll("\\", "/");
        }

        File path = new File(filePath);
        if(!path.exists()){
            System.out.println(filePath+"路径不存在。");
            return;
        }

        File[] files = path.listFiles();
        if(files!=null&&files.length>0){
            for(File file : files){
                getNames(file,file.getPath());
                System.out.println("");
            }
        }
    }

    private static String getNames(File file, String parentName){
        if(file==null){
            return null;
        }

        if(file.isDirectory()){
            String pathName = file.getName();
            if(!parentName.contains(pathName)){
                String p = file.getParentFile().getName();
                String pTab = parentName.replaceAll(p, "");
                pTab = pTab.replaceAll("\\|-", "");

                String tab = "\t";
                pathName = pTab + tab +"|-"+pathName;
            }

            System.out.println(pathName);

            File[] files = file.listFiles();
            if(files==null||files.length==0){
                return null;
            }
            for(File f: files){
                getNames(f,pathName);
            }
        }else if(file.isFile()){
            String fileName = file.getName();
            if(!parentName.contains(fileName)){
                String p = file.getParentFile().getName();
                String pTab = parentName.replaceAll(p, "");
                pTab = pTab.replaceAll("\\|-", "");

                String tab = "\t";
                fileName = pTab + tab + "|-" + fileName;
            }

            System.out.println(fileName);
            return fileName;
        }
        return null;
    }
}