学步园

1：遍历文件夹

import java.io.File;
import java.util.ArrayList;

public class RunMain {
    @SuppressWarnings("unchecked")
    private static ArrayList filelist = new ArrayList();

    public static void main(String[] args) {

        long a = System.currentTimeMillis();
        refreshFileList("D:\\web");
        System.out.println(System.currentTimeMillis() - a);
    }

    @SuppressWarnings("unchecked")
    public static void refreshFileList(String strPath) {
        File dir = new File(strPath);
        File[] files = dir.listFiles();

        if (files == null)
            return;
        for (int i = 0; i < files.length; i++) {
            if (files[i].isDirectory()) {
                refreshFileList(files[i].getAbsolutePath());
            } else {
                String strFileName = files[i].getAbsolutePath().toLowerCase();
                System.out.println("---" + strFileName);
                filelist.add(files[i].getAbsolutePath());
            }
        }
    }
} 

2：清空文件夹，并保留根路径

public void deleteFolder(String dir) {
  File delfolder=new File(dir); 
  File oldFile[] = delfolder.listFiles();
  try 
  { 
     for (int i = 0; i < oldFile.length; i++)
     {
        if(oldFile[i].isDirectory())
        {
           deleteFolder(dir+oldFile[i].getName()+"//"); //递归清空子文件夹
        }
        oldFile[i].delete();
     }
  } 
  catch (Exception e) 
  { 
    System.out.println("清空文件夹操作出错!"); 
    e.printStackTrace(); 
  }
}