批量重命名一个文件夹的文件，例如：img下有600张图片，对其重名

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

public class FileUtilDeal {
		public static void main(String[] args) {
			//File file = new File("E:\\极草\\img\\F20150603-1638459781.jpg");
			//fileRename(file);
			String [] fileName = getFileName("E:\\极草\\img");  // img文件夹下所有的文件名数组
	        ArrayList listFileName = new ArrayList(); 
	        getAllFileName("E:\\极草\\img",listFileName);
	        for(String name:listFileName)
	        {
	        	fileRename(name);
	        }
		}
		
		public static void fileRename(String fileName){
			File files = new File("E:\\极草\\img\\"+fileName);
			String filePath = files.getPath();
			System.out.println(filePath);
			if(files.exists()){
				files.renameTo(new File("E:\\极草\\img\\"+add000(fileName)+fileName));
			}
		}
		
		public static void getAllFileName(String path,ArrayList fileName)
	    {
	        File file = new File(path);
	        File [] files = file.listFiles();
	        String [] names = file.list();
	        if(names != null)
	        fileName.addAll(Arrays.asList(names));
	        for(File a:files)
	        {
	            if(a.isDirectory())
	            {
	                getAllFileName(a.getAbsolutePath(),fileName);
	            }
	        }
	    }
		//
		public static String [] getFileName(String path)
	    {
	        File file = new File(path);
	        String [] fileName = file.list();
	        return fileName;
	    }
		//保证文件名的长度为30个字符
		public static String  add000(String fileName){
			String prefix=fileName.substring(fileName.lastIndexOf(".")+1);
			int dot = fileName.lastIndexOf('.'); 
            String f = fileName.substring(0, dot); 
			int _len = 30 - f.length();
			StringBuffer buf = new StringBuffer();
			for (int i = 0; i < _len; i++) {
				buf.append("0");
			}
			return buf.toString();
		}
}