改文件扩展名2

今天要给一大堆文件换扩展名.网上找了半天没找到合适的工具.就用java写了一个.写的太丑陋了.都不想再看.以后有时间了好好另写个.

//改目录下文件名的扩展名
import java.io.File;
public class re {
    public static void main(String[] args){
        File file = new File("D:\\tmep");
        String pre = new String("sql");
        String aft = new String("txt");
        run(file,pre,aft);
    }
    public static void run(File f,String from,String to) {
        
        if (f.isFile())    renname(f,from,to);
        else for (File a:f.listFiles())    run(a,from,to);
        
    }
    public static String getSubname(File f) {
        String[] names = f.getName().split("\\.");
        if (names.length>1)        return names[names.length-1];
        else return "";
    }
    public static String getname(File f ) {
        String[] names = f.getName().split("\\.");
        String filename = names[0];
        for(int i=1;i<names.length-1;i++  ) {
            filename = filename "." names[i];
        }
        return filename;
    }
    public static void renname(File renf,String from,String to) {
            if (renf.isFile()&&(getSubname(renf).equalsIgnoreCase(from))) {
            renf.renameTo(new File(getname(renf)+ "."+ to));
            System.out.println(renf.getPath()+ "->"+ getname(renf)+ "."+ to);
        }
    }

}