/*** 文件后缀名修改器* 说明：UI部分* @author Yours风之恋* * 创建时间：2012-8-8**/
public class UserInterface {public static void mainMenuDisplay() {System.out.println("-------------------批量修改文件后缀名----------------------");System.out.println("  Copyright 2012              ");System.out.println("  @author Yours风之恋                     ");System.out.println("-----------------------------------------------------------\n");}public static void helpMenuDisplay() {System.out.println("-------------------系统帮助-------------------");System.out.println("本系统需要两个参数：");System.out.println("1,需要修改的文件所在文件夹目录");System.out.println("2,自定义的后缀名");}public static void waitUserInput() {System.out.println();System.out.println("系统正在等待您的输入：");}
}

import java.io.File;
import java.util.Scanner;public class FEA {public static void main(String[] args) {init();start();}public static void start() {System.out.println("请输入文件所在文件夹目录,按回车键结束。");String dir = getInput();list(dir, 0);System.out.println("请输入自定义的后缀名,按回车键结束。");String extension = getInput();long l1 = System.currentTimeMillis();change(dir, extension);long l2 = System.currentTimeMillis();System.out.println("后缀名修改成功,用时：" + (l2-l1) + "毫秒");}public static void listFiles(File f, int level, int key) {if (!f.isDirectory()) {System.out.println("目录不正确，本次服务结束 ！");System.exit(0);}String preStr = "";for (int i = 0; i < level; i++) {preStr += "    ";}File[] childs = f.listFiles();for (int i = 0; i < childs.length; i++) {System.out.println(preStr + childs[i].getName());if (childs[i].isDirectory() && key == 0) {listFiles(childs[i], level + 1, key);}}}public static void changeExtension(File f, String extension) {if (!f.isDirectory()) {System.out.println("目录不正确，本次服务结束 ！");System.exit(0);}File[] childs = f.listFiles();for (int i = 0; i < childs.length; i++) {if (childs[i].isFile()) {String parStr = childs[i].getParent();String filStr = childs[i].getName();StringBuilder sbStr = new StringBuilder(filStr);for(int k = sbStr.length() -1; k >= 0 ; k--) {char c = sbStr.charAt(k);if(c != '.') {sbStr.deleteCharAt(k);} else {break;}}sbStr.append(extension);File fx = new File(parStr, sbStr.toString());childs[i].renameTo(fx);}if (childs[i].isDirectory()) {changeExtension(childs[i], extension);}}}public static void change(String dir, String extension) {File f = new File(dir);changeExtension(f, extension);}public static void list(String dir, int key) {File f = new File(dir);listFiles(f, 0, key);}public static String getInput() {Scanner sc = new Scanner(System.in);return sc.next();}public static void init() {UserInterface.mainMenuDisplay();UserInterface.helpMenuDisplay();UserInterface.waitUserInput();}
}

另有源码和可执行文件:http://download.csdn.net/detail/haifengzhilian/4494395