面试题2

package com.maoge;

import java.io.*;

public class  {
    public static void main(String args[]) throws Exception {
        File nativeDir = new File("D:\IDEA\workspace\file");

        if (!(nativeDir.exists() && nativeDir.isDirectory())) {
            throw new Exception("目录不存在");
        }

        File[] files = nativeDir.listFiles(
                new FilenameFilter() {
                    public boolean accept(File file, String fileName) {
                        return fileName.endsWith(".java");
                    }
                }
        );

        System.out.println("文件数量：" + files.length);

        File distDir = new File("D:\IDEA\workspace\file\jad");
        if (!(distDir.exists() || distDir.isDirectory())) {
            distDir.mkdir();
        }

        for (File file : files) {
            String distFileName = file.getName().replaceAll("\.java$", ".jad");
            FileInputStream fis = new FileInputStream(file);
            File f = new File(distDir, distFileName);
            FileOutputStream fos = new FileOutputStream(f);
            copy(fis, fos);
        }

    }

    public static void copy(FileInputStream fis, FileOutputStream fos) throws IOException {
        int len = 0;
        byte[] buf = new byte[1024];
        while ((len = fis.read(buf)) != -1) {
            fos.write(buf, 0, len);
        }
    }
}