FileFilter文件过滤器

引入：将E:\java目录下的所有.java文件复制到E:\jad目录下，并将原来的文件的扩展名从.java改为.jad

 package com_2;

 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.FilenameFilter;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;

 public class Jad2Java {

     public static void main(String[] args) throws Exception {
         // TODO Auto-generated method stub

         File srcDir = new File("E:\\java");
         if(!(srcDir.exists() && srcDir.isDirectory())){
             throw new Exception("目录不存在");
         }
         File[] files = srcDir.listFiles(new FilenameFilter(){

             @Override
             public boolean accept(File dir, String name) {

                 return name.endsWith(".java");
             }

         });
         System.out.println(files.length);
         File destDir = new File("E:\\jad");
         if(!destDir.exists()){
             destDir.mkdir();
         }
         for(File f : files){
             FileInputStream fis = new FileInputStream(f);
             String destFileName = f.getName().replaceAll("\\.java$", ".jad");
             FileOutputStream fos = new FileOutputStream(new File(destDir,destFileName));
             copy(fis,fos);
             fis.close();
             fos.close();
         }

     }

     private static void copy(InputStream ips, OutputStream ops) throws IOException {

         int len = 0;
         byte[] buf = new byte[1024];
         while((len = ips.read(buf)) != -1){
             ops.write(buf,0,len);
         }

     }

 }