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

1 package com_2; 2  3 import java.io.File; 4 import java.io.FileInputStream; 5 import java.io.FileOutputStream; 6 import java.io.FilenameFilter; 7 import java.io.IOException; 8 import java.io.InputStream; 9 import java.io.OutputStream;10 11 public class Jad2Java {12 13     public static void main(String[] args) throws Exception {14         // TODO Auto-generated method stub15 16         File srcDir = new File("E:\\java");17         if(!(srcDir.exists() && srcDir.isDirectory())){18             throw new Exception("目录不存在");19         }20         File[] files = srcDir.listFiles(new FilenameFilter(){21 22             @Override23             public boolean accept(File dir, String name) {24                 25                 return name.endsWith(".java");26             }27             28         });29         System.out.println(files.length);30         File destDir = new File("E:\\jad");31         if(!destDir.exists()){32             destDir.mkdir();33         }34         for(File f : files){35             FileInputStream fis = new FileInputStream(f);36             String destFileName = f.getName().replaceAll("\\.java$", ".jad");37             FileOutputStream fos = new FileOutputStream(new File(destDir,destFileName));38             copy(fis,fos);39             fis.close();40             fos.close();41         }42 43     }44 45     private static void copy(InputStream ips, OutputStream ops) throws IOException {46         47         int len = 0;48         byte[] buf = new byte[1024];49         while((len = ips.read(buf)) != -1){50             ops.write(buf,0,len);51         }52         53     }54     55 }