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

public class Test3 {
//判断文件名后缀是.java吗？是的话true,不是的话false
private static FileFilter fileFilter = new FileFilter() {

@Override
public boolean accept(File arg0) {
// TODO Auto-generated method stub
String tmp = arg0.getName().toLowerCase();
if(tmp.endsWith(".java")){
return true;
}
return false;
}
};

public static void main(String[] args) throws Exception {
// TODO Auto-generated method stub
File file = new File("D:/java");
File[] files = file.listFiles(fileFilter);
InputStream in = null;
OutputStream out = null;
String fileName = null;
String destName = null;
File f = new File("D:/jad");
for (File file2 : files) {
in = new FileInputStream(file2);
if(!f.exists()){
f.mkdir();
}
fileName = file2.getName();
destName = (String) fileName.subSequence(0, fileName.lastIndexOf("."));
out = new FileOutputStream(new File("D:/jad/"+destName+".jad"));
int len = 0;
byte[] b = new byte[1024];
while((len = in.read(b))!= -1){
out.write(b, 0, len);
//System.out.println(new String(b,0,len));
}
}
}

}