编写一个程序,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 { private static FileFilter fileFilter = new FileFilter() { @Override public boolean accept(File arg0) { // TODO Auto-generated method stub String tmp = arg0.getName().toLowerCase(); return true; } return false; } }; public static void main(String[] args) throws Exception { // TODO Auto-generated method stub File file = new File("D:/java"); 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()){ } fileName = file2.getName(); destName = (String) fileName.subSequence(0, fileName.lastIndexOf(".")); int len = 0; byte[] b = new byte[1024]; while((len = in.read(b))!= -1){ out.write(b, 0, len); } } } }