public static void main(String[] args) {
        // TODO Auto-generated method stub
        File file = new File("c:\\wang\\test.xlsx");
        FileInputStream in = null;
        FileOutputStream out = null;
        try {
            in = new FileInputStream(file);
            out = new FileOutputStream(new File("c:\\wang\\test1.xlsx"));
            byte zhongzhuan[] = new byte[(int) file.length()];
            int len;
            if ((len = in.read(zhongzhuan, 0, zhongzhuan.length)) != -1) {
                out.write(zhongzhuan, 0, len);
                out.flush();
            }
            out.close();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {
            if (out != null) {
                try {
                    out.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (in != null) {
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }

            }
        }
    }

------解决方案--------------------
防止NullPointException
一般
FileInputStream in=null;
try{
   ...
   in = new ...//如果这里之前出现异常，则in = null
   ...
}catch(Exception e){
   ...
}finally{
   if(in!=null){//这里防止出现异常时in为null
       in.close();
   }
}

------解决方案--------------------
那两句在那位置是有问题的，源代码写得不好。
out.close();
 if(out!=null) {
 out.close();  
 }
在没异常情况下，这样会重复关闭。  
  if(out!=null) {
 out.close();  
 }
就是多余的了。