try{
            String fileName = "out.txt";//指定文件名
            File file = new File(fileName);
            FileOutputStream out = new FileOutputStream(file);//建立输出流
            byte[] b = new byte[1024];
            String str = "Nice to see you again!";
            b = str.getBytes();//String转化为byte[]
            out.write(b);//写入文本内容
        }
        catch(IOException e){
            System.out.println(e.toString());
        }