這是一個簡單的往文件里寫內容的方法：

  public void writeFile(String fileName, String content) throws Exception {
    File f = new File(fileName);
    if (f.exists()) {
      f.delete();
    }
    f.createNewFile();
    FileWriter fileWriter = new FileWriter(f);
    PrintWriter writer = new PrintWriter(fileWriter);
    writer.write(content);
    writer.flush();
    writer.close();
  }