public String findDrafts(String userId) {
   List<EmailDraft> drafts = emailDraftDao.findEmailDrafts(userId);
   String jsonString = "{'drafts':[";
   for (int i = 0; i < drafts.size(); i++) {
     EmailDraft draft = drafts.get(i);
     String settingString = "{";
     settingString += "'sender':'" + draft.getSentEmail() + "',";
     SimpleDateFormat format = new SimpleDateFormat("yy年MM月dd日 HH:mm:ss");
     String date = format.format(draft.getTime());
     settingString += "'time':'" + date + "',";
     settingString += "'content':'" + draft.getContent() + "',";
     settingString += "'theme':'" + draft.getTitle() + "'";
     settingString += "},";
     jsonString += settingString;
   }
   jsonString = jsonString.substring(0, jsonString.length() - 1);
   jsonString += "]}";
   System.out.println(jsonString);
   return jsonString;
 }
 public String saveEmailDraft(String subject, String receiver, String content, String userId) {
   EmailDraft draft = new EmailDraft();
   draft.setContent(content);
   draft.setSentEmail(receiver);
   draft.setTitle(subject);
   draft.setTime(new Date());
   User user = new User();
   user.setId(userId);
   draft.setUser(user);
   boolean flag = emailDraftDao.saveEmailDraft(draft);
   if (flag) {
     return "{success:true}";
   } else {
     return "{success:false}";
   }
 }