网易邮件采集器（5）

去重：获取最新的邮件mid并保存，以后每采集一次得到邮件mid与存储的mid比较，若不相等则为新邮件，采集并保存，若相等，则当前邮件及之后的邮件均为已经采集的邮件，当前采集可直接结束！

   (1)获取最新mid

int i = 0;

        Elements links = d.select("[name=\"id\"]");

        for (Element link : links) {
            MailGet mg = new MailGet(link.text());

            ls.add(mg);
            if (i == 0) {
                mid = mg.getId();
            }

（2）读取文件中存储的mid信息，比较mid，并在控制台输出新邮件

for (MailGet mg : ls) {
            // 存
            try {
                File fa = new File(Constants.midPath, Constants.midFileName);
                if (!fa.exists()) {
                    fa.createNewFile();
                }
                FileReader fr = new FileReader(fa);
                char[] a = new char[1024];
                String str = "";
                int j = 0;
                while ((j = fr.read(a)) > 0) {
                    str += new String(a, 0, j);
                }
                // System.out.println(str + mg.getId());

                fr.close();
                if (str.equals(mg.getId())) {
                    break;
                } else {

                    System.out.println(mg);
                    mailDetail(mg);
                    File fi = new File(Constants.youjianPath,
                            mg.getReceivedDate().replace(":", "").replace("-", "") + ".json");

                    if (!fi.exists()) {
                        fi.createNewFile();
                    }

                    FileWriter fw = new FileWriter(fi);
                    fw.write(JSON.toJSONString(mg));

                    fw.close();
                    i++;

                }
            } catch (Exception e) {
                e.printStackTrace();
            }

        }

（3）重新存一次mid的信息

        try {
            File fl = new File(Constants.midPath, Constants.midFileName);

            FileWriter fwm = new FileWriter(fl);

            fwm.write(mid);

            fwm.close();
        } catch (Exception e) {
            e.printStackTrace();
        }