NoSuchProvider JavaX邮件

Question

我总是会犯错误：

javax.mail.NoSuchProviderException: Invalid protocol: null
    at javax.mail.Session.getProvider(Session.java:525)
    at javax.mail.Session.getStore(Session.java:620)
    at javax.mail.Session.getStore(Session.java:600)
    at javax.mail.Session.getStore(Session.java:586)
    at de.jankrb.mailcrawler.methods.CheckAll.check(CheckAll.java:23)
    at de.jankrb.mailcrawler.Launcher.main(Launcher.java:10)

我什么也没试，因为我在网上没有发现任何东西。

这是在制造麻烦：

Properties properties = new Properties();

            properties.put("mail.transport.protocol", "smtp");
            properties.put("mail.smtp.host", HOST);
            properties.put("mail.user", USER);
            properties.put("mail.password", PASS);

            Session session = Session.getDefaultInstance(properties);

            Store store = session.getStore();
            store.connect(HOST, USER, PASS);

Launcher.java:10只使用这个方法，上面的片段就在里面。

Answer 1

Properties properties = new Properties();

        properties.put("mail.store.protocol", "pop3");
        properties.put("mail.pop3.host", HOST);
        properties.put("mail.pop3.port", "995");
        properties.put("mail.pop3.ssl.trust", "true");
        //properties.put("mail.pop3.starttls.enable", "true");

        Session session = Session.getDefaultInstance(properties);

        Store store = session.getStore("pop3s");
        store.connect(HOST, USER, PASS);

        Folder folder = store.getFolder("INBOX");
        folder.open(Folder.READ_ONLY);

这是我正在使用的代码及其工作原理。无论如何，谢谢