如何配置Java应用程序以使用OAUTH2通过Gmail服务发送电子邮件？

Question

我已经使用OAUTH2配置了Java应用程序，但是它给了我错误。有人可以给我建议解决方案吗？'

下面是代码：

public static void main (String args[]){

    String TOKEN_URL = "https://www.googleapis.com/oauth2/v4/token";
    String oauthClientId = "558561226799-6nvqdl1kabh863g1a1184t3t7fcvu82e.apps.googleusercontent.com";
    String oauthSecret = "UAPodrF7mIAverk_-A8wlWyL";
    String refreshToken = "1//0gyh0jPCTq5GSCgYIARAAGBASNwF-L9IrGNizcIn4l4tGhlORji0X6zqFsV4rsB-niM1lNtJa9nVedsTWWPBt9Uuj8pOPcHNrpfc";
    String accessToken = "ya29.a0Ae4lvC2p0j2MK6Wv5CcXvcB9VwJmukivtY7M6y6ZBntBdIls5XAXe4TCjt9zr5VuWolB0CdRJjL6UBIz5mqj63KvNxjAYU0DeNsZGbWrz7daP624ruvM-DYsvHSUx1jrUcudiUDF2YhQc3lHH8WXrAhanWIBakI170w";
    long tokenExpires = 1458168133864L;
    String username="[email protected]";

    if (System.currentTimeMillis() > tokenExpires) {
        try {
            String request = "client_id=" + URLEncoder.encode(oauthClientId, "UTF-8")
                    + "&client_secret=" + URLEncoder.encode(oauthSecret, "UTF-8")
                    + "&refresh_token=" + URLEncoder.encode(refreshToken, "UTF-8")
                    + "&grant_type=refresh_token";
            HttpURLConnection conn = (HttpURLConnection) new URL(TOKEN_URL).openConnection();
            conn.setDoOutput(true);
            conn.setRequestMethod("POST");
            PrintWriter out = new PrintWriter(conn.getOutputStream());
            out.print(request); // note: println causes error
            out.flush();
            out.close();
            conn.connect();
            try {
                HashMap<String, Object> result;
                result = new ObjectMapper().readValue(conn.getInputStream(), new TypeReference<HashMap<String, Object>>() {
                });
                accessToken = (String) result.get("access_token");
                tokenExpires = System.currentTimeMillis() + (((Number) result.get("expires_in")).intValue() * 1000);
            } catch (IOException e) {
                String line;
                BufferedReader in = new BufferedReader(new InputStreamReader(conn.getErrorStream()));
                while ((line = in.readLine()) != null) {
                    System.out.println(line);
                }
                System.out.flush();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    String mailUsername = "[email protected]";

    Properties props = new Properties();
    props.put("mail.smtp.ssl.enable", "true"); // required for Gmail
    props.put("mail.smtp.auth.mechanisms", "XOAUTH2");

    try {
        Session session = Session.getInstance(props);

        Message msg = new MimeMessage(session);
        msg.setFrom(new InternetAddress(mailUsername));
        msg.addRecipient(Message.RecipientType.TO, new InternetAddress(mailUsername));

        msg.setSubject("JavaMail OAuth2 test");
        msg.setSentDate(new Date());
        msg.setText("Hello, world with OAuth2!\n");
        msg.saveChanges();

        Transport transport = session.getTransport("smtp");
        transport.connect("smtp.gmail.com", username, accessToken);
        transport.send(msg, msg.getAllRecipients());
    } catch (AddressException e) {
        e.printStackTrace();
    } catch (NoSuchProviderException e) {
        e.printStackTrace();
    } catch (MessagingException e) {
        e.printStackTrace();
    }
}

下面是我得到的错误，我没有提到主机为localhost或任何端口号，connect方法不起作用吗？ ：

javax.mail.MessagingException: Could not connect to SMTP host: localhost, port: 25;
  nested exception is:
    java.net.ConnectException: Connection refused (Connection refused)
    at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1282)
    at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:370)
    at javax.mail.Service.connect(Service.java:275)
    at javax.mail.Service.connect(Service.java:156)
    at javax.mail.Service.connect(Service.java:105)
    at javax.mail.Transport.send0(Transport.java:168)
    at javax.mail.Transport.send(Transport.java:120)
    at com.rapidbox.wmscore.service.impl.VendorServiceImpl.main(VendorServiceImpl.java:158)
Caused by: java.net.ConnectException: Connection refused (Connection refused)
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:607)
    at java.net.Socket.connect(Socket.java:556)
    at com.sun.mail.util.SocketFetcher.createSocket(SocketFetcher.java:232)
    at com.sun.mail.util.SocketFetcher.getSocket(SocketFetcher.java:189)
    at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1250)
    ... 7 more

Process finished with exit code 0

[请有人告诉我我做错了。另外，如果有蚂蚁替代解决方案，那么将不胜感激。

Answer 1

好像您有防火墙或防病毒软件阻止了您的连接。参见JavaMail connection debugging tips。