java通过Gmail API谷歌应用程序引擎发送电子邮件

Question

正在尝试使用Gmail API将电子邮件发送到GAE。之前，我在凭证页面中创建了一个服务帐户密钥，它在setServiceAccountPrivateKeyFromP12File参数中生成一个.P12 file。它有一个ID键连接到帐户example@appspot.gserviceaccount.com到服务帐户页。守则：

    /* Application name. */
    private static final String APPLICATION_NAME = "appnamefromappengine";

    String emailAddress = "somename@appspot.gserviceaccount.com";
    JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();
    try {
        HttpTransport httpTransport = GoogleNetHttpTransport.newTrustedTransport();

        Set<String> scopes = new HashSet<String>();
        scopes.add(GmailScopes.GMAIL_SEND);
        scopes.add(GmailScopes.GMAIL_COMPOSE);
        scopes.add(GmailScopes.MAIL_GOOGLE_COM);
        scopes.add("https://www.googleapis.com/auth/admin.directory.user");

        GoogleCredential credential = new GoogleCredential.Builder()
            .setTransport(httpTransport)
            .setJsonFactory(JSON_FACTORY)
            .setServiceAccountId(emailAddress)
            .setServiceAccountPrivateKeyFromP12File(new File("/home/myuser/Test/src/main/webapp/resources/**somename**cd30e7118ad5.p12"))
            .setServiceAccountScopes(scopes)
            .setServiceAccountUser("somename@appspot.gserviceaccount.com")
            .build();
        Gmail gmail = new Gmail
            .Builder(httpTransport, JSON_FACTORY, credential)
            .setApplicationName(APPLICATION_NAME)
            .build();

        Properties props = new Properties();
        Session session = Session.getDefaultInstance(props, null);
        MimeMessage message = new MimeMessage(session);
        message.setFrom(new InternetAddress("someemail@gmail.com"));
        message.addRecipient(javax.mail.Message.RecipientType.TO, new InternetAddress("recipient@gmail.com"));
        message.setSubject("Test Mail");
        message.setText("Test Mail");

        Message msg = createMessageWithEmail(message); //createMessageWithEmail function from Gmail API
        msg = gmail.users().messages().send(emailAddress, msg).execute();

        System.out.println("Mail was sent. Message id: " + msg.getId());

    } catch (GeneralSecurityException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (MessagingException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

它会返回以下错误：

com.google.api.client.googleapis.json.GoogleJsonResponseException: 400 Bad Request { "code" : 400,
"errors" : [ { "domain" : "global", "message" : "Bad Request", "reason" : "failedPrecondition" } ],
"message" : "Bad Request" }

我不确定我在代码中或谷歌云控制台中设置的参数是错误的。我还能试什么

Answer 1

问题是我没有将服务帐户的全域授权配置为管理控制台

1. Go to your Google Apps domain’s Admin console.

2. Select Security from the list of controls. If you don't see Security listed, select More controls from the gray bar at the bottom of the page, then select Security from the list of controls. If you can't see the controls, make sure you're signed in as an administrator for the domain.

3. Select Show more and then Advanced settings from the list of options.

4. Select Manage API client access in the Authentication section.

5. In the Client Name field enter the service account's Client ID. You can find your service account's client ID in the Service accounts section of the Developers Console's Permissions page.

6. In the One or More API Scopes field enter the list of scopes that your application should be granted access to. For example, if your application needs domain-wide access to the Google Drive API and the Google Calendar API, enter: https://www.googleapis.com/auth/drive, https://www.googleapis.com/auth/calendar.

7. Click Authorize.

所有文档：
https://developers.google.com/identity/protocols/OAuth2ServiceAccount

Answer 2

您也可以选择使用这样一个库，它将为您完成所有设置： https://github.com/3wks/spring-gae-gmail