如何使用sendgrid with java在不进行硬编码的情况下初始化电子邮件

dependencies {
    implementation 'com.sendgrid:sendgrid-java:4.7.0'
}

import com.sendgrid.*;

public class SendGridExample {
    public static void main(String[] args) {
        String apiKey = "YOUR_SENDGRID_API_KEY";
        SendGrid sg = new SendGrid(apiKey);
    }
}

import com.sendgrid.*;

public class SendGridExample {
    public static void main(String[] args) {
        String apiKey = "YOUR_SENDGRID_API_KEY";
        SendGrid sg = new SendGrid(apiKey);

        Email from = new Email("from@example.com");
        String subject = "Hello World";
        Email to = new Email("to@example.com");
        Content content = new Content("text/plain", "This is a test email.");

        Mail mail = new Mail(from, subject, to, content);
    }
}

import com.sendgrid.*;

public class SendGridExample {
    public static void main(String[] args) {
        String apiKey = "YOUR_SENDGRID_API_KEY";
        SendGrid sg = new SendGrid(apiKey);

        Email from = new Email("from@example.com");
        String subject = "Hello World";
        Email to = new Email("to@example.com");
        Content content = new Content("text/plain", "This is a test email.");

        Mail mail = new Mail(from, subject, to, content);

        Request request = new Request();
        try {
            request.setMethod(Method.POST);
            request.setEndpoint("mail/send");
            request.setBody(mail.build());

            Response response = sg.api(request);
            System.out.println(response.getStatusCode());
            System.out.println(response.getBody());
            System.out.println(response.getHeaders());
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }
}