Integrate SendGrid With a Spring Boot and Java App

In this post, you will learn how to integrate your Spring Boot and Java app with the SendGrid Web API. The following are some of the points covered:

• Create and Configure/Load the SendGrid API Key.
• Configure the SendGrid Maven entry in POM.xml.
• Use the SendGrid EmailService custom implementation.
• Invoke/Test the Email Service.

Create and Configure/Load the SendGrid API Key

• Create an account with SendGrid.com
• Go to the SendGrid Setup Guide to using the Web API page. Create an API key.
• Execute the following script in your development environment.

  echo "export SENDGRID_API_KEY='Paste_Your_API_Key'" > sendgrid.env
  echo "sendgrid.env" >> .gitignore
  source ./sendgrid.env

• Alternatively, you could also configure the SendGrid API key in your application.properties file and read the key details as part of loading the configuration beans. The following is the sample code:

  import org.springframework.beans.factory.annotation.Value;
  import org.springframework.context.annotation.Bean;
  import org.springframework.context.annotation.Configuration;
  import org.springframework.context.annotation.PropertySource;
  
  import com.sendgrid.SendGrid;
  
  @Configuration
  @PropertySource("classpath:application.properties")
  public class SendGridConfig {
  
      @Value("${sendgrid.api.key}") String sendGridAPIKey;
          return new SendGrid(sendGridAPIKey);
      }
  }

  In the above code sample, the SendGrid API Key is read from the application.properties file. The following is the content of the application.properties file.

  sendgrid.api.key = ABCcvbdTYDRS_ksjdhIUYICS.-836jksjsdhYTkPt12hdgsT-whdk
  ahdjfpT3shdBCVNS

  Make sure that you put the API key and not the API Key Id. Or, else, you would get an exception notifying you that the SendGrid API Key not working, such as,"The provided authorization grant is invalid, expired or revoked."

Configure the SendGrid Maven Entry in POM.xml

Get the latest SendGrid Java dependency from the Maven SendGrid Java page.

<!-- https://mvnrepository.com/artifact/com.sendgrid/sendgrid-java -->
<dependency>
    <groupId>com.sendgrid</groupId>
    <artifactId>sendgrid-java</artifactId>
    <version>4.1.2</version>
</dependency>

SendGrid EmailService Custom Implementation

The following represents the implementation for SendGrid APIs. Pay attention to some of the following:

• SendGrid instances are auto-wired at the time of construction.
• Content type "text/plain" is used for sending emails in plain text format.
• Content type "text/html" is used for sending emails in HTML format.

@Service
public class SendGridEmailService implements EmailService {

    private SendGrid sendGridClient;

    @Autowired
    public SendGridEmailService(SendGrid sendGridClient) {
        this.sendGridClient = sendGridClient;

    }

    @Override
    public void sendText(String from, String to, String subject, String body) {
        Response response = sendEmail(from, to, subject, new Content("text/plain", body));
        System.out.println("Status Code: " + response.getStatusCode() + ", Body: " + response.getBody() + ", Headers: "
                + response.getHeaders());
    }

    @Override
    public void sendHTML(String from, String to, String subject, String body) {
        Response response = sendEmail(from, to, subject, new Content("text/html", body));
        System.out.println("Status Code: " + response.getStatusCode() + ", Body: " + response.getBody() + ", Headers: "
                + response.getHeaders());
    }

    private Response sendEmail(String from, String to, String subject, Content content) {
        Mail mail = new Mail(new Email(from), subject, new Email(to), content);
        mail.setReplyTo(new Email("abc@gmail.com"));
        Request request = new Request();
        Response response = null;
        try {
            request.setMethod(Method.POST);
            request.setEndpoint("mail/send");
            request.setBody(mail.build());
            this.sendGridClient.api(request);
        } catch (IOException ex) {
            System.out.println(ex.getMessage());
        }
        return response;
    }
}

The above class implements the following custom Email Service interface:

public interface EmailService {
    void sendText(String from, String to, String subject, String body);
    void sendHTML(String from, String to, String subject, String body);
}

Invoke/Test the SendGrid Email Service

The following is the sample Spring Boot code which can be used to invoke the custom SendGrid email implementation created in the above example.

@SpringBootApplication
public class RecruiterbotApplication implements CommandLineRunner {

    @Autowired EmailService sendGridEmailService;

    public static void main(String[] args) {
        SpringApplication app = new SpringApplication(RecruiterbotApplication.class);
        app.run(args);
    }

    @Override
    public void run(String... arg0) throws IOException, URISyntaxException {
        this.sendGridEmailService.sendHTML("abc@gmail.com", "efg@gmail.com", "Hello World", "Hello, <strong>how are you doing?</strong>");
    }
}

Further Reading / References

• SendGrid Documentation
• SendGrid Java API Library on GitHub

Summary

In this post, you learned how to integrate SendGrid's Java Web APIs into your Spring Boot application.

Did you find this article useful? Do you have any questions or suggestions about this article? Leave a comment and ask your questions and I shall do my best to address your queries.