Introduction

email-util is simple, declarative utility library. Key features are:

• declarative email building;
• text or html rendering;
• annotation support for binding object value to template;
• built-in smtp support for simple or multipart messages;
• support for sending mails from other channels;

Download

For downloading dependency:

dependencies {
    implementation 'com.nicat.asgarzada:email-util:1.0.0'
}

Repository setting:

repositories {
    maven {
        url = uri("https://maven.pkg.github.com/nasgarzada/mail-util")
        credentials {
            username = project.findProperty("gpr.user") ?: "<your username>"
            password = project.findProperty("gpr.key") ?: "<your personal access token>"
        }
    }
}

In "<your username>" part add github your username. "<your personal access token>" part generate personal access token for read packages.

Examples

Multipart mail sender

Following example shows multipart message building and sending:

public class Main {
    public static void main(String[] args) throws FileNotFoundException {
        Email.builder()
                .from("[email protected]")
                .to("[email protected]", false)
                .subject("Just testing my new library")
                .withRenderer()
                .path("template.txt")
                .bindingObject(new Example("Nijat Asgarzada"))
                .build()
                .withAttachment()
                .file("image.png")
                .build()
                .send(new MultipartMessageSender("email.properties"));
    }

    public static class Example {
        @Bind(key = "user")
        private String fullName;

        public Example(String fullName) {
            this.fullName = fullName;
        }

        public String getFullName() {
            return fullName;
        }

        public void setFullName(String fullName) {
            this.fullName = fullName;
        }

        @Override
        public String toString() {
            return "Example{" +
                    "fullName='" + fullName + '\'' +
                    '}';
        }
    }
}

In the example, you can see that, we have used built in MultipartMessageSender object for sending message. We passed properties file to object. Properties file is like that:

mail.smtp.auth=true
mail.smtp.starttls.enable=true

mail.smtp.host=smtp.gmail.com
mail.smtp.port=587
mail.username[email protected] 
mail.password= <your app password>
mail.transport.protocol=smtp

mail.content.type=text/html  #if you don't set default is text/plain
mail.default.charset=UTF-8  #if you don't set it's default value

Another factor is @Bind(key = "user") annotation. This annotation enables replacing user field in template with value of fullName field of Example object.

Custom mail sender

Another key feature of util is customization of sender method. If you don't need sending via smtp, then you can implement your own logic. In the following example, I've implemented sending mail entity to queue:

public class QueueSender<Void> implements Sender<Void> {
    private final AmqpTemplate amqpTemplate;
    private final String queueName;
    private final ObjectMapper objectMapper;
    
    public QueueSender(AmqpTemplate amqpTemplate, String queueName, ObjectMapper objectMapper) {
        this.amqpTemplate = amqpTemplate;
        this.queueName = queueName;
        this.objectMapper = objectMapper;
    }

    @Override
    public Void send(MailEntity mailEntity) {
        this.amqpTemplate.convertAndSend(queueName, objectMapper.writeValueAsString(mailEntity));
        return null;
    }
}