messenger4j: A Java library for the Messenger Platform

If you are excited about building Chatbots on the Facebook Messenger Platform, messenger4j is all you need ✌

It's fast, lightweight, feature-rich, and easy to use.

For more information on the Facebook Messenger Platform refer to the official documentation.

Features

• Full supported Receive API
  • Webhook verification
  • Signature verification
  • Automatic message / event type detection
  • Handler-based processing of messages / events
  • Fallback-mechanisms
• Full supported Send API
  • Text, Attachments, Buttons, Templates, Quick Replies - everything you need
  • Notification type support
  • Webview support
  • Fluent builder APIs
  • Pluggable HTTP-Client (okHttp is the default)
• Thread Settings support
  • Get Started Button
  • Greeting Text
  • Persistent Menu
• User Profile API support
• Messenger Extensions support
• JDK 7+ compatible
• JDK 8 lambda support
• 3 dependencies:
  • slf4j-api
  • gson
  • okHttp (optional)
• 150 kB JAR

Binaries

To add a dependency on messenger4j using Maven, use the following:

<dependency>
  <groupId>com.github.messenger4j</groupId>
  <artifactId>messenger4j</artifactId>
  <version>0.8.0</version>
</dependency>

To add a dependency using Gradle:

dependencies {
  compile 'com.github.messenger4j:messenger4j:0.8.0'
}

Showcase

For a complete sample application showcasing many features of the Messenger Platform take a look at the messenger4j-spring-boot-quickstart-template. You can use it to quickly bootstrap your chatbot projects.

Examples

For almost all supported features you can take a look at the integration tests (src/test/java/.../test/integration) for a working example.

Receiving

Let's see how to handle an inbound text message:

String payload = ... // callback request body
String signature = ... // 'X-Hub-Signature' request header

// JDK 8 version
MessengerReceiveClient receiveClient = MessengerPlatform.newReceiveClientBuilder("APP_SECRET", "VERIFICATION_TOKEN")
        .onTextMessageEvent(event ->  System.out.printf("%s: %s", event.getSender().getId(), event.getText()))
        .build();

// JDK 7 version
MessengerReceiveClient receiveClient = MessengerPlatform.newReceiveClientBuilder("APP_SECRET", "VERIFICATION_TOKEN")
        .onTextMessageEvent(new TextMessageEventHandler() {
            @Override
            public void handle(TextMessageEvent event) {
                System.out.printf("%s: %s", event.getSender().getId(), event.getText());
            }
        })
        .build();

receiveClient.processCallbackPayload(payload, signature);

But what if you are receiving an image / video / ... attachment?

Either register an AttachmentMessageEventHandler as well:

MessengerReceiveClient receiveClient = MessengerPlatform.newReceiveClientBuilder("APP_SECRET", "VERIFICATION_TOKEN")
        .onTextMessageEvent(event -> {
            System.out.printf("%s: %s", event.getSender().getId(), event.getText());
        })
        .onAttachmentMessageEvent(event -> {
            event.getAttachments().forEach(attachment -> System.out.println(attachment.getType()));
        })
        .build();

or register a FallbackEventHandler that handles all inbound messages or events for which no EventHandler has been registered:

MessengerReceiveClient receiveClient = MessengerPlatform.newReceiveClientBuilder("APP_SECRET", "VERIFICATION_TOKEN")
        .onTextMessageEvent(event -> {
            System.out.printf("%s: %s", event.getSender().getId(), event.getText());
        })
        .fallbackEventHandler(event -> {
            System.out.printf("%s: Sorry, cannot handle your request!" + event.getSender().getId());
        })
        .build();

In addition the following handlers are supported:

• AccountLinkingEventHandler
• EchoMessageEventHandler
• MessageDeliveredEventHandler
• MessageReadEventHandler
• OptInEventHandler
• PostbackEventHandler
• QuickReplyMessageEventHandler

Sending

What's about sending messages back to the user?

Sending a text message is as simple as:

MessengerSendClient sendClient = MessengerPlatform.newSendClientBuilder("PAGE_ACCESS_TOKEN").build();
sendClient.sendTextMessage("RECIPIENT_ID", "Hi there, how are you today?");

And if you want to add Quick Replies to your response, just do the following:

List<QuickReply> quickReplies = QuickReply.newListBuilder()
        .addTextQuickReply("great", "GREAT_PAYLOAD").toList()
        .addTextQuickReply("brilliant", "BRILLIANT_PAYLOAD").imageUrl("http://thumb-up-image.url").toList()
        .addLocationQuickReply().toList()
        .build();
        
sendClient.sendTextMessage("RECIPIENT_ID", "Hi there, how are you today?", quickReplies);

And of course - Templates. Creating them using the fluent builder API is super easy:

ReceiptTemplate receipt = ReceiptTemplate.newBuilder("Stephane Crozatier", "12345678902", "USD", "Visa 2345")
        .orderUrl("http://petersapparel.parseapp.com/order?order_id=123456")
        .timestamp(1428444852L)
        .addElements()
            .addElement("Classic White T-Shirt", 50F)
                .subtitle("100% Soft and Luxurious Cotton")
                .quantity(2)
                .currency("USD")
                .imageUrl("http://petersapparel.parseapp.com/img/whiteshirt.png")
                .toList()
            .addElement("Classic Gray T-Shirt", 25F)
                .subtitle("100% Soft and Luxurious Cotton")
                .quantity(1)
                .currency("USD")
                .imageUrl("http://petersapparel.parseapp.com/img/grayshirt.png")
                .toList()
            .done()
        .addAddress("1 Hacker Way", "Menlo Park", "94025", "CA", "US").street2("").done()
        .addSummary(56.14F).subtotal(75.00F).shippingCost(4.95F).totalTax(6.19F).done()
        .addAdjustments()
            .addAdjustment()
                .name("New Customer Discount")
                .amount(20.00F)
                .toList()
            .addAdjustment()
                .name("$10 Off Coupon")
                .amount(10.00F)
            .toList()
        .done()
        .build();
        
sendClient.sendTemplate("RECIPIENT_ID", receipt);

List<Button> buttons = Button.newListBuilder()
        .addUrlButton("View Website", "https://petersfancybrownhats.com").toList()
        .addPostbackButton("Start Chatting", "DEVELOPER_DEFINED_PAYLOAD").toList()
        .build();

GenericTemplate genericTemplate = GenericTemplate.newBuilder()
        .addElements()
            .addElement("Welcome to Peters Hats")
                .itemUrl("https://petersfancybrownhats.com")
                .imageUrl("https://petersfancybrownhats.com/company_image.png")
                .subtitle("We have got the right hat for everyone.")
                .buttons(buttons)
                .toList()
        .done()
        .build();

sendClient.sendTemplate("RECIPIENT_ID", genericTemplate);

In addition the following methods are available:

• sendSenderAction
• sendImageAttachment
• sendAudioAttachment
• sendVideoAttachment
• sendFileAttachment
• sendBinaryAttachment - for reusable attachments

The Echo Example

MessengerSendClient sendClient = MessengerPlatform.newSendClientBuilder("PAGE_ACCESS_TOKEN").build();
        
MessengerReceiveClient receiveClient = MessengerPlatform.newReceiveClientBuilder("APP_SECRET", "VERIFICATION_TOKEN")
        .onTextMessageEvent(event -> {
            try {
                sendClient.sendTextMessage(event.getSender().getId(), "Echo: " + event.getText());
            } catch (MessengerApiException | MessengerIOException e) {
                // Oops, something went wrong
            }
        })
        .build();

receiveClient.processCallbackPayload(payload, signature);

Things to do

Unordered list of planned improvements:

• comprehensive documentation
• Receive API:
  • Referral support
• Send API:
  • JavaDoc
  • Airline Templates
  • upload Binary Attachments
• Payment support
• Checkbox Plugin support

License

This project is licensed under the terms of the MIT license.