Java Amplitude Service for sending Amplitude events server side. Uses Jackson for JSON serialization.

AmplitudeService.java

import com.fasterxml.jackson.annotation.JsonInclude.Include;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.PropertyNamingStrategy;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URI;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import javax.ws.rs.core.UriBuilder;

public class AmplitudeService {

    private final String apiKey;
    private final ObjectMapper objectMapper;

    public AmplitudeService(String apiKey) {

        objectMapper = new ObjectMapper();
        objectMapper.setPropertyNamingStrategy(PropertyNamingStrategy.CAMEL_CASE_TO_LOWER_CASE_WITH_UNDERSCORES);
        objectMapper.setSerializationInclusion(Include.NON_NULL);
        this.apiKey = apiKey;
    }

    public void sendEvent(AmplitudeEvent... events) throws IOException {
        List<AmplitudeEvent> request = Arrays.asList(events);

        URI apiUri = UriBuilder.fromUri("https://api.amplitude.com/httpapi")
                .queryParam("api_key", apiKey)
                .queryParam("event", URLEncoder.encode(objectMapper.writeValueAsString(request),"UTF-8"))
                .build();

        HttpURLConnection connection = (HttpURLConnection)apiUri.toURL().openConnection();
        StringBuilder response = new StringBuilder();
        String inputLine;
        try (BufferedReader in = new BufferedReader(
                (connection.getResponseCode() == 200)
                ? new InputStreamReader(connection.getInputStream()) 
                : new InputStreamReader(connection.getErrorStream()) )) {

            while ((inputLine = in.readLine()) != null) {
                response.append(inputLine);
            }
        }

        if (!"success".equals(response.toString())) {
            throw new IOException("Amplitude Error: " + response.toString());
        }
    }

    public static class AmplitudeEvent {

        private String userId;
        private String eventType;
        private Long time;
        private HashMap<String, Object> eventProperties;
        private HashMap<String, Object> userProperties;
        private Float revenue;
        private Float locationLat;
        private Float locationLng;

        public String getUserId() {
            return userId;
        }

        public void setUserId(String userId) {
            this.userId = userId;
        }

        public String getEventType() {
            return eventType;
        }

        public void setEventType(String eventType) {
            this.eventType = eventType;
        }

        public Long getTime() {
            return time;
        }

        public void setTime(Long time) {
            this.time = time;
        }

        public HashMap<String, Object> getEventProperties() {
            return eventProperties;
        }

        public void setEventProperties(HashMap<String, Object> eventProperties) {
            this.eventProperties = eventProperties;
        }

        public HashMap<String, Object> getUserProperties() {
            return userProperties;
        }

        public void setUserProperties(HashMap<String, Object> userProperties) {
            this.userProperties = userProperties;
        }

        public Float getRevenue() {
            return revenue;
        }

        public void setRevenue(Float revenue) {
            this.revenue = revenue;
        }

        public Float getLocationLat() {
            return locationLat;
        }

        public void setLocationLat(Float locationLat) {
            this.locationLat = locationLat;
        }

        public Float getLocationLng() {
            return locationLng;
        }

        public void setLocationLng(Float locationLng) {
            this.locationLng = locationLng;
        }
    }

}