ValidationServlet.java

package com.acme;

import com.prevoty.*;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

public class ValidationServlet extends HttpServlet {
    private PrevotyClient client;

    public ValidationServlet() {
        super();
        this.client = new PrevotyClient("valid api key", "https://api.prevoty.com/1", 10000);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.addHeader("Content-Type", "text/html");
        PrintWriter out = response.getWriter();

        out.println("<form action='/validation' method='post'>" +
                "Credit Card Number Validation: " +
                "<input type='text' name='creditCardNumber'>" +
                "<input type='submit' />" +
                "</form>");
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.addHeader("Content-Type", "text/html");
        PrintWriter out = response.getWriter();

        String creditCardNumber = request.getParameter("creditCardNumber");

        if (creditCardNumber == null) {
            out.println("A credit card number is required");
            return;
        }

        InputValidationResult result;

        try {
            result = client.ValidateCreditCard(creditCardNumber);
        } catch (Exception e) {
            e.printStackTrace();
            out.println("An error occurred while validating your credit card number");
            return;
        }

        out.println("The credit number is " + (result.matched ? "valid" : "invalid"));
    }
}