Add reCaptcha I m not a robot in JAVA websites

 

1. First login to google and go to the link https://www.google.com/recaptcha/admin#list You can see the Register a new site form as below.
   
   
2. 2.1 Fill any Label
   2.1 Enter your host name, Now I am giving domain name as localhost. You can enter your website name if you want to host this in your website.
3. After Registering new site, You will get a Site key and Secret key as Shown
4. Project Structure in Eclipse IDE,
5. LoginServlet.java

   package com.chillyfacts.com;
   import java.io.IOException;
   import java.io.PrintWriter;
   import javax.servlet.RequestDispatcher;
   import javax.servlet.ServletException;
   import javax.servlet.http.HttpServlet;
   import javax.servlet.http.HttpServletRequest;
   import javax.servlet.http.HttpServletResponse;
   import com.chillyfacts.com.utils.VerifyRecaptcha;
   /**
    * Servlet implementation class LoginServlet
    */
   public class LoginServlet extends HttpServlet {
   	private static final long serialVersionUID = -6506682026701304964L;
   	protected void doPost(HttpServletRequest request,
   			HttpServletResponse response) throws ServletException, IOException {
   		//hardcoded user name and password
   		String userID = "jinu" ;
   		String password = "jawad";
   		// get request parameters for userID and password
   		String user = request.getParameter("user");
   		String pwd = request.getParameter("pwd");
   		// get reCAPTCHA request param
   		String gRecaptchaResponse = request
   				.getParameter("g-recaptcha-response");
   		System.out.println(gRecaptchaResponse);
   		boolean verify = VerifyRecaptcha.verify(gRecaptchaResponse);
   		// get servlet config init params
   		// logging example
   		System.out.println("User=" + user + "::password=" + pwd + "::Captcha Verify"+verify);
   		if (userID.equals(user) && password.equals(pwd) && verify) {
   			response.sendRedirect("LoginSuccess.jsp");
   		} else {
   			RequestDispatcher rd = getServletContext().getRequestDispatcher(
   					"/login.html");
   			PrintWriter out = response.getWriter();
   			if (verify) {
   				out.println("<font color=red>Either user name or password is wrong.</font>");
   			} else {
   				out.println("<font color=red>You missed the Captcha.</font>");
   			}
   			rd.include(request, response);
   		}
   	}
   }
   

6. VerifyRecaptcha.java

   package com.chillyfacts.com.utils;
   import java.io.BufferedReader;
   import java.io.DataOutputStream;
   import java.io.IOException;
   import java.io.InputStreamReader;
   import java.io.StringReader;
   import java.net.URL; 
   import javax.json.Json; 
   import javax.json.JsonObject;
   import javax.json.JsonReader;
   import javax.net.ssl.HttpsURLConnection;
   public class VerifyRecaptcha {
   	public static final String url = "https://www.google.com/recaptcha/api/siteverify";
   	public static final String secret = "Update your Secret key here";
   	private final static String USER_AGENT = "Mozilla/5.0";
   	public static boolean verify(String gRecaptchaResponse) throws IOException {
   		if (gRecaptchaResponse == null || "".equals(gRecaptchaResponse)) {
   			return false;
   		}
   		try{
   		URL obj = new URL(url);
   		HttpsURLConnection con = (HttpsURLConnection) obj.openConnection();
   		// add reuqest header
   		con.setRequestMethod("POST");
   		con.setRequestProperty("User-Agent", USER_AGENT);
   		con.setRequestProperty("Accept-Language", "en-US,en;q=0.5");
   		String postParams = "secret=" + secret + "&response="
   				+ gRecaptchaResponse;
   		// Send post request
   		con.setDoOutput(true);
   		DataOutputStream wr = new DataOutputStream(con.getOutputStream());
   		wr.writeBytes(postParams);
   		wr.flush();
   		wr.close();
   		int responseCode = con.getResponseCode();
   		System.out.println("\nSending 'POST' request to URL : " + url);
   		System.out.println("Post parameters : " + postParams);
   		System.out.println("Response Code : " + responseCode);
   		BufferedReader in = new BufferedReader(new InputStreamReader(
   				con.getInputStream()));
   		String inputLine;
   		StringBuffer response = new StringBuffer();
   		while ((inputLine = in.readLine()) != null) {
   			response.append(inputLine);
   		}
   		in.close();
   		// print result
   		System.out.println(response.toString());
   		//parse JSON response and return 'success' value
   		JsonReader jsonReader = Json.createReader(new StringReader(response.toString()));
   		JsonObject jsonObject = jsonReader.readObject();
   		jsonReader.close();
   		return jsonObject.getBoolean("success");
   		}catch(Exception e){
   			e.printStackTrace();
   			return false;
   		}
   	}
   }

7. web.xml

   <?xml version="1.0" encoding="UTF-8"?>
   <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    	xmlns="http://java.sun.com/xml/ns/javaee"
    	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
    	id="WebApp_ID" version="3.0">
    	<display-name>LoginExample</display-name>
    	<welcome-file-list>
    		<welcome-file>login.html</welcome-file>
   	 </welcome-file-list>
    	<servlet>
    		<servlet-name>LoginServlet</servlet-name>
    		<servlet-class>com.chillyfacts.com.LoginServlet</servlet-class>
    	</servlet>
    	<servlet-mapping>
    		<servlet-name>LoginServlet</servlet-name>
    		<url-pattern>/LoginServlet/*</url-pattern>
    	</servlet-mapping>
   </web-app>
   

8. login.html

   <!DOCTYPE html>
   <html>
   <head>
   <meta charset="US-ASCII">
   <title>Login Page</title>
   <script src="https://www.google.com/recaptcha/api.js"></script>
   </head>
   <body>
        <form action="LoginServlet" method="post">
         Username: <input type="text" name="user"> <br>
         Password:<input type="password" name="pwd"> <br>
         <div class="g-recaptcha"
               data-sitekey="Update your Site key here"></div>
         <br> <input type="submit" value="Login">
         </form>
   </body>
   </html>
   

9. LoginSuccess.jsp

   <%@ page language="java" contentType="text/html; charset=US-ASCII"
   pageEncoding="US-ASCII"%>
   <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
   <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
    <title>Login Success Page</title>
    </head>
    <body>
    <h3>Login successful.</h3>
    <a href="login.html">Login Page</a>
    </body>
    </html>