Hướng dẫn sử dụng Google reCAPTCHA trong ứng dụng Web Java

<?xml version="1.0" encoding="UTF-8"?>
<web-app
    xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
                http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
    version="3.0">

 
  <display-name>Archetype Created Web Application</display-name>
 
</web-app>

<project xmlns="http://maven.apache.org/POM/4.0.0"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
                       http://maven.apache.org/maven-v4_0_0.xsd">
                       
   <modelVersion>4.0.0</modelVersion>
   <groupId>org.o7planning</groupId>
   <artifactId>reCaptchaDemo</artifactId>
   <packaging>war</packaging>
   <version>0.0.1-SNAPSHOT</version>
   <name>reCaptchaDemo Maven Webapp</name>
   <url>http://maven.apache.org</url>


   <dependencies>
       <dependency>
           <groupId>junit</groupId>
           <artifactId>junit</artifactId>
           <version>3.8.1</version>
           <scope>test</scope>
       </dependency>

       <!-- Servlet Library -->
       <!-- http://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
       <dependency>
           <groupId>javax.servlet</groupId>
           <artifactId>javax.servlet-api</artifactId>
           <version>3.1.0</version>
           <scope>provided</scope>
       </dependency>


       <!-- JSON Library -->
       <!-- http://mvnrepository.com/artifact/org.glassfish/javax.json -->
       <dependency>
           <groupId>org.glassfish</groupId>
           <artifactId>javax.json</artifactId>
           <version>1.0.4</version>
       </dependency>

   </dependencies>


 <build>
       <finalName>reCaptchaDemo</finalName>
       <plugins>
       
           <!-- Config: Maven Tomcat Plugin -->
           <!-- http://mvnrepository.com/artifact/org.apache.tomcat.maven/tomcat7-maven-plugin -->
           <plugin>
               <groupId>org.apache.tomcat.maven</groupId>
               <artifactId>tomcat7-maven-plugin</artifactId>
               <version>2.2</version>
               <!-- Config: contextPath and Port (Default - /reCaptchaDemo : 8080) -->
               <!--
               <configuration>
                   <path>/</path>
                   <port>8899</port>
               </configuration>
               -->    
           </plugin>
       </plugins>
   </build>

</project>

package org.o7planning.tutorial.recaptcha;

public class MyConstants {

   
   public static final String SITE_KEY ="6LelZAsTAAAAAAv1ADYDnq8AzbmPmbMvjh-xhfgB";
   
   public static final String SECRET_KEY ="6LelZAsTAAAAAKa_s6g2yuJzByYlk0FH_6iTkZJC";
   
}

package org.o7planning.tutorial.recaptcha;

import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;

import javax.json.Json;
import javax.json.JsonObject;
import javax.json.JsonReader;
import javax.net.ssl.HttpsURLConnection;

public class VerifyUtils {

	public static final String SITE_VERIFY_URL = //
			"https://www.google.com/recaptcha/api/siteverify";

	public static boolean verify(String gRecaptchaResponse) {
		if (gRecaptchaResponse == null || gRecaptchaResponse.length() == 0) {
			return false;
		}

		try {
			URL verifyUrl = new URL(SITE_VERIFY_URL);

			// Mở một kết nối (Connection) tới URL trên.
			HttpsURLConnection conn = (HttpsURLConnection) verifyUrl.openConnection();

			// Thêm các thông tin Header vào Request chuẩn bị gửi tới server.
			conn.setRequestMethod("POST");
			conn.setRequestProperty("User-Agent", "Mozilla/5.0");
			conn.setRequestProperty("Accept-Language", "en-US,en;q=0.5");

			// Dữ liệu sẽ gửi tới Server.
			String postParams = "secret=" + MyConstants.SECRET_KEY //
					+ "&response=" + gRecaptchaResponse;

			// Send Request
			conn.setDoOutput(true);

			// Lấy Output Stream (Luồng đầu ra) của kết nối tới Server.
			// Ghi dữ liệu vào Output Stream, có nghĩa là gửi thông tin đến Server.
			OutputStream outStream = conn.getOutputStream();
			outStream.write(postParams.getBytes());

			outStream.flush();
			outStream.close();

			// Mã trả lời được trả về từ Server.
			int responseCode = conn.getResponseCode();
			System.out.println("responseCode=" + responseCode);

			// Lấy Input Stream (Luồng đầu vào) của Connection
			// để đọc dữ liệu gửi đến từ Server.
			InputStream is = conn.getInputStream();

			JsonReader jsonReader = Json.createReader(is);
			JsonObject jsonObject = jsonReader.readObject();
			jsonReader.close();

			// ==> {"success": true}
			System.out.println("Response: " + jsonObject);

			boolean success = jsonObject.getBoolean("success");
			return success;
		} catch (Exception e) {
			e.printStackTrace();
			return false;
		}
	}
}

package org.o7planning.tutorial.recaptcha.servlet;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(urlPatterns = "/login")
public class LoginServlet extends HttpServlet {

  private static final long serialVersionUID = 958900029856081978L;

  @Override
  protected void doGet(HttpServletRequest req, HttpServletResponse resp)
          throws ServletException, IOException {
     
      RequestDispatcher dispatcher =
              req.getServletContext().getRequestDispatcher("/WEB-INF/views/loginView.jsp");
     
      dispatcher.forward(req, resp);

  }

  @Override
  protected void doPost(HttpServletRequest req, HttpServletResponse resp)
          throws ServletException, IOException {
      this.doGet(req, resp);
  }

}

package org.o7planning.tutorial.recaptcha.servlet;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.o7planning.tutorial.recaptcha.VerifyUtils;

@WebServlet(urlPatterns = "/doLogin")
public class DoLoginServlet extends HttpServlet {

 private static final long serialVersionUID = 958900029856081978L;

 @Override
 protected void doGet(HttpServletRequest request, HttpServletResponse response)
         throws ServletException, IOException {

     String userName = request.getParameter("userName");
     String password = request.getParameter("password");

     boolean valid = true;
     String errorString = null;

     // Check userName & password
     if (!"tom".equals(userName) || !"tom001".equals(password)) {
         valid = false;
         errorString = "UserName or Password invalid!";
     }

     if (valid) {

         String gRecaptchaResponse = request.getParameter("g-recaptcha-response");

         System.out.println("gRecaptchaResponse=" + gRecaptchaResponse);

         // Verify CAPTCHA.
         valid = VerifyUtils.verify(gRecaptchaResponse);
         if (!valid) {
             errorString = "Captcha invalid!";
         }
     }
     if (!valid) {
         request.setAttribute("errorString", errorString);
         RequestDispatcher dispatcher = //
                     request.getServletContext().getRequestDispatcher("/WEB-INF/views/loginView.jsp");
       
         dispatcher.forward(request, response);
         return;
     } else {
         request.getSession().setAttribute("loginedUser", userName);
         // Redirect to /userInfo
         response.sendRedirect(request.getContextPath()+"/userInfo");
     }
 }

 @Override
 protected void doPost(HttpServletRequest req, HttpServletResponse resp)
                                           throws ServletException, IOException {
     this.doGet(req, resp);
 }

}

package org.o7planning.tutorial.recaptcha.servlet;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(urlPatterns = "/userInfo")
public class UserInfoServlet extends HttpServlet {

	private static final long serialVersionUID = 958900029856081978L;

	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) //
			throws ServletException, IOException {

		if (req.getSession().getAttribute("loginedUser") == null) {
			resp.sendRedirect(req.getContextPath() + "/login");
			return;
		}

		RequestDispatcher dispatcher //
				= req.getServletContext().getRequestDispatcher("/WEB-INF/views/userInfoView.jsp");

		dispatcher.forward(req, resp);

	}

	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) //
			throws ServletException, IOException {

		this.doGet(req, resp);

	}

}

<!-- reCAPTCHA with English language -->
<script src='https://www.google.com/recaptcha/api.js?hl=en'></script>


<!-- reCAPTCHA with Vietnamese language -->
<script src='https://www.google.com/recaptcha/api.js?hl=vi'></script>


<!-- reCAPTCHA with Auto language -->
<script src='https://www.google.com/recaptcha/api.js'></script>

<%@ page language="java" contentType="text/html; charset=UTF-8"
  pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Login</title>

<!-- reCAPTCHA Libary -->
<script src='https://www.google.com/recaptcha/api.js?hl=en'></script>

</head>
<body>

 <h3>Login:</h3>
 
 <p style="color:red;">${errorString}</p>

  <form name="loginForm" method="POST" action="doLogin">
      <table border="0">
          <tr>
              <td>User Name</td>
              <td><input type="text" name="userName" /></td>
          </tr>
          <tr>
              <td>Password</td>
              <td><input type="password" name="password" /></td>
          </tr>
      </table>
     
      <!-- reCAPTCHA -->
      <div class="g-recaptcha"
          data-sitekey="6LelZAsTAAAAAAv1ADYDnq8AzbmPmbMvjh-xhfgB"></div>

      <input type="submit" value="Submit" />

  </form>
  <p style="color:blue;">User Name: tom, Password: tom001</p>

</body>
</html>

<%@ page language="java" contentType="text/html; charset=UTF-8"
  pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<title>User Info</title>


</head>
<body>

 Hello ${loginedUser}

</body>
</html>