TestServlet

package com.clouway.servlets;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.text.CollationKey;
import java.util.UUID;

/**
 * @author Ivan Genchev ([email protected])
 */
public class TestServlet extends HttpServlet {

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


    // on login ...
    String sid = getSid(req);
    if (sid == null) {
      UUID uuid = new UUID(10,5);
      String randomValue = "[email protected]" + uuid.randomUUID().toString() + "abc";
      sid = sha1(randomValue);
      resp.addCookie(new Cookie("sid", sid));

      // register session in database (userid, sid, expirationTime);

    }



    // on login ...
//    sessions.refresh(sid); // or redirect to login page in case of expiration or unknown sid was provided

//    resp.addCookie(new Cookie("test", "value1"));

  }

  private String getSid(HttpServletRequest req) {
    Cookie[] cookies = req.getCookies();
    if (cookies == null) {
      return null;
    }

    for (Cookie each : cookies) {
      if (each.getName().equalsIgnoreCase("sid")) {
        return each.getValue();
      }
    }

    return null;
  }

  static String sha1(String input) {
    MessageDigest mDigest = null;
    try {
      mDigest = MessageDigest.getInstance("SHA1");
    } catch (NoSuchAlgorithmException e) {
      return "";
    }

    byte[] result = mDigest.digest(input.getBytes());
    StringBuffer sb = new StringBuffer();
    for (int i = 0; i < result.length; i++) {
      sb.append(Integer.toString((result[i] & 0xff) + 0x100, 16).substring(1));
    }

    return sb.toString();
  }

}