快捷導(dǎo)航

Servlet+JDBC實現(xiàn)登陸功能的小例子(帶驗證碼)

更新時間：2020年06月24日 09:58:48 作者：大象大象你的鼻子怎么那么長

這篇文章主要介紹了Servlet+JDBC實現(xiàn)登陸功能的小例子(帶驗證碼)，文中通過示例代碼介紹的非常詳細，對大家的學(xué)習(xí)或者工作具有一定的參考學(xué)習(xí)價值，需要的朋友們下面隨著小編來一起學(xué)習(xí)學(xué)習(xí)吧

案例需求：訪問帶有驗證碼的登錄頁面login.jsp用戶輸入用戶名，密碼以及驗證碼。如果用戶名和密碼輸入有誤，跳轉(zhuǎn)登錄頁面，提示:用戶名或密碼錯誤如果驗證碼輸入有誤，跳轉(zhuǎn)登錄頁面，提示：驗證碼錯誤如果全部輸入正確，則跳轉(zhuǎn)到主頁success.jsp，顯示：用戶名,歡迎您分析

步驟

文件樹展示

1.配置文件和jar包在上個案例均有配置過，需要改的有：User類新增驗證碼成員變量，數(shù)據(jù)庫增加了一個驗證碼字段（無用，只是為了UserDao包把查找到的數(shù)據(jù)值導(dǎo)入到User類不出錯）。

2.登陸界面

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
  <title>login</title>
  <script>
    window.onload = function(){
      document.getElementById("img").onclick = function(){
        this.src="/CaS/checkCodepic?time="+new Date().getTime();
      }
    }
  </script>
  <style>
    div{
      color: red;
    }
  </style>
</head>
<body>

  <form action="/CaS/loginServlet" method="post">
    <table>
      <tr>
        <td>用戶名</td>
        <td><input type="text" name="username"></td>
      </tr>
      <tr>
        <td>密碼</td>
        <td><input type="password" name="password"></td>
      </tr>
      <tr>
        <td>驗證碼</td>
        <td><input type="text" name="checkCode"></td>
      </tr>
      <tr>
        <td colspan="2"><img id="img" src="/CaS/checkCodepic"></td>
      </tr>
      <tr>
        <td colspan="2"><input type="submit" value="登錄"></td>
      </tr>
    </table>


  </form>


  <div><%=request.getAttribute("cc_error") == null ? "" : request.getAttribute("cc_error")%></div>
  <div><%=request.getAttribute("login_error") == null ? "" : request.getAttribute("login_error") %></div>

</body>
</html>

3.驗證碼，畫了個驗證碼，每次都把隨機數(shù)加入session中以便進行對比

package Test;

import javax.imageio.ImageIO;
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 java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

@WebServlet("/checkCodepic")
public class CheckCodepic extends HttpServlet {
  @Override
  protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    int width=100;
    int height=50;
    //創(chuàng)建圖片對象
    BufferedImage image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);

    //美化圖片
    //創(chuàng)建畫筆
    Graphics g = image.getGraphics();
    //畫筆顏色
    g.setColor(Color.pink);
    //畫個矩形，填充為粉紅色
    g.fillRect(0,0,width,height);
    //給矩形加邊框
    g.setColor(Color.blue);
    g.drawRect(0,0,width-1,height-1);
    //寫字母或數(shù)字
    g.setColor(Color.green);
    String str="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
    Random rd=new Random();
    StringBuilder sb=new StringBuilder();
    for(int i=1;i<=4;i++){
      int index = rd.nextInt(str.length());
      char c = str.charAt(index);
      sb.append(c);
      g.drawString(c+"",width/5*i,height/2);
    }
    String checkCode_session = sb.toString();
    //將驗證碼存入session
    req.getSession().setAttribute("checkCode_session",checkCode_session);
    //加干擾線
    g.setColor(Color.blue);
    for(int i=1;i<=10;i++){
      int x1 = rd.nextInt(width);
      int x2 = rd.nextInt(width);
      int y1 = rd.nextInt(height);
      int y2 = rd.nextInt(height);
      g.drawLine(x1,y1,x2,y2);
    }

    //輸出展示
    ImageIO.write(image,"jpg",resp.getOutputStream());
  }

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

4.loginServlet類，用來判斷驗證碼和用戶名密碼是否正確，注意先判斷驗證碼；注意重定向和請求轉(zhuǎn)發(fā)的不同，還有session的應(yīng)用。

package Test;

import Test.dao.UserDao;
import Test.userclass.User;
import org.apache.commons.beanutils.BeanUtils;

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 java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.util.Map;

@WebServlet("/loginServlet")
public class loginServlet extends HttpServlet {
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    //設(shè)置request編碼
    request.setCharacterEncoding("utf-8");
    //獲取參數(shù)
//    String username = request.getParameter("username");
//    String password = request.getParameter("password");
//    String checkCode = request.getParameter("checkCode");
//    User user=new User();
//    user.setUsername(username);
//    user.setPassword(password);
//    user.setCheckCode(checkCode);
    Map<String, String[]> parameterMap = request.getParameterMap();
    User user=new User();
    try {
      BeanUtils.populate(user,parameterMap);
    } catch (IllegalAccessException e) {
      e.printStackTrace();
    } catch (InvocationTargetException e) {
      e.printStackTrace();
    }
    UserDao userDao=new UserDao();
    //先判斷驗證碼是否正確
    String checkCode_session = (String)request.getSession().getAttribute("checkCode_session");
    request.getSession().removeAttribute("checkCode_session");
    if(checkCode_session!=null && checkCode_session.equalsIgnoreCase(user.getCheckCode())){//忽略大小寫
      //如果正確，判斷用戶名密碼是否正確
      User login = userDao.login(user);
      if(login!=null){
        //登陸成功，存儲用戶信息
        request.getSession().setAttribute("username",login.getUsername());
        //重定向到success.jsp
        response.sendRedirect(request.getContextPath()+"/success.jsp");

      }else{//登陸失敗，轉(zhuǎn)發(fā)到登陸界面
        request.setAttribute("login_error","用戶名或密碼不正確");
        request.getRequestDispatcher("/login.jsp").forward(request,response);

      }
    }else{ //如果不正確，轉(zhuǎn)發(fā)到登陸界面
      request.setAttribute("cc_error","驗證碼不正確");
      request.getRequestDispatcher("/login.jsp").forward(request,response);

    }
  }

  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    this.doPost(request, response);
  }
}

5.成功登陸界面

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
  <title>Title</title>
</head>
<body>

  <h1><%=request.getSession().getAttribute("username")%>,歡迎您</h1>

</body>
</html>

結(jié)果

登陸界面