JSP实现登录功能之添加验证码

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我是靠谱客的博主苹果棒球，最近开发中收集的这篇文章主要介绍JSP实现登录功能之添加验证码，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

jsp登陆验证，网页登陆验证带验证码校验，登录功能之添加验证码

part_1：专门用于生成一个验证码图片的类:VerificationCode.Java

package cn.mike.javase.test; 
import java.awt.Color; 
import java.awt.Font; 
import java.awt.Graphics2D; 
import java.awt.image.BufferedImage; 
import java.io.File; 
import java.io.FileNotFoundException; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import java.io.OutputStream; 
import java.util.Random; 
import javax.imageio.ImageIO; 
import org.junit.Test; 
/** 
 * @author : Administrator 
 * @function : 这是用来测试随机生成验证码图片的类； 
 */ 
public class VerificationCode { 
  /** 
   * 单元测试，试一下能不能自动生成验证码图片 
   */ 
  // 这个函数是单元测试时使用的，这里private一下外面就调用不到了； 
  /* @Test */ 
  /* public */private void test_fun() { 
    VerificationCode vc = new VerificationCode(); 
    BufferedImage image = vc.getImage(); 
    try { 
      // 生成验证码图片，并保存到指定的路径 
      VerificationCode.output(image, new FileOutputStream(new File( 
          ".\\image\\vcode_2.jpg"))); 
    } catch (FileNotFoundException e) { 
      e.printStackTrace(); 
    } 
    // 将随机生成的文本内容输出到控制台，用于校验 
    System.out.println(vc.getText()); 
  } 
  private int w = 70;// 宽 
  private int h = 35;// 高 
  private String text;// 文本内容(验证码字符串) 
  private Random r = new Random(); 
  private String[] fontNames = { "宋体", "华文楷体", "黑体", "微软雅黑", "楷体_GB2312" }; 
  // 随机字符集合中不包括0和o，O，1和l，因为这些不易区分 
  private String codes = "23456789abcdefghijkmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYXZ"; 
  // 验证码图片的背景色：白色 
  private Color bgColor = new Color(255, 255, 255); 
  /** 
   * 返回一个验证码图片buffer对象：BufferedImage 
   */ 
  public BufferedImage getImage() { 
    BufferedImage image = createImage(); 
    // 获取绘图环境（画笔工具） 
    Graphics2D g2 = (Graphics2D) image.getGraphics(); 
    // sb ： 用来保存验证码字符串文本内容 
    StringBuilder sb = new StringBuilder(); 
    for (int i = 0; i < 4; ++i) {// 随机生成4个字符 
      String s = randomChar() + ""; 
      sb.append(s); 
      float x = i * 1.0F * w / 4; 
      g2.setFont(randomFont()); 
      g2.setColor(randomColor()); 
      g2.drawString(s, x, h - 5); 
    } 
    this.text = sb.toString();// 记录验证码文本内容 
    drawLine(image);// 画干扰线 
    return image; 
  } 
  /** 
   * @return 获取验证码文本内容 
   */ 
  public String getText() { 
    return text; 
  } 
  /** 
   * @param image 
   * @param out 
   *      将文本写到指定的输出流。比如本测试中FileOutputStream指定的保存路径 
   */ 
  public static void output(BufferedImage image, OutputStream out) { 
    try { 
      ImageIO.write(image, "jpeg", out); 
    } catch (IOException e) { 
      e.printStackTrace(); 
    } 
  } 
  private void drawLine(BufferedImage image) { 
    Graphics2D g2 = (Graphics2D) image.getGraphics(); 
    for (int i = 0; i < 3; ++i) {// 画3条干扰线 
      int x1 = r.nextInt(w); 
      int y1 = r.nextInt(h); 
      int x2 = r.nextInt(w); 
      int y2 = r.nextInt(h); 
      g2.setColor(Color.BLUE); 
      g2.drawLine(x1, y1, x2, y2); 
    } 
  } 
  private Color randomColor() { 
    int red = r.nextInt(150); 
    int green = r.nextInt(150); 
    int blue = r.nextInt(150); 
    return new Color(red, green, blue); 
  } 
  private Font randomFont() { 
    int index = r.nextInt(fontNames.length); 
    String fontName = fontNames[index]; 
    int style = r.nextInt(4); 
    int size = r.nextInt(5) + 24; 
    return new Font(fontName, style, size); 
  } 
  private char randomChar() { 
    int index = r.nextInt(codes.length()); 
    return codes.charAt(index); 
  } 
  private BufferedImage createImage() { 
    BufferedImage image = new BufferedImage(w, h, 
        BufferedImage.TYPE_INT_RGB); 
    Graphics2D g2 = (Graphics2D) image.getGraphics(); 
    g2.setColor(this.bgColor); 
    g2.fillRect(0, 0, w, h); 
    return image; 
  } 
}

part_2:登录界面：Login.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> 
<% 
  String path = request.getContextPath(); 
  String basePath = request.getScheme() + "://" 
      + request.getServerName() + ":" + request.getServerPort() 
      + path + "/"; 
%> 
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 
<html> 
  <head> 
    <base href="<%=basePath%>"> 
    <title>My JSP 'Login.jsp' starting page</title> 
    <meta http-equiv="pragma" content="no-cache"> 
    <meta http-equiv="cache-control" content="no-cache"> 
    <meta http-equiv="expires" content="0"> 
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> 
    <meta http-equiv="description" content="This is my page"> 
    <!-- 
  <link rel="stylesheet" type="text/css" href="styles.css"> 
  --> 
    <script type="text/javascript"> 
  function _change_verity_code() { 
    var imgElem = document.getElementById("img_src"); 
    //添加一个请求参数a是因为，通常浏览器都有缓存，点击换一张的时候没反应，所以加一个请求参数，获取当前请求时间，可以精确到毫秒，所以每次请求的参数都不同，所以浏览器有缓存也不妨碍； 
    imgElem.src = "/ServletDemoProject/servlet/GetVerificationCodeServlet?a=" 
        + new Date().getTime(); 
  } 
</script> 
  </head> 
  <% 
    String fdbkMsg = (String) request.getAttribute("fdbkMsg"); 
    if (null == fdbkMsg) { 
      fdbkMsg = ""; 
    } 
  %> 
  <% 
    Boolean logedIn = (Boolean) session.getAttribute("logedIn"); 
    if (null == logedIn) { 
      logedIn = false; 
    } else if (logedIn) { 
      //如果在本次会话已经登陆，直接重定向到success-page-1 
      response 
          .sendRedirect("/ServletDemoProject/LOGIN-DEMO/success-page-1.jsp"); 
    } 
  %> 
  <% 
    String username = ""; 
    Cookie[] cookies = request.getCookies(); 
    if ((null != cookies) && (cookies.length > 0)) { 
      for (Cookie c : cookies) { 
        if ("admin".equals(c.getValue())) { 
          username = "admin"; 
          break; 
        } 
      } 
    }//end if-condition 
  %> 
  <body> 
    <br> 
    <div align="center"> 
      请登录: 
      <br> 
      <form action="/ServletDemoProject/servlet/LoginVerificationServlet" 
        method="post"> 
        <div> 
          用户名： 
          <input type="text" name="username" value="<%=username%>" /> 
          <br> 
        </div> 
        <div> 
          密  码： 
          <input type="password" name="password" /> 
          <br> 
        </div> 
        <div> 
          验证码： 
          <input type="text" name="code_text" size="3" /> 
          <img src="/ServletDemoProject/servlet/GetVerificationCodeServlet" 
            id="img_src" /> 
          <a href="javascript：_change_verity_code()">换一张</a> 
          <br> 
        </div> 
        <div> 
          <font color='red'><%=fdbkMsg%></font> 
          <br> 
        </div> 
        <div> 
          <input type="submit" value="提交" /> 
          <br> 
        </div> 
      </form> 
    </div> 
  </body> 
</html>

part_3:处理登录校验的servlet ：LoginVerificationServlet.java

package cn.mike.servlet.test_1212; 
import java.awt.image.BufferedImage; 
import java.io.IOException; 
import javax.servlet.ServletException; 
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
import cn.mike.javase.test.VerificationCode; 
public class GetVerificationCodeServlet extends HttpServlet { 
  private static final long serialVersionUID = -3520994675366100452L; 
  public void doGet(HttpServletRequest request, HttpServletResponse response) 
      throws ServletException, IOException { 
    // 1.新建一个VerificationCode类； 
    VerificationCode vc = new VerificationCode(); 
    // 2.从VerificationCode类中获取BufferedImage对象； 
    BufferedImage bufImage = vc.getImage(); 
    // 3.同时获取验证码中的文本内容，并放到session域中， 用于校验； 
    String code_text = vc.getText(); 
    request.getSession().setAttribute("code_text", code_text); 
    // 4.将生成的图片输出到客户端浏览器 
    VerificationCode.output(bufImage, response.getOutputStream()); 
  }// end method-doGet 
  public void doPost(HttpServletRequest request, HttpServletResponse response) 
      throws ServletException, IOException { 
    // do same as GET-method : 
    doGet(request, response); 
  }// end method-doPost 
}

part_4:成功登陆后的提示界面1：success-page-1.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> 
<% 
  String path = request.getContextPath(); 
  String basePath = request.getScheme() + "://" 
      + request.getServerName() + ":" + request.getServerPort() 
      + path + "/"; 
%> 
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 
<html> 
  <head> 
    <base href="<%=basePath%>"> 
    <title>My JSP 'success-page-1.jsp' starting page</title> 
    <meta http-equiv="pragma" content="no-cache"> 
    <meta http-equiv="cache-control" content="no-cache"> 
    <meta http-equiv="expires" content="0"> 
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> 
    <meta http-equiv="description" content="This is my page"> 
    <!-- 
  <link rel="stylesheet" type="text/css" href="styles.css"> 
  --> 
  </head> 
  <% 
    String username = (String) session.getAttribute("username"); 
    if (null == username) { 
      //如果username为空值，说明不是通过正常渠道来的，转发到Login页面； 
      request.setAttribute("fdbkMsg", "别想走后门进来，赶紧登录！"); 
      request.getRequestDispatcher("/LOGIN-DEMO/Login.jsp").forward( 
          request, response); 
    } 
  %> 
  <body> 
    <br> 
    <%=username%>已经成功登陆。 
    <br> 
    <font>您可以选择浏览：</font> 
    <br> 
    <a href="/ServletDemoProject/LOGIN-DEMO/success-page-2.jsp">点这儿有精彩.</a> 
    <br> 
    <a href="/ServletDemoProject/LOGIN-DEMO/success-page-2.jsp">点这儿更精彩.</a> 
    <br /> 
    <a href="/ServletDemoProject/LOGIN-DEMO/success-page-2.jsp">你敢点这儿吗.</a> 
    <br /> 
  </body> 
</html>

part_5:成功登陆后的提示界面1：success-page-2.jsp

<%@ page language="java" import="java.util.Date" pageEncoding="UTF-8"%> 
<%@ page language="java" import="java.text.SimpleDateFormat"%> 
<% 
  String path = request.getContextPath(); 
  String basePath = request.getScheme() + "://" 
      + request.getServerName() + ":" + request.getServerPort() 
      + path + "/"; 
%> 
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 
<html> 
  <head> 
    <base href="<%=basePath%>"> 
    <title>My JSP 'success-page-2.jsp' starting page</title> 
    <meta http-equiv="pragma" content="no-cache"> 
    <meta http-equiv="cache-control" content="no-cache"> 
    <meta http-equiv="expires" content="0"> 
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> 
    <meta http-equiv="description" content="This is my page"> 
    <!-- 
  <link rel="stylesheet" type="text/css" href="styles.css"> 
  --> 
  </head> 
  <% 
    String username = (String) session.getAttribute("username"); 
    if (null == username) { 
      request.setAttribute("fdbkMsg", "呵呵嗒，这里是你来的地方吗？快登陆！"); 
      //转发到登录界面: 
      request.getRequestDispatcher("/LOGIN-DEMO/Login.jsp").forward( 
          request, response); 
    } 
    SimpleDateFormat sDateFormat = new SimpleDateFormat("a"); 
    Date today = new Date(); 
    String am_pm_str = sDateFormat.format(today); 
    String am_pm_str_in_chinese = ""; 
    if ("am".equalsIgnoreCase(am_pm_str)) { 
      am_pm_str_in_chinese = "上午"; 
    } else 
      am_pm_str_in_chinese = "下午"; 
    // set null; 
    sDateFormat = null; 
    today = null; 
    am_pm_str = null; 
  %> 
  <body> 
    <br /> 
    <font><b><%=username%><%=am_pm_str_in_chinese%>好，能来到页面2真不简单.</b> 
    </font> 
  </body> 
</html>

以上所述是小编给大家介绍的JSP实现登录功能之添加验证码，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对脚本之家网站的支持！