JSP实现登录功能之添加验证码


            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中文源码网网站的支持！