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VeVb武林网网站的支持！
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