ImageServlet.java
package cn.hist.test.servlet; import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.image.BufferedImage; import java.io.IOException; import java.util.Random; import javax.imageio.ImageIO; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; public class ImageServlet extends HttpServlet{ // 生成随机颜色 Color getRandColor(int fc, int bc) { Random random = new Random(); if (fc > 255) fc = 255; if (bc > 255) bc = 255; int r = fc + random.nextInt(bc - fc); int g = fc + random.nextInt(bc - fc); int b = fc + random.nextInt(bc - fc); return new Color(r, g, b); } public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException{ HttpSession session = request.getSession(); // 设置图形验证码中字符串的字体和大小 Font myFont = new Font("", Font.PLAIN, 25); // 阻止生成的页面内容被缓存，保证每次重新生成随机验证码 response.setHeader("Pragma", "No-cache"); response.setHeader("Cache-Control", "no-cache"); response.setDateHeader("Expires", 0); response.setContentType("image/jpeg"); // 指定图形验证码图片的大小 int width = 64, height = 41; // 生成一张新图片 BufferedImage image=new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB); Graphics g=image.getGraphics(); //通过缓冲区创建一个画布 Random random = new Random(); g.setColor(getRandColor(200, 250));//为画布创建背景颜色 g.fillRect(0, 0, width,height); //fillRect:填充指定的矩形 g.setColor(new Color(82, 82, 82)); //字体颜色 //g.drawRect(0, 0, width - 1, height - 1); //产生边框 g.setFont(myFont); // 随机生成线条，让图片看起来更加杂乱 g.setColor(getRandColor(160, 200)); for (int i = 0; i < 155; i++) { int x = random.nextInt(width - 1);// 起点的x坐标 int y = random.nextInt(height - 1);// 起点的y坐标 int x1 = random.nextInt(6) + 1;// x轴偏移量 int y1 = random.nextInt(12) + 1;// y轴偏移量 g.drawLine(x, y, x + x1, y + y1); } // 随机生成线条，让图片看起来更加杂乱 for (int i = 0; i < 70; i++) { int x = random.nextInt(width - 1); int y = random.nextInt(height - 1); int x1 = random.nextInt(12) + 1; int y1 = random.nextInt(6) + 1; g.drawLine(x, y, x - x1, y - y1); } // 该变量用来保存系统生成的随机字符串 String sRand = ""; for (int i = 0; i < 6; i++) { // 取得一个随机字符 String tmp = getRandomChar(); sRand += tmp; // 将系统生成的随机字符添加到图形验证码图片上 g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110))); //将验证码显示在图像中 g.drawString(tmp, 15 * i + 3, 30); //字体距左边及上边的距离 } // 将系统生成的图形验证码添加 session.setAttribute("rand", sRand); g.dispose(); // 输出图形验证码图片 ImageIO.write(image, "JPEG", response.getOutputStream()); } // 随机生成一个字符 private String getRandomChar() { int rand = (int) Math.round(Math.random() * 2);// 将0～2的小数四舍五入生成整数 long itmp = 0; char ctmp = 'u0000'; // 根据rand的值来决定是生成一个大写字母、小写字母和数字 switch (rand) { // 生成大写字母的情形 case 1: itmp = Math.round(Math.random() * 25 + 65); ctmp = (char) itmp; return String.valueOf(ctmp); // 生成小写字母 case 2: itmp = Math.round(Math.random() * 25 + 97); ctmp = (char) itmp; return String.valueOf(ctmp); // 生成数字 default: itmp = Math.round(Math.random() * 9); return String.valueOf(itmp); } } }
index.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> <html> <head> <meta charset="utf-8"> <base href="<%=basePath%>"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <title>Test</title> <link rel="stylesheet" href=""> <script> //刷新验证码 function refresh() { var time = new Date().getTime(); document.getElementById("imagecode").src = "ImageServlet?d=" + time; } </script> </head> <body> <form action="ImageCompare"> <p> <label for="icode">验证码</label><input type="text" name="icode" id="icode" placeholder="请输入验证码" /><img alt="验证码" id="imagecode" class="imagecode" src="ImageServlet" onclick="refresh()" /><a href="javascript:void(0);" onclick="refresh()">看不清？</a> </p> </form> </body> </html>
web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> <display-name></display-name> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <servlet> <servlet-name>ImageServlet</servlet-name> <servlet-class>cn.hist.test.servlet.ImageServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>ImageServlet</servlet-name> <url-pattern>/ImageServlet</url-pattern> </servlet-mapping> </web-app>
ImageCompare.java
package cn.hist.test.servlet; import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; /** * 比较输入的验证码是否正确 * @author Administrator * */ public class ImageCompare extends HttpServlet{ @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { PrintWriter out = resp.getWriter(); HttpSession session = req.getSession(); // 获取验证码中的字符 String rand = (String) session.getAttribute("rand"); System.out.println(rand); String icode = req.getParameter("icode"); System.out.println(icode); if (icode.equals(rand)) { out.print("success"); } else { out.print("fail"); } } }
将rand与icode都转换成大写或小写再进行比较，实现输入验证码时不区分大小写