利用servlet 实现验证码主要继承httpServlet类
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package com.zyc.demo; 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.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; public class DrewImage extends HttpServlet{ /** * */ private static final long serialVersionUID = 1505032428319459075L; private final Font mFont = new Font("Arial Black", Font.PLAIN, 16); private final int IMG_WIDTH = 100; private final int IMG_HEIGTH = 18; private 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 service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setHeader("Pragma","No-cache"); response.setHeader("Cache-Control","no-cache"); response.setDateHeader("Expires", 0); response.setContentType("image/jpeg"); BufferedImage image = new BufferedImage (IMG_WIDTH , IMG_HEIGTH , BufferedImage.TYPE_INT_RGB); Graphics g = image.getGraphics(); Random random = new Random(); g.setColor(getRandColor(200 , 250)); g.fillRect(1, 1, IMG_WIDTH - 1, IMG_HEIGTH - 1); g.setColor(new Color(102 , 102 , 102)); g.drawRect(0, 0, IMG_WIDTH - 1, IMG_HEIGTH - 1); g.setColor(getRandColor(160,200)); for (int i = 0 ; i < 30 ; i++) { int x = random.nextInt(IMG_WIDTH - 1); int y = random.nextInt(IMG_HEIGTH - 1); int xl = random.nextInt(6) + 1; int yl = random.nextInt(12) + 1; g.drawLine(x , y , x + xl , y + yl); } g.setColor(getRandColor(160,200)); for (int i = 0 ; i < 30 ; i++) { int x = random.nextInt(IMG_WIDTH - 1); int y = random.nextInt(IMG_HEIGTH - 1); int xl = random.nextInt(12) + 1; int yl = random.nextInt(6) + 1; g.drawLine(x , y , x - xl , y - yl); } g.setFont(mFont); String sRand = ""; for (int i = 0 ; i < 4 ; i++) { String tmp = getRandomChar(); sRand += tmp; g.setColor(new Color(20 + random.nextInt(110) ,20 + random.nextInt(110) ,20 + random.nextInt(110))); g.drawString(tmp , 15 * i + 10,15); } HttpSession session = request.getSession(true); session.setAttribute("rand" , sRand); // System.out.println("写入session"+sRand); g.dispose(); ImageIO.write(image, "JPEG", response.getOutputStream()); } private String getRandomChar() { int rand = (int)Math.round(Math.random() * 2); long itmp = 0; char ctmp = '\u0000'; switch (rand) { case 1: itmp = Math.round(Math.random() * 25 + 65); ctmp = (char)itmp; return String.valueOf(ctmp); case 2: itmp = Math.round(Math.random() * 25 + 97); ctmp = (char)itmp; return String.valueOf(ctmp); default : itmp = Math.round(Math.random() * 9); return itmp + ""; } } } |
下面是web.xml 配置
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<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"> <display-name>IndustryDemo</display-name> <welcome-file-list> <welcome-file>index.html</welcome-file> <welcome-file>index.htm</welcome-file> <welcome-file>index.jsp</welcome-file> <welcome-file>default.html</welcome-file> <welcome-file>default.htm</welcome-file> <welcome-file>default.jsp</welcome-file> </welcome-file-list> <servlet> <servlet-name>img</servlet-name> <servlet-class>com.zyc.demo.DrewImage</servlet-class> </servlet> <servlet-mapping> <servlet-name>img</servlet-name> <url-pattern>/img.do</url-pattern> </servlet-mapping> </web-app> |
jsp 文件
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<%@ 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 'yanzhengma.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> <body> <img alt="验证码" src="img.do"> <button onclick="window.location.reload();">刷新</button> </body> </html> |
简单实用。
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持服务器之家。
