基于J2EE Struts框架的课程设计实训项目——《BBS论坛系统》——实现用户身份验证表单中的图形验证码功能

基于J2EE Struts框架的课程设计实训项目——《BBS论坛系统》——实现用户身份验证表单中的图形验证码功能1.1.1实现图形验证码功能1、添加一个实现验证码功能的JavaBean组件类（1）类名称为VerifyCodeBean，包名称为com.px1987.webbbs.util（2）编程该JavaBeanpackage com.px1987.webbbs.util;import java.awt.*;import java.awt.image.BufferedImage;import java.util.*;public class VerifyCodeBean{private Random random ;private int width;private int height;private String VerifyCode = ""; //存储随机产生的认证码(6位数字或者字母) public VerifyCodeBean(){this.width = 90;this.height = 20;random = new Random(); //生成随机类}public int getHeight(){return height;}public void setHeight(int height){this.height = height;}public Random getRandom(){return random;}public void setRandom(Random random){this.random = random;}public String getVerifyCode(){return VerifyCode;}public void setVerifyCode(String verifyCode){VerifyCode = verifyCode;}public int getWidth(){return width;}public void setWidth(int width){this.width = width;}private Color getRandomColor(int foregroundColor,int backgroundColor){ //给定范围获得随机颜色if(foregroundColor > 255){foregroundColor = 255;}if(backgroundColor > 255){backgroundColor = 255;}int r = foregroundColor +random.nextInt(backgroundColor-foregroundColor);int g = foregroundColor +random.nextInt(backgroundColor-foregroundColor);int b = foregroundColor +random.nextInt(backgroundColor-foregroundColor);return new Color(r,g,b);}public BufferedImage getCreateVerifyImage(){//创建一个BufferedImage绘制你的动态图像BufferedImage image =new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);/**创建完一个BufferedImage后，你需要得到图形环境进行绘制，一个Graphics或者Graphics2D对象*/Graphics2D g2d = image.createGraphics();Graphics g = (Graphics)g2d;g.setColor(this.getRandomColor(180, 250));/*生成有6个随机数字和杂乱背景的图片，数字和背景颜色会改变，服务器端刷新（用history.go(-1)也会变）*/g.fillRect(0, 0, width, height);g.setFont(new Font("Times New Roman",Font.PLAIN,18));g.setColor(Color.BLUE);g.drawRect(0,0,width-1,height-1);//画随机线g.setColor(this.getRandomColor(160,200));/*随机产生155条干扰线，使图象中的认证码不易被其它程序探测到*/for(int i = 0 ; i < 150 ; i++){int x = random.nextInt(width);int y = random.nextInt(height);int x1 = random.nextInt(12);int y1 = random.nextInt(12);g.drawLine(x, y, x+x1, y+y1);}for(int i = 0 ; i < 6 ; i++){String[] str = { "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v","w", "x", "y", "z", "A", "B", "C", "D", "E", "F", "G", "H","I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T","U", "V", "W", "X", "Y", "Z","1","2","3","4","5","6","7","8","9" };String randomStr = str[random.nextInt(str.length-1)];//String randomStr = String.valueOf(random.nextInt(10));VerifyCode+=randomStr; // 取随机产生的认证码(4位数字)g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));/*将认证码显示到图象中*/g.drawString(randomStr,13*i+6,16);}/*上面为绘制图像内容，对图形环境绘制就会画到BufferedImage。

最开始这个图像都是黑色的，因此用你希望的背景颜色填充图像是一个不错的主意，然后，当你完成图像的绘制，你需要dispose图形环境*/g.dispose();return image;}}2、再添加一个在页面中产生验证码JPEG图像功能的调度Servlet组件（1）新建一个Servlet组件（2）类名称为ShowVerifyCodeImage，包名称为com.px1987.webbbs.servlet（3）设置该Servlet的url-pattern为：/showVerifyCodeImage（4）将产生出下面的Servlet组件（5）编程该Servlet组件package com.px1987.webbbs.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;import com.px1987.webbbs.util.VerifyCodeBean; public class ShowVerifyCodeImage extends HttpServlet{ public ShowVerifyCodeImage(){super();}public void destroy() {super.destroy();}public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {VerifyCodeBean verifyCodeBeanID=new VerifyCodeBean();java.awt.image.BufferedImage image=verifyCodeBeanID.getCreateVerifyImage();HttpSession session=request.getSession();String verifyCodeInSession=verifyCodeBeanID.getVerifyCode();session.setAttribute("verifyCode",verifyCodeInSession); // 将认证码存入SESSION/*一旦完成图像的绘制，你在response中返回那个图像。