1.编写生成英文,数字,汉字随机生成的Servlet类.源代码如下:
[java] view plain copy package com.servlet; import java.awt.*; import java.awt.geom.*; import java.awt.image.*; import java.io.*; import java.util.*; 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 javax.imageio.ImageIO; public class PictureCheckCode extends HttpServlet { private static final long serialVersionUID = 1L; public PictureCheckCode() { super(); } public void destroy() { super.destroy(); } public void init() throws ServletException { super.init(); } /*该方法主要作用是获得随机生成的颜色*/ public Color getRandColor(int s,int e){ Random random=new Random (); if(s>255) s=255; if(e>255) e=255; int r,g,b; r=s+random.nextInt(e-s); //随机生成RGB颜色中的r值 g=s+random.nextInt(e-s); //随机生成RGB颜色中的g值 b=s+random.nextInt(e-s); //随机生成RGB颜色中的b值 return new Color(r,g,b); } @Override public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置不缓存图片 response.setHeader("Pragma", "No-cache"); response.setHeader("Cache-Control", "No-cache"); response.setDateHeader("Expires", 0); //指定生成的响应图片,一定不能缺少这句话,否则错误. response.setContentType("image/jpeg"); int width=86,height=22; //指定生成验证码的宽度和高度 BufferedImage image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB); //创建BufferedImage对象,其作用相当于一图片 Graphics g=image.getGraphics(); //创建Graphics对象,其作用相当于画笔 Graphics2D g2d=(Graphics2D)g; //创建Grapchics2D对象 Random random=new Random(); Font mfont=new Font("楷体",Font.BOLD,16); //定义字体样式 g.setColor(getRandColor(200,250)); g.fillRect(0, 0, width, height); //绘制背景 g.setFont(mfont); //设置字体 g.setColor(getRandColor(180,200)); //绘制100条颜色和位置全部为随机产生的线条,该线条为2f for(int i=0;i<100;i++){ int x=random.nextInt(width-1); int y=random.nextInt(height-1); int x1=random.nextInt(6)+1; int y1=random.nextInt(12)+1; BasicStroke bs=new BasicStroke(2f,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL); //定制线条样式 Line2D line=new Line2D.Double(x,y,x+x1,y+y1); g2d.setStroke(bs); g2d.draw(line); //绘制直线 } //输出由英文，数字，和中文随机组成的验证文字，具体的组合方式根据生成随机数确定。 String sRand=""; String ctmp=""; int itmp=0; //制定输出的验证码为四位 for(int i=0;i<4;i++){ switch(random.nextInt(3)){ case 1: //生成A-Z的字母 itmp=random.nextInt(26)+65; ctmp=String.valueOf((char)itmp); break; case 2: //生成汉字 String[] rBase={"0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f"}; //生成第一位区码 int r1=random.nextInt(3)+11; String str_r1=rBase[r1]; //生成第二位区码 int r2; if(r1==13){ r2=random.nextInt(7); }else{ r2=random.nextInt(16); } String str_r2=rBase[r2]; //生成第一位位码 int r3=random.nextInt(6)+10; String str_r3=rBase[r3]; //生成第二位位码 int r4; if(r3==10){ r4=random.nextInt(15)+1; }else if(r3==15){ r4=random.nextInt(15); }else{ r4=random.nextInt(16); } String str_r4=rBase[r4]; //将生成的机内码转换为汉字 byte[] bytes=new byte[2]; //将生成的区码保存到字节数组的第一个元素中 String str_12=str_r1+str_r2; int tempLow=Integer.parseInt(str_12, 16); bytes[0]=(byte) tempLow; //将生成的位码保存到字节数组的第二个元素中 String str_34=str_r3+str_r4; int tempHigh=Integer.parseInt(str_34, 16); bytes[1]=(byte)tempHigh; ctmp=new String(bytes); break; default: itmp=random.nextInt(10)+48; ctmp=String.valueOf((char)itmp); break; } sRand+=ctmp; Color color=new Color(20+random.nextInt(110),20+random.nextInt(110),random.nextInt(110)); g.setColor(color); //将生成的随机数进行随机缩放并旋转制定角度 PS.建议不要对文字进行缩放与旋转,因为这样图片可能不正常显示 /*将文字旋转制定角度*/ Graphics2D g2d_word=(Graphics2D)g; AffineTransform trans=new AffineTransform(); trans.rotate((45)*3.14/180,15*i+8,7); /*缩放文字*/ float scaleSize=random.nextFloat()+0.8f; if(scaleSize>1f) scaleSize=1f; trans.scale(scaleSize, scaleSize); g2d_word.setTransform(trans); g.drawString(ctmp, 15*i+18, 14); } HttpSession session=request.getSession(true); session.setAttribute("randCheckCode", sRand); g.dispose(); //释放g所占用的系统资源 ImageIO.write(image,"JPEG",response.getOutputStream()); //输出图片 } }
2.配置Servlet
在web.xml中的配置如下：
[java] view plain copy <?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"> <servlet> <description>输出验证码</description> <display-name>This is the display name of my J2EE component</display-name> <servlet-name>PictureCheckCode</servlet-name> <servlet-class><SPAN style="COLOR: #ff0000">com.servlet.PictureCheckCode</SPAN></servlet-class> </servlet> <servlet-mapping> <servlet-name>PictureCheckCode</servlet-name> <url-pattern>/<SPAN style="COLOR: #ff0000">PictureCheckCode</SPAN></url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app> 3.测试验证码可以编写JSP页面来验证是否可以输出验证码图片,JSP代码如下：
1.index.jsp:显示界面
[java] view plain copy <%@ page language="java" import="java.util.*" pageEncoding="gbk"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>验证码</title> <script language="javascript"> function myReload() { document.getElementById("CreateCheckCode").src = document .getElementById("CreateCheckCode").src + "?nocache=" + new Date().getTime(); } </script> </head> <body> <form action="Check.jsp" method="post"> <input name="checkCode" type="text" id="checkCode" title="验证码区分大小写" size="8" ,maxlength="4" /> <img src="PictureCheckCode" id="CreateCheckCode" align="middle"> <a href="" οnclick="myReload()"> 看不清,换一个</a> <input type="submit" value="提交" /> </form> </body> </html>
2.Check.jsp :主要验证提交的数据是否和Session中保存的验证码是否相同
[java] view plain copy <%@ page language="java" import="java.util.*" pageEncoding="gbk"%> <html> <head> <title>验证码校验</title> </head> <body> <% String checkcode=request.getParameter("checkCode"); if(checkcode.equals("")||checkcode==null){ out.print("<script>alert('请输入验证码');window.location.href('index.jsp')</script>"); }else{ if(!checkcode.equalsIgnoreCase((String)session.getAttribute("randCheckCode"))){ out.print("<script>alert('验证码不正确,请重新输入');history.back(-1);</script>"); }else{ out.print("登录成功"); } } %> </body> </html>
4.工程项目结构,及运行截图
