JSP简单计算验证码生成

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> <%@ page contentType="image/jpeg" import="java.awt.*, java.awt.image.*,javax.imageio.*" %> <% // 在内存中创建图象 int width=60, height=20; BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); // 获取图形上下文 Graphics g = image.getGraphics(); // 设定背景色 g.setColor(new Color(0xDCDCDC)); g.fillRect(0, 0, width, height); //画边框 g.setColor(Color.black); g.drawRect(0,0,width-1,height-1); // 随机产生的认证码(4位数字) String rand =""+ (Math.random()*10000); rand = rand.substring(0,rand.indexOf(".")); switch(rand.length()) { case 1: rand = "000"+rand; break; case 2: rand = "00"+rand; break; case 3: rand = "0"+rand; break; default: rand = rand.substring(0,4); break; } // 将认证码显示到图象中 g.setColor(Color.black); //Integer tempNumber = new Integer(rand); String numberStr = rand;//tempNumber.toString(); g.setFont(new Font("Atlantic Inline",Font.PLAIN,18)); String Str = numberStr.substring(0,1); String num1=Str; g.drawString(Str,8,17); Str = numberStr.substring(2,3); String num22=Str; if(Integer.parseInt(num1)>Integer.parseInt(num22)){ Str ="-"; //numberStr.substring(1,2); }else{ Str ="+"; } g.drawString(Str,20,15); Str = numberStr.substring(2,3); String num2=Str; g.drawString(Str,35,18); Str ="="; //numberStr.substring(3,4); g.drawString(Str,45,15); String total=""; if(Integer.parseInt(num1)>Integer.parseInt(num2)){ total=String.valueOf(Integer.parseInt(num1)-Integer.parseInt(num2)); }else{ total=String.valueOf(Integer.parseInt(num1)+Integer.parseInt(num2)); } // 将认证码存入SESSION session.setAttribute("rand",total); //System.out.println("====>"+rand); // 随机产生88个干扰点，使图象中的认证码不易被其它程序探测到 Random random = new Random(); for (int i=0;i<20;i++) { int x = random.nextInt(width); int y = random.nextInt(height); g.drawOval(x,y,0,0); } // 图象生效 g.dispose(); // 输出图象到页面 ImageIO.write(image, "JPEG", response.getOutputStream()); //在页面上调用 <img src="/Path/checkNum.jsp" mce_src="Path/checkNum.jsp" /> out.clear(); out = pageContext.pushBody(); %>