验证码下载jsp

时间:2016-07-03 13:56:15
【文件属性】:

文件名称:验证码下载jsp

文件大小:3KB

文件格式:JSP

更新时间:2016-07-03 13:56:15

验证码 生成

<%@ page language="java" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" pageEncoding="utf-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %> <%! public static String code="abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"; Color getRandColor(int fc,int bc){//给定范围获得随机颜色 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); } %> My JSP 'image.jsp' starting page <% //设置页面不缓存 response.setHeader("Pragma","No-cache"); response.setHeader("Cache-Control","no-cache"); response.setDateHeader("Expires", 0); // 在内存中创建图象,设置图片的显示大小 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(); //生成随机类 Random random = new Random(); // 设定背景色 g.setColor(getRandColor(200,250)); g.fillRect(0, 0, width, height); //设定字体 g.setFont(new Font("Times New Roman",Font.PLAIN,18)); //画边框 //g.setColor(new Color()); //g.drawRect(0,0,width-1,height-1); // 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 g.setColor(getRandColor(160,200)); for (int i=0;i<155;i++) { int x = random.nextInt(width); int y = random.nextInt(height); int xl = random.nextInt(12); int yl = random.nextInt(12); g.drawLine(x,y,x+xl,y+yl); } // 取随机产生的认证码(由数字和字母组长的) String sRand=""; for (int i=0;i<4;i++){ int rand=random.nextInt(62); sRand+=String.valueOf(code.charAt(rand)); // 将认证码显示到图象中 g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));// 调用函数出来的颜色相同,可能是因为种子太接近,所以只能直接生成 g.drawString(String.valueOf(code.charAt(rand)),13*i+6,16); } // 将认证码存入SESSION session.setAttribute("rand",sRand); // 图象生效 g.dispose(); // 输出图象到页面 java.io.OutputStream os=response.getOutputStream(); ImageIO.write(image, "JPEG", os); os.flush(); os.close(); os=null; response.flushBuffer(); out.clear(); out = pageContext.pushBody(); %>


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