jsp生成验证码

jsp生成验证码

作者:guang520; 来源:http://www.javaresearch.org/article/182367.htm

<%@ page contentType="image/jpeg" import="java.awt.*, java.awt.image.*,java.util.*,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); // 取随机产生的认证码(4位数字) String rand = request.getParameter("rand"); 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; } // 将认证码存入SESSION session.setAttribute("rand",rand); // 将认证码显示到图象中 g.setColor(Color.black); Integer tempNumber = new Integer(rand); String numberStr = tempNumber.toString(); g.setFont(new Font("Atlantic Inline",Font.PLAIN,18)); String Str = numberStr.substring(0,1); g.drawString(Str,8,17); Str = numberStr.substring(1,2); g.drawString(Str,20,15); Str = numberStr.substring(2,3); g.drawString(Str,35,18); Str = numberStr.substring(3,4); g.drawString(Str,45,15); // 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()); %>