Servlet实现随机验证码
2007-04-25 18:08
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写servlet
package com.jvcn.inc; import java.io.*; import java.util.*; import com.sun.image.codec.jpeg.*; import javax.servlet.*; import javax.servlet.http.*; import java.awt.*; import java.awt.image.*; public class VerifyCode extends HttpServlet { private Font mFont = new Font("Times New Roman", Font.PLAIN, 18); //设置字体 //处理post public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //取得一个1000-9999的随机数 HttpSession session = request.getSession(ture); response.setContentType("image/gif"); response.setHeader("Pragma", "No-cache"); response.setHeader("Cache-Control", "no-cache"); response.setDateHeader("Expires", 0); int width = 60, height = 20; ServletOutputStream out = response.getOutputStream(); BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); //设置图片大小的 Graphics gra = image.getGraphics(); Random random = new Random(); gra.setColor(getRandColor(200, 250)); //设置背景色 gra.fillRect(0, 0, width, height); gra.setColor(Color.black); //设置字体色 gra.setFont(mFont); /* gra.setColor(new Color(0)); gra.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 gra.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); gra.drawLine(x, y, x + xl, y + yl); } // 取随机产生的认证码(4位数字) String sRand = ""; for (int i = 0; i < 4; i++) { String rand = String.valueOf(random.nextInt(10)); sRand += rand; // 将认证码显示到图象中 gra.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 gra.drawString(rand, 13 * i + 6, 16); } session.setAttribute("verify",sRand ); //System.out.println("showimage="+sRand); // session.setAttribute("getImg", sRand); JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out); encoder.encode(image); out.close(); } static 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); } } |
写入后在web.xml中添加:
<servlet> <servlet-name>verifycode</servlet-name> <servlet-class>com.jvcn.inc.VerifyCode</servlet-class> </servlet> <servlet-mapping> <servlet-name>verifycode</servlet-name> <url-pattern>/verifycode</url-pattern> </servlet-mapping> |
在html代码里加入:
<img src="/verifycode" />
验证的时候取SESSION里的属性跟录入的比较,就这简单
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