java验证码生成

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<head><script type="text/javascript">// 更换验证码function reloadcode() {var verify = document.getElementById("code");verify.setAttribute("src", "makeCertPic.jsp?it=" + Math.random());}</script></head><body><img src="makeCertPic.jsp" id="code" onclick="reloadcode()"></img><ahref="#" onclick="reloadcode()">换一张</a></body>

makeCerPic.jsp

<%@page contentType="image/jpeg"%><jsp:useBean id="image" scope="page"class="com.util.MakeCertPicUtil" /><%// 验证码生成String str = image.getCertPic(70, 26, response.getOutputStream());// 将认证码存入sessionsession.setAttribute("certCode", str);out.clear();out = pageContext.pushBody();%>

MakeCertPicUtil.java

package com.util;import java.awt.Color;import java.awt.Font;import java.awt.Graphics;import java.awt.image.BufferedImage;import java.io.IOException;import java.io.OutputStream;import java.util.Random;import javax.imageio.ImageIO;/** *  * 验证码生成 *  *  */public class MakeCertPicUtil {/** * 验证码图片中可以出现的字符集 */private char mapTable[] = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I','J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V','W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i','j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v','w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8','9' };/** * 给定范围获得随机颜色 *  * @param fc * @param bc * @return */private Color getRandColor(int fc, int bc) {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);}/** * 生成彩色验证码图片参数width为生成图片的宽度,参数height为生成图片的高度,参数os为页面的输出流 *  * @param width * @param height * @param os * @return */public String getCertPic(int width, int height, OutputStream os) {if (width <= 0)width = 70;if (height <= 0)height = 22;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(getRandColor(200, 250));g.fillRect(0, 0, width, height);// 画边框g.setColor(getRandColor(160, 200));g.drawRect(0, 0, width - 1, height - 1);// 取随机产生的认证码String strEnsure = "";// 4代表4位验证码,如果要生成更多位的认证码,则加大数值for (int i = 0; i < 4; ++i) {strEnsure += mapTable[(int) (mapTable.length * Math.random())];}// 将认证码显示到图像中,如果要生成更多位的认证码,增加drawString语句g.setColor(getRandColor(160, 200));g.setFont(new Font("Atlantic Inline", Font.PLAIN, 18));String str = strEnsure.substring(0, 1);g.drawString(str, 8, 17);str = strEnsure.substring(1, 2);g.drawString(str, 20, 15);str = strEnsure.substring(2, 3);g.drawString(str, 35, 18);str = strEnsure.substring(3, 4);g.drawString(str, 45, 15);// 随机产生100个干扰点Random rand = new Random();for (int i = 0; i < 100; i++) {int x = rand.nextInt(width);int y = rand.nextInt(height);g.drawOval(x, y, 1, 1);}// 释放图形上下文g.dispose();try {// 输出图像到页面ImageIO.write(image, "JPEG", os);} catch (IOException e) {return "";}return strEnsure;}}