jsp生成验证码很好的例子

package com.vogoal.util.img; import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.image.BufferedImage; import java.io.IOException; import java.util.Random; import javax.imageio.ImageIO; import javax.servlet.http.HttpServletResponse; /** * @author SinNeR * http://bbs.blueidea.com * image check creater */ public class RandImgCreater { private static final String CODE_LIST = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890"; private HttpServletResponse response = null; private static final int HEIGHT = 20; private static final int FONT_NUM = 4; private int width = 0; private int iNum = 0; private String codeList = ""; private boolean drawBgFlag = false; private int rBg = 0; private int gBg = 0; private int bBg = 0; public RandImgCreater(HttpServletResponse response) { this.response = response; this.width = 13 * FONT_NUM + 12; this.iNum = FONT_NUM; this.codeList = CODE_LIST; } public RandImgCreater(HttpServletResponse response,int iNum,String codeList) { this.response = response; this.width = 13 * iNum + 12; this.iNum = iNum; this.codeList = codeList; } public String createRandImage(){ BufferedImage image = new BufferedImage(width, HEIGHT, BufferedImage.TYPE_INT_RGB); Graphics g = image.getGraphics(); Random random = new Random(); if ( drawBgFlag ){ g.setColor(new Color(rBg,gBg,bBg)); g.fillRect(0, 0, width, HEIGHT); }else{ g.setColor(getRandColor(200, 250)); g.fillRect(0, 0, width, HEIGHT); for (int i = 0; i < 155; i++) { g.setColor(getRandColor(140, 200)); 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); } } g.setFont(new Font("Times New Roman", Font.PLAIN, 18)); String sRand=""; for (int i=0;i<iNum;i++){ int rand=random.nextInt(codeList.length()); String strRand=codeList.substring(rand,rand+1); sRand+=strRand; g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110))); g.drawString(strRand,13*i+6,16); } g.dispose(); try{ ImageIO.write(image, "JPEG", response.getOutputStream()); }catch(IOException e){ } return sRand; } public void setBgColor(int r,int g,int b){ drawBgFlag = true; this.rBg = r; this.gBg = g; this.bBg = b; } 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); } }