动态验证码 关键代码

af8991

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;/** * 动态验证码 关键代码 * @author xiaer * */public class ImageEnsure {public ImageEnsure() {}private char mapTable[]={  'A','B','C','D','E','F',  'G','H','I','J','K','L',  'M','N','P','Q','R',  'S','T','U','V','W','X',  'Y','Z','0','1','2','3',  '4','5','6','7','8','9'};public String getEnsure(int width, int height, OutputStream os) {if(width<=0)width=60;if(height<=0)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(0xFCF000));   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  String strEnsure = "";  // 4代表4位验证码  for(int i=0; i<4; ++i) {   strEnsure += mapTable[(int)(mapTable.length*Math.random())];  }    // 将认证码显示到图象中   g.setColor(Color.black);   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50个干扰点  Random rand = new Random();  for (int i=0;i<50;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 {// 输出图象到页面 ImageIO.write(image, "JPEG", os);} catch (IOException e) {return "";}finally{}return strEnsure;}/*public static void main(String []args) {try{BufferedOutputStream os = new BufferedOutputStream(new FileOutputStream("c:\\test.jpg"));       new ImageEnsure().getEnsure(100, 200, os);os.flush();os.close();} catch(Exception e) {}}*/}