生成验证码的代码

package com.zb.other;

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;

public class makeCertPic {
	

		 //验证码图片中可以出现的字符集，可以根据需要修改
		 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','0','1','2','3',
		   '4','5','6','7','8','9'
		 };
		/* 功能：生成彩色验证码图片
		 参数wedth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
		*/
		 public String getCertPic(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();
		  //设定背景颜色
		  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);
		  //随机产生的验证码
		  String strEnsure = "";
		  //4代表4为验证码，如果要产生更多位的验证码，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验证码，增加drawString语句
		  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15个干扰点
		  Random rand = new Random();
		  for(int i=0; i<10; 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{
		   //输出图形到页面
		   ImageIO.write(image, "JPEG", os);
		   
		  }catch (IOException e){
		   return "";
		  }
		  return strEnsure;
		 }
	

		 

}