java验证码

package xf.web;

import java.awt.*;
import java.awt.geom.*;
import java.awt.image.*;
import java.io.*;
import java.util.*;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import javax.imageio.ImageIO;

public class DrawImage extends HttpServlet {

    private static final long serialVersionUID = 1L;

    public DrawImage() {
        super();
    }

    public void destroy() {
        super.destroy();
    }

    public void init() throws ServletException {
        super.init();
    }
    /*该方法主要作用是获得随机生成的颜色*/
    public Color getRandColor(int s,int e){
        Random random=new Random ();
        if(s>255) s=255;
        if(e>255) e=255;
        int r,g,b;
        r=s+random.nextInt(e-s);	//随机生成RGB颜色中的r值
        g=s+random.nextInt(e-s);	//随机生成RGB颜色中的g值
        b=s+random.nextInt(e-s);	//随机生成RGB颜色中的b值
        return new Color(r,g,b);
    }

    @Override
    public void service(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //设置不缓存图片
        response.setHeader("Pragma", "No-cache");
        response.setHeader("Cache-Control", "No-cache");
        response.setDateHeader("Expires", 0);
        //指定生成的响应图片,一定不能缺少这句话,否则错误.
        response.setContentType("image/jpeg");
        int width=86,height=25;		//指定生成验证码的宽度和高度
        BufferedImage image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);	//创建BufferedImage对象,其作用相当于一图片
        Graphics g=image.getGraphics();		//创建Graphics对象,其作用相当于画笔
        Graphics2D g2d=(Graphics2D)g;		//创建Grapchics2D对象
        Random random=new Random();
        Font mfont=new Font("console",Font.BOLD,16);	//定义字体样式
        g.setColor(getRandColor(200,250));
        g.fillRect(0, 0, width, height);	//绘制背景
        g.setFont(mfont);					//设置字体
        g.setColor(getRandColor(180,200));

        //绘制100条颜色和位置所有为随机产生的线条,该线条为2f
        for(int i=0;i<100;i++){
            int x=random.nextInt(width-1);
            int y=random.nextInt(height-1);
            int x1=random.nextInt(6)+1;
            int y1=random.nextInt(12)+1;
            BasicStroke bs=new BasicStroke(2f,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);	//定制线条样式
            Line2D line=new Line2D.Double(x,y,x+x1,y+y1);
            g2d.setStroke(bs);
            g2d.draw(line);		//绘制直线
        }
        //输出由英文，数字 随机组成的验证码。

        String sRand="";
        String ctmp="";
        int itmp=0;
        //制定输出的验证码为四位
        for(int i=0;i<4;i++){
            switch(random.nextInt(2)){
                case 0:		//生成A-Z的字母
                    itmp=random.nextInt(26)+65;
                    ctmp=String.valueOf((char)itmp);
                    break;
                default:		//0-9
                    String[] rBase={"0","1","2","3","4","5","6","7","8","9"};
                    int x = random.nextInt(10);
                    ctmp = rBase[x];
                    break;
            }
            sRand+=ctmp;
            Color color=new Color(20+random.nextInt(110),20+random.nextInt(110),random.nextInt(110));
            g.setColor(color);
            //将生成的随机数进行随机缩放并旋转制定角度 PS.建议不要对文字进行缩放与旋转,由于这样图片可能不正常显示
			/*将文字旋转制定角度*/
            Graphics2D g2d_word=(Graphics2D)g;
            AffineTransform trans=new AffineTransform();
            trans.rotate((45) * 3.14 / 180, 15 * i + 8, 7);

            g2d_word.setTransform(trans);
            g.drawString(ctmp, 15*i+18, 14);
        }
        HttpSession session=request.getSession(true);
        session.setAttribute("randCheckCode", sRand);//设置一个变量的值，你以后可用getAttribute()来获取和使用它
        g.dispose();	//释放g所占用的系统资源
        ImageIO.write(image,"jpeg",response.getOutputStream());	//输出图片
    }
}