java验证码

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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条颜色和位置全部为随机产生的线条,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,因为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    }}
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