servlet2.java

宠物医院 JSP项目 我是一个初学者 请大家多多指教

package servlet;

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

public class Servlet2 extends HttpServlet {
    public void destroy() {
        super.destroy();
    }

    public void doGet(HttpServletRequest request, HttpServletResponse response) throws
            ServletException, IOException {
        response.setContentType("text/html; charset=UTF-8");
        getImage(request, response);
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response) throws
            ServletException, IOException {
        doGet(request, response);
    }

    public void init() throws ServletException {

    }

    //给定范围获得随机颜色
    public 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);
    }

    //产生验证码图片
    public void getImage(HttpServletRequest request,
                         HttpServletResponse response) throws
            ServletException, IOException {
        // 在内存中创建图象
        int width = 60, height = 20;
        BufferedImage image = new BufferedImage(width, height,
                                                BufferedImage.TYPE_INT_RGB);
        // 获取图形上下文
        Graphics g = image.getGraphics();
        //生成随机类
        Random random = new Random();
        // 设定背景色
        g.setColor(getRandColor(200, 250));
        g.fillRect(0, 0, width, height);
        //设定字体
        g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
        //画边框
        g.setColor(getRandColor(100, 250));
        g.drawRect(0, 0, width - 1, height - 1);
        // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
        g.setColor(getRandColor(160, 230));
        for (int i = 0; i < 155; i++) {
            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);
        }
        //设置随机出现的字符
        String str =
                "abcdefghigklmnopqrstuvtxyzABCDEFGHIGKLMNOPQRSTUVWXYZ0123456789";
        //声明一个字符串sRand用来存放产生的验证码
        String sRand = "";
        // 取随机产生的验证码(4位)
        for (int i = 0; i < 4; i++) {
            String rand = String.valueOf(str.charAt(random.nextInt(62)));
            sRand += rand;
            // 将验证码显示到图象中
            g.setColor(new Color(20 + random.nextInt(110),
                                 20 + random.nextInt(110),
                                 20 + random.nextInt(110)));
            //如果调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
            g.drawString(rand, 13 * i + 6, 16);
        }
        // 图象生效
        g.dispose();
        //把产生的验证码存在Session中,用来验证用户输入的验证码是否正确
        HttpSession session = request.getSession(true);
        session.setAttribute("rand", sRand);
        // 输出图象到页面
        ImageIO.write(image, "JPEG", response.getOutputStream());
    }
}