Java和JavaScript实现验证码的生成和切换验证码

package web.servlet;

import javax.imageio.ImageIO;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

@WebServlet(name = "CheckCodeServlet", value = "/CheckCodeServlet")
public class CheckCodeServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        this.doPost(request,response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        int width = 100;
        int height = 50;

        //1.创建一对象，在内存中的图片（验证码图片象）
        BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);


        //2.美化图片
        //2.1填充背景色
        Graphics g = image.getGraphics();//画笔对象
        g.setColor(Color.PINK);
        g.fillRect(0,0,width,height);

        //2.2画边框
        g.setColor(Color.BLUE);
        g.drawRect(0,0,width - 1, height - 1);


        //2.3写验证码
        String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";//验证码包含的字符
        Random random = new Random();
        for (int i = 1; i <= 4; i++) {
            int index = random.nextInt(str.length());//获取随机数
            char ch = str.charAt(index);//随机字符
            g.drawString(ch + "", width/5*i,height/2);
        }

        //2.4画干扰线
        g.setColor(Color.GREEN);//设置为绿色的干扰线
        for (int i = 0; i < 10; i++) {
            int x1 = random.nextInt(width);
            int x2 = random.nextInt(width);
            int y1 = random.nextInt(height);
            int y2 = random.nextInt(height);
            g.drawLine(x1, y1, x2, y2);

        }


        //3.将图片输出到页面展示
        ImageIO.write(image,"jpg",response.getOutputStream());

    }
}