CheckCode_Servlet.java

package cn.web.response.servlet;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

@WebServlet("/check_code_servlet")
public class CheckCode_Servlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        int width = 100;
        int height = 50;

        //1.创建一对象，在内存中图片(验证码图片对象)
        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);                 //设置画笔颜色
        g.fillRect(0, 0, width, height);

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

        String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghigklmnopqrstuvwxyz0123456789";

        //生成随机角标
        Random ran = new Random();

        for(int i = 1; i <= 4; i++){
            int index = ran.nextInt(str.length());
            //获取字符
            char ch = str.charAt(index);        //随机字符
            //2.3写验证码
            g.drawString(ch + "", width / 5 * i, height / 2);
        }

        //2.4画干扰线
        g.setColor(Color.GREEN);

        //随机生成坐标点
        for(int i = 0; i < 10; i++){
            int x1 = ran.nextInt(width);
            int x2 = ran.nextInt(width);

            int y1 = ran.nextInt(height);
            int y2 = ran.nextInt(height);

            g.drawLine(x1, y1, x2, y2);
        }

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

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doGet(req, resp);
    }
}