java验证码

package com.hwq.regist.servlet;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
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;

/**
* @Author: bruce
* @Description:com.hwq.regist.servlet
* @Date: Created in 23:29 2018/7/9
* @Modifiy By:
*/
public class codeServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 使用java图形界面技术绘制一张图片

    int charNum = 4;
    int width = 20 * 4;
    int height = 28;

    // 1. 创建一张内存图片
    BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB );/*第三个是颜色*/

    // 2.获得绘图对象
    Graphics graphics = bufferedImage.getGraphics();

    // 3、绘制背景颜色
    graphics.setColor(Color.YELLOW);
    graphics.fillRect(0, 0, width, height);

    // 4、绘制图片边框
    graphics.setColor(Color.GRAY);
    graphics.drawRect(0, 0, width - 1, height - 1);

    // 5、输出验证码内容
    graphics.setColor(Color.RED);
    graphics.setFont(new Font("宋体", Font.BOLD, 22));

    // 随机输出4个字符
    String s = "ABCDEFGHGKLMNPQRSTUVWXYZ23456789";
    Random random = new Random();

    // session中要用到
    String msg = "";

    int x = 5;
    for (int i = 0; i < charNum; i++) {
        int index = random.nextInt(32);
        String content = String.valueOf(s.charAt(index));

        msg += content;
        graphics.setColor(new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255)));
        graphics.drawString(content, x, 22);
        x += 20;
    }
    request.getSession().setAttribute("code",msg);

    // 6、绘制干扰线
    graphics.setColor(Color.GRAY);
    for (int i = 0; i < 5; i++) {
        int x1 = random.nextInt(width);
        int x2 = random.nextInt(width);

        int y1 = random.nextInt(height);
        int y2 = random.nextInt(height);
        graphics.drawLine(x1, y1, x2, y2);
    }

    // 释放资源
    graphics.dispose();

    // 图片输出 ImageIO
    ImageIO.write(bufferedImage, "jpg", response.getOutputStream());

}


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

}