Struts2自定义结果视图（servlet验证码）

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC
    "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
    "http://struts.apache.org/dtds/struts-2.3.dtd">

<struts>
    <constant name="struts.devMode" value="true" />
    <package name="p1" extends="struts-default">
        <result-types>
            <result-type name="captcha" class="com.itheima.results.CaptchaResult"></result-type>
        </result-types>
        <action name="genCaptcha">
            <result name="success" type="captcha">
                <param name="width">200</param>
                <param name="height">50</param>
            </result>
        </action>
    </package>
</struts>

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;

public class AuthCodeDemo1 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        int width=120,height=25;
        //1.在内存生成一个图片
        BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        //2.得到画笔
        Graphics g = img.getGraphics();
        //3.画一个矩形框
        g.setColor(Color.BLUE);
        g.drawRect(0, 0, width, height);
        //4.填充背景
        g.setColor(Color.YELLOW);
        g.fillRect(1, 1, width-1, height-1);
        //5.画一些干扰线条
        g.setColor(Color.GRAY);
        Random random = new Random();
        for(int i=1;i<=20;i++)
             g.drawLine(random.nextInt(width), random.nextInt(height), random.nextInt(width), random.nextInt(height));
        //6.画字符串随机的
        g.setColor(Color.RED);
        //设置字体
        g.setFont(new Font("宋体",Font.BOLD|Font.ITALIC,20));
        for(int i=1;i<=4;i++)
            g.drawString(random.nextInt(10)+"", i*20,20);
        
        //清除缓存
        response.setHeader("Expires", "-1");
        response.setHeader("Cache-Control", "no-cache");
        response.setHeader("Pragma", "no-cache");
        
        //7.输出
        response.setContentType("image/jpeg");
        ImageIO.write(img, "jpg", response.getOutputStream());
    }

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

}