Struts2自界说效果视图（servlet验证码）详解编程语言

<?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.获得画笔 
        Graphics g = img.getGraphics(); 
        //3.画一个矩形框 
        g.setColor(Color.BLUE); 
        g.drawRect(0, 0, width, height); 
        //4.填充配景 
        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); 
         
        //消灭缓存 
        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); 
    } 
 
}