day84 json中实现简单验证码

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项目中的问题:
        1 修改JS或CSS后,页面不能及时更新?
                把浏览器-->"开发者工具"-->"网络"-->选中"禁用缓存"
        2 如何把HTML页面转为JSP页面
 将jsp页面中的<%@ page contentType="text/html;charset=UTF-8" language="java" %>指令复制到html文件头

3 如何实现简单验证码操作:  

          生成验证码的RandomCodeController类

package com.xja.controller; /*** @author 赵淑娜* Date  2024/4/26 10:15*/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 = "randomCode.do", value = "/RandomCodeController")
public class RandomCodeController extends HttpServlet {private static final String CONTENT_TYPE = "image/jpeg";//Initialize global variablespublic void init() throws ServletException {}//产生随机颜色函数getRandColorColor getRandColor(int fc, int bc) {Random r = new Random();if (fc > 255) fc = 255;if (bc > 255) bc = 255;int red = fc + r.nextInt(bc - fc); //红int green = fc + r.nextInt(bc - fc); //绿int blue = fc + r.nextInt(bc - fc); //蓝return new Color(red, green, blue);}//Process the HTTP Get requestpublic void doGet(HttpServletRequest request, HttpServletResponse response) throwsServletException, IOException {response.setContentType(CONTENT_TYPE);HttpSession session = request.getSession();//设置页面不缓存response.setHeader("Pragma", "No-cache");response.setHeader("Cache-Control", "no-cache");response.setDateHeader("Expires", 0);//创建随机类Random r = new Random();// 在内存中创建图像，宽度为width，高度为heightint width = 60, height = 20;BufferedImage pic = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);// 获取图形上下文环境Graphics gc = pic.getGraphics();// 设定背景色并进行填充gc.setColor(getRandColor(200, 250));gc.fillRect(0, 0, width, height);//设定图形上下文环境字体gc.setFont(new Font("Times New Roman", Font.PLAIN, 20));// 随机产生200条干扰直线，使图像中的认证码不易被其他分析程序探测到for (int i = 0; i < 200; i++) {int x1 = r.nextInt(width);int y1 = r.nextInt(height);int x2 = r.nextInt(15);int y2 = r.nextInt(15);gc.setColor(getRandColor(160, 200));gc.drawLine(x1, y1, x1 + x2, y1 + y2);}//随机产生100个干扰点，使图像中的验证码不易被其他分析程序探测到for (int i = 0; i < 100; i++) {int x = r.nextInt(width);int y = r.nextInt(height);gc.setColor(getRandColor(120, 240));gc.drawOval(x, y, 0, 0);}// 随机产生4位数字的验证码String RS = "";String rn = "";RS = r.nextInt(9000) + 1000 + "";/*for(int i=0;i<4;i++){//产生10以内随机数字rnrn=String.valueOf(r.nextInt(10));RS+=rn;//将认证码用drawString函数显示到图像里gc.setColor(new Color(20+r.nextInt(110),20+r.nextInt(110),20+r.nextInt(110)));gc.drawString(rn,13*i+6,16);}*/gc.setColor(new Color(20 + r.nextInt(110), 20 + r.nextInt(110),20 + r.nextInt(110)));gc.drawString(RS, 10, 16);// 释放图形上下文环境gc.dispose();// 将认证码RS存入SESSION中共享session.setAttribute("random", RS);// 输出生成后的验证码图像到页面ImageIO.write(pic, "JPEG", response.getOutputStream());}//Process the HTTP Post requestpublic void doPost(HttpServletRequest request, HttpServletResponse response) throwsServletException, IOException {doGet(request, response);}//Clean up resourcespublic void destroy() {}
}

        显示生成的验证码：

                <img src="${pageContext.request.contextPath}/RandomCodeController" />

      

         生成的验证码在session对象中存储:

                  session.setAttribute("random", RS) ;       
         

         "看不清",点击事件相关操作： 重新给图片设置src属性值:
               

      $("#codeImg").attr("src",$("#path").val()+"/RandomCodeController?t="+Math.random())

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