Ajax验证验证码是否正确

╰+哭是因爲堅強的太久メ 2022-01-23 07:35 310阅读 0赞

一、前端登录界面jsp：

很简单，就一个文本框和一个图片标签：

<%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
    <!DOCTYPE html>
    <html>
    <head>
    <meta charset="UTF-8">
    <title>Insert title here</title>
    </head>
    <body>
      验证码：<input id="yzm" name="code" type="text" />
      <img src="ImageServlet">
    </body>
    </html>

二、图片服务器（我们把验证码放入到了session中，便于下一步的判断）：

package cn.skh.servlet;
    
    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.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    /**
     * Servlet implementation class ImageServlet
     */
    @WebServlet("/ImageServlet")
    public class ImageServlet extends HttpServlet {
    	private static final long serialVersionUID = 1L;
           
        /**
         * @see HttpServlet#HttpServlet()
         */
        public ImageServlet() {
            super();
            // TODO Auto-generated constructor stub
        }
    
    	/**
    	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
    	 */
    	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    
    		response.setHeader("Expires", "-1");
    		response.setHeader("Cache-Control", "no-cache");
    		response.setHeader("Pragma", "no-cache");
    		
    
    		int width = 120;
    		int height = 25;
    		//创建一副内存图像：BufferedImage
    		BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
    		//得到属于该图片的画笔：Graphics
    		Graphics g = image.getGraphics();
    			//画边框
    		g.setColor(Color.BLUE);
    		g.drawRect(0, 0, width, height);
    			//填充背景色
    		g.setColor(Color.YELLOW);
    		g.fillRect(1, 1, width-2, height-2);
    			//画干扰线
    		g.setColor(Color.GRAY);
    		
    		Random r = new Random();
    		for(int i=0;i<10;i++)
    			g.drawLine(r.nextInt(width), r.nextInt(height), r.nextInt(width), r.nextInt(height));
    		
    			//随机数字
    		g.setColor(Color.RED);
    		g.setFont(new Font("宋体", Font.BOLD|Font.ITALIC, 20));
    		int x = 23;
    		StringBuffer sb = new StringBuffer();
    		for(int i=0;i<4;i++){
    			String code = r.nextInt(10)+"";
    			sb.append(code);
    			
    			g.drawString(code, x, 20);
    			x+=20;
    		}
    		System.out.println(sb.toString());
    		//把验证码放到HttpSession中
    		request.getSession().setAttribute("code", sb.toString());
    		//输出到浏览器的页面上:ImageIO
    		ImageIO.write(image, "jpg", response.getOutputStream());
    	}
    
    	/**
    	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
    	 */
    	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		// TODO Auto-generated method stub
    		doGet(request, response);
    	}
    
    }

三、Ajax，在这里我是用的是post方法：给文本框添加了一个失去焦点的事件

四、验证Servlet：

package cn.skh.servlet;
    
    import java.io.IOException;
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    /**
     * Servlet implementation class DoImg
     */
    @WebServlet("/DoImg")
    public class DoImg extends HttpServlet {
    	private static final long serialVersionUID = 1L;
           
        /**
         * @see HttpServlet#HttpServlet()
         */
        public DoImg() {
            super();
            // TODO Auto-generated constructor stub
        }
    
    	/**
    	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
    	 */
    	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		String code1 = request.getParameter("code");
    		String code = (String) (request.getSession().getAttribute("code"));
    		if(code1.equals(code)){
    			response.getWriter().print("true");
    		}else {
    			response.getWriter().print("false");
    		}
    	}
    
    	/**
    	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
    	 */
    	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		// TODO Auto-generated method stub
    		doGet(request, response);
    	}
    
    }

功能效果：r如果输入验证码正确会弹出Success的窗口，否则会弹出Default的窗口