前台jsp页面与servlet传输图片验证码

效果图

<%@page import="java.util.*"%>
<%@ 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>
<style type="text/css">
#acc {
   width: 40px
}
</style>
<script type="text/javascript">
   function change(){
       var yzm = document.getElementById("yzm");
       yzm.src = "GetImgServlet?a="+new Date().getTime();
   }
</script>
</head>
<body>
   <form action="login.action">
       account:<input type="text"><br> password:<input
           type="password"><br> messyzm：<input type="text" id="acc"
           name="qtyzm"> <img title="点击换图" id="yzm" src="GetImgServlet"onclick="change()">
           看不清
           <br>
           <input type="submit"
           value="submit">
   </form>
</body>
</html>

验证码类

package cn.itcast.vcode.utils;

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;

import javax.imageio.ImageIO;

public class VerifyCode {
   private int w = 70;
   private int h = 35;
    private Random r = new Random();
    // {"宋体", "华文楷体", "黑体", "华文新魏", "华文隶书", "微软雅黑", "楷体_GB2312"}
   private String[] fontNames = {"宋体", "华文楷体", "黑体", "微软雅黑", "楷体_GB2312"};
   private String codes = "23456789abcdefghjkmnopqrstuvwxyzABCDEFGHJKMNPQRSTUVWXYZ";
   private Color bgColor = new Color(255, 255, 255);
   private String text ;

   private Color randomColor () {
       int red = r.nextInt(150);
       int green = r.nextInt(150);
       int blue = r.nextInt(150);
       return new Color(red, green, blue);
   }

   private Font randomFont () {
       int index = r.nextInt(fontNames.length);
       String fontName = fontNames[index];
       int style = r.nextInt(4);
       int size = r.nextInt(5) + 24;
       return new Font(fontName, style, size);
   }

   private void drawLine (BufferedImage image) {
       int num = 3;
       Graphics2D g2 = (Graphics2D)image.getGraphics();
       for(int i = 0; i < num; i++) {
           int x1 = r.nextInt(w);
           int y1 = r.nextInt(h);
           int x2 = r.nextInt(w);
           int y2 = r.nextInt(h);
           g2.setStroke(new BasicStroke(1.5F));
           g2.setColor(Color.BLUE);
           g2.drawLine(x1, y1, x2, y2);
       }
   }

   private char randomChar () {
       int index = r.nextInt(codes.length());
       return codes.charAt(index);
   }

   private BufferedImage createImage () {
       BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
       Graphics2D g2 = (Graphics2D)image.getGraphics();
       g2.setColor(this.bgColor);
       g2.fillRect(0, 0, w, h);
        return image;
   }

   public BufferedImage getImage () {
       BufferedImage image = createImage();
       Graphics2D g2 = (Graphics2D)image.getGraphics();
       StringBuilder sb = new StringBuilder();
       // 向图片中画4个字符
       for(int i = 0; i < 4; i++) {
           String s = randomChar() + "";
           sb.append(s);
           float x = i * 1.0F * w / 4;
           g2.setFont(randomFont());
           g2.setColor(randomColor());
           g2.drawString(s, x, h-5);
       }
       this.text = sb.toString();
       drawLine(image);
       return image;
   }

   public String getText () {
       return text;
   }

   public static void output (BufferedImage image, OutputStream out)
               throws IOException {
       ImageIO.write(image, "JPEG", out);
   }
}

package com.zhang.test;

import java.awt.image.BufferedImage;
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;

import cn.itcast.vcode.utils.VerifyCode;

/**
* Servlet implementation class GetImgServlet
*/
@WebServlet(urlPatterns= {"/GetImgServlet","/login.action"})
public class GetImgServlet extends HttpServlet {
   private static final long serialVersionUID = 1L;
public GetImgServlet() {
super();

}
   protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       String type=request.getRequestURI();
       if(type.endsWith("GetImgServlet")) {
           VerifyCode vc = new VerifyCode();
                       BufferedImage bi = vc.getImage();
                       request.getSession().setAttribute("yzm", vc.getText());
                       vc.output(bi, response.getOutputStream());
       }else {
           String mess=request.getSession().getAttribute("yzm").toString().toLowerCase();
           String qtyzm=request.getParameter("qtyzm").toLowerCase();
           System.out.println(mess+"***"+qtyzm);
           if(mess.equals(qtyzm)) {
               response.getWriter().write("successLogin");
           }else {
               response.getWriter().write("failLogin");
           }

       }

   }
   protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

       doGet(request, response);
   }

}
因为浏览器缓存问题所以点击更换验证码要加new Date().getTime();

并导入java包

前台jsp页面与servlet传输图片验证码

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