(1)生成验证码的servlet:
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;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
public class YzmServlet extends HttpServlet {
//设置验证码图片的宽度
private static final int WIDTH = 100;
//设置验证码的高度
private static final int HEIGHT = 80;
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { ???????????????????//产生一张图片 ???????BufferedImage image=new BufferedImage(Width,Height,BufferedImage.TYPE_INT_RGB); ???response.setHeader("Pragram","no-cache"); ???response.setHeader("Cache-Control","no-catch"); ???response.setDateHeader("Exprires",0); ???Graphics g=image.getGraphics(); ???????????//设置背景颜色 ???g.setColor(Color.WHITE); ???????????//填充图片 ???g.fillRect(0,0,Width,Height); ???????????//设置验证码颜色 ???g.setColor(Color.RED); ???????????//设置验证码字体及大小 ???Font font=new Font("微软雅黑",Font.BOLD,20); ???????????//获取验证码 ???String str=getRandomString(4); ???????????//获取session ??HttpSession session=request.getSession(); ????????//给str做标记 ??session.setAttribute("str",str); ????????//在图片中画出验证码 ???g.drawString(str,50,50); ???????????//在图片中随机划线 ???for (int i=0;i<15;i++){ ???????int x1= RandomUtils.nextInt(0,Width); ???????int x2=RandomUtils.nextInt(0,Width); ???????int y1=RandomUtils.nextInt(0,Height); ???????int y2=RandomUtils.nextInt(0,Height); ???????????????????????????Color color=new Color(RandomUtils.nextInt(0,255),RandomUtils.nextInt(0,255),RandomUtils.nextInt(0,255)); ???????g.setColor(color); ???????g.drawLine(x1,y1,x2,y2); ???} ???????????//输出图片 ???ImageIO.write(image,"jpg",response.getOutputStream());}}
(2)登陆验证的servlet:
import org.apache.commons.lang3.RandomUtils;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
public class LoginServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { ???doGet(request, response);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { ???response.setCharacterEncoding("utf-8"); ???response.setContentType("text/html;charset=utf-8"); ???request.setCharacterEncoding("utf-8"); ???????????//获取输入的验证码的值 ???String yzm=request.getParameter("yzm"); ???????????//获取输入的用户名 ???String username=request.getParameter("username"); ???????????//获取输入的密码 ???String userpassword=request.getParameter("userpassword"); ???????????//获取session ???HttpSession session=request.getSession(); ???????????//获取session标记的值,即服务端生成的验证码的值 ???String yzm2=(String) session.getAttribute("str"); ??//比较验证码 ????????if (yzm.equals(yzm2)){ ??????if(username.equals("zhangsan")&&userpassword.equals("123456")){ ??????????response.getWriter().print("登陆成功"); ??????}else{ ??????????response.getWriter().print("用户名或密码错误"); ??????} ???}else{ ???????response.getWriter().print("验证码错误"); ???}}}
(3)登陆界面(比较简陋)
<html lang="en">
<head>
<meta charset="UTF-8">
<title>登陆</title>
</head>
<script type="text/javascript">
function refreshImg() {
document.getElementById("y").src="./Yzm";
}
</script>
<body>
<table width="760px" height="100%" align="center" style="background-color: azure">
<tr>
<td>
<div align="center"></div>
<table width="200" height="300">
<tr>
<td>
<form action="./Login" name="form1" method="post">
用户名:<input type="text" name="username">
密 码:<input type="password" name="userpassword">
<a>
<img id="y" name="y" src="./Yzm" height="100" onclick="refreshImg()">
</a>
<button type="submit" value="看不清?" style="background-color: red" onclick="refreshImg()">看不清?</button><br>
验证码:<input type="text" name="yzm" id="yzm" style="width: 30px" onclick="refreshImg()"><br>
????????????????????<button type="submit" onclick="check()">提交</button> ????????????????????<button type="reset">重置</button> ????????????????</form> ????????????</td> ????????</tr> ???????</table> ???????</div> ???</td></tr></table>
</body>
</html>
(4)配置web.xml
<?xml version="1.0" encoding="utf-8"?>
网页登陆注册(jsp实现)验证码
原文地址：http://blog.51cto.com/13670525/2149116