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session实现带随机验证码的登陆

2016-09-10 10:23 369 查看

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>登陆页面</title>

<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="this is my page">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">

</head>

<body>

<form action="/Session/servlet/LoginServlet2" method="post">
用户名：<input type="text" name="username"><br/>
密码：<input type="password" name="password"><br/>
认证码：<input type="text" name="checkcode"><img src="/Session/servlet/ImageServlet"><br/>

<input type="submit" value="登陆">
</form>

</body>
</html>

package login2;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LoginServlet2 extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

String checkcode = request.getParameter("checkcode");
String s_checkcode = (String) request.getSession().getAttribute("checkcode");
if(checkcode==null || s_checkcode==null || !checkcode.equals(s_checkcode)){
System.out.println("认证码错误！！");
return;
}

//得到用户名和密码，帮用户完成登陆

}

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

doGet(request, response);
}

}

package login2;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
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;

//输出随机图片
public class ImageServlet extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

//6.设置头，控制浏览器不要缓存图片数据

response.setHeader("Expires", "-1");
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Pragma", "no-cache");

//5.通知浏览器以图片方式打开
response.setHeader("Content-type", "image/jpeg");

//1.在内存中创建一副图片
BufferedImage image = new BufferedImage(80,20,BufferedImage.TYPE_INT_RGB);

//2.得到图片
Graphics2D  g = (Graphics2D) image.getGraphics();
//设置图片背景色
g.setColor(Color.WHITE);
g.fillRect(0, 0, 80, 20);

//3.向图片上写数据
g.setColor(Color.BLUE);
g.setFont(new Font(null,Font.BOLD,20));
String checkcode = makeNum();
request.getSession().setAttribute("checkcode", checkcode);
g.drawString(checkcode, 0, 20);

//4.将图片写给浏览器
ImageIO.write(image, "jpg", response.getOutputStream());

}

private String makeNum() {

Random r = new Random();
String num = r.nextInt(9999999) + "";  //0-9999999  123  1234567
StringBuffer sb = new StringBuffer();
for(int i=0;i<7-num.length();i++){
sb.append("0");
}

num = sb.toString()+num;

return num;
}

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

doGet(request, response);
}

}

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标签： session 验证码

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