带有验证码&session&退出的登录验证

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带有验证码&session&退出的登录验证
需求：
1-1.登录时验证验证码（数字和字母的组合，不区分大小写）
1-2：验证码可以点击刷新。
2.验证用户名，密码。
3.登录后不关闭浏览器的条件下可以免输入账号密码登录。
4,登录后可以点击退出，退出登陆。

思路：1.验证码：使用VerifyCode类获取验证码（判断时忽略大小写 ）
使用session保存验证码的text,与用户输入的进行判断。
2.验证码的刷新：在前端进行验证码路径进行更换
3.免登陆：用户登录后使用session保存用户的2用户名密码等信息。
4.登陆退出：即清除服务器的session，并重定向到登录的页面。

VerifyCode.java

package 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.FileNotFoundException;
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();
	// 定义有那些字体
	private String[] fontNames = { "宋体", "华文楷体", "黑体", "微软雅黑", "楷体_GB2312" };
	// 定义有那些验证码的随机字符
	private String codes = "23456789abcdefghjkmnopqrstuvwxyzABCDEFGHJKLMNOPQRSTUVWXYZ";
	// 生成背景色
	private Color bgColor = new Color(250, 250, 250);
	// 用于gettext 方法 获得生成的验证码文本
	private String text;
 
	// 生成随机颜色
	private Color randomColor() {
		int red = r.nextInt(150);
		int green = r.nextInt(150);
		int blue = r.nextInt(150);
		return new Color(red, green, blue);
	}
 
	// 生成随机字体
	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);
	}
 
	// 画干扰线
	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));// 不知道
			g2.setColor(Color.blue);
			g2.drawLine(x1, y1, x2, y2);
		}
	}
 
	// 得到codes的长度内的随机数 并使用charAt 取得随机数位置上的codes中的字符
	private char randomChar() {
		int index = r.nextInt(codes.length());
		return codes.charAt(index);
	}
 
	// 创建一张验证码的图片
	public BufferedImage createImage() {
		BufferedImage image = new BufferedImage(w, h,
				BufferedImage.TYPE_INT_RGB);
		Graphics2D g2 = (Graphics2D) image.getGraphics();
		StringBuilder sb = new StringBuilder();
		// 向图中画四个字符
		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);
 
		// 返回图片
		return image;
 
	}
 
	// 得到验证码的文本 后面是用来和用户输入的验证码 检测用
	public String getText() {
		return text;
	}
 
	// 定义输出的对象和输出的方向
	public static void output(BufferedImage bi, OutputStream fos)
			throws FileNotFoundException, IOException {
		ImageIO.write(bi, "JPEG", fos);
	}
}

VerifyServlet.java

package com.wang.servlet;

import java.awt.image.BufferedImage;
import java.io.IOException;

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

public class VerifyServlet extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// 生成验证码对象
		VerifyCode code = new VerifyCode();
		BufferedImage image = code.createImage();
		String text = code.getText();
		request.getSession().setAttribute("session_value", text);
		System.out.println("执行ver验证码--"+text);
		VerifyCode.output(image, response.getOutputStream());
	}
}

LoginServlet

package com.wang.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.jms.Session;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class LoginServlet extends HttpServlet {

	// session 的最大不活动时间。
	public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// 判断验证码是否一样 。
		String session_input_code = request.getParameter("verify");
		String session_code = (String) request.getSession().getAttribute("session_value");
		// 判断
		if (!session_code.equalsIgnoreCase(session_input_code)) {
			System.out.println("登录失败！");
			request.setAttribute("err_info", "验证码错误！");
			request.getRequestDispatcher("login.jsp").forward(request, response);
			return;
		}
		final String Myname = "wang";
		final String Mypassword = "121";
		String name = request.getParameter("username");
		String password = request.getParameter("password");
		if (name.equals(Myname) && password.equals(Mypassword)) {
			// 保存session到服务器，转发到成功的页面
			HttpSession session = request.getSession();
			session.setAttribute("username", "wang");// 保存session
			session.setAttribute("password", "121");
			// 重定向
			request.getRequestDispatcher("/succ1.jsp").forward(request, response);
		} else {
			String err_info_1 = "";
			String err_info_2 = "";
			if (!name.equals(Myname)) {
				err_info_1 = "用户名错误！";
			}
			if (!password.equals(Mypassword)) {
				err_info_2 = "密码错误！";
			}
			String err_info_ouput = err_info_1 + err_info_2;
			// 重定向到login.jsp 并使用request域传递错误 的信息
			/*
			 * 这里发送的错误信息必须使用转发，使用重定向会导致获取不到request域的信息
			 */
			request.setAttribute("err_info", err_info_ouput);
			request.getRequestDispatcher("/login.jsp").forward(request, response);
		}
	}
}

exitServlet.java

package com.wang.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;

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

/*
 * 退出Servlet
 */
public class exitServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		request.getSession().invalidate();
		String path = request.getServletContext().getContextPath();
		//
		response.sendRedirect("/demo/login.jsp");
	}

}

login.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
	String path = request.getContextPath();
	String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort()
			+ path + "/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<style type="text/css">
* {
	padding: 0px;
	margin: 0px;
	text-align: center;
	margin-top: 20px;
}
</style>
<body>
	<form action="<%=basePath%>LoginServlet" method="post">
		用户名：<input type="text" name="username"><br> 密码：<input
			type="text" name="password"><br> 验证码：<input type="text"
			name="verify" size="3" ><br> <img
			src="<%=basePath%>VerifyServlet" id="img"><br> </a> <a
			href="javascript:change_verify()">看不清?换一张</a><input type="submit"
			value="提交">
	</form>
	<%
		int index = 0;
		String err_info = (String) request.getAttribute("err_info");
		if (err_info == null) {
			err_info = "";
		}
		Enumeration enumeration = session.getAttributeNames();
		while (enumeration.hasMoreElements()) {
			String name = enumeration.nextElement().toString();
			String value = (String) session.getAttribute(name);

			if (value.equals("wang") || value.equals("121")) {
				index++;
			}
		}
		if (index == 2) {
			request.getRequestDispatcher("/succ1.jsp").forward(request, response);
		}
	%>
	<%=err_info%>
</body>
<script type="text/javascript">

	function change_verify() {
		//获取验证码图片
		var image = document.getElementById("img");
		//更改路径
		image.src = "VerifyServlet?a=" + new Date().getTime();
		console.log(image.src);
	}
</script>
</html>

succ1.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
	String path = request.getContextPath();
	String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort()
			+ path + "/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">

<title>page2</title>

<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
</head>
<body>
	<h1>这里是登录的成功的页面1</h1>
	<%
		//判断是是否有 用户登录后保存的session
		String username = (String) session.getAttribute("username");
		if (username == null) {
			//如果没有 提供 错误的信息“未登录”，并重定向到login.jsp
			request.setAttribute("err_info", "请登录！");
			request.getRequestDispatcher("/login.jsp").forward(request, response);
		}
	%>
	你的名字是：<%=username%>
	<br>
	<a href="<%=basePath%>succ2.jsp">点击跳转到succ2.jsp</a>
	<a href="<%=basePath%>exitServlet">退出登录</a>
</body>
</html>

succ2.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
	String path = request.getContextPath();
	String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort()
			+ path + "/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">

<title>My JSP 'b.jsp' starting page</title>

<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">

</head>

<body>
	<%
		//判断是是否有 用户登录后保存的session
		String username = (String) session.getAttribute("username");
		if (username == null) {
			//如果没有 提供 错误的信息“未登录”，并重定向到login.jsp
			request.setAttribute("err_info", "请登录！");
			request.getRequestDispatcher("/login.jsp").forward(request, response);
		}
	%>
	<h1>这里是登录成功的页面2</h1>
</body>
</html>

项目结构：