驗證碼.md

驗證碼

生成圖片(VerifyCode 類)

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"};
	// 可选字符
	private String codes  = "23456789abcdefghjkmnopqrstuvwxyzABCDEFGHJKMNPQRSTUVWXYZ";
	// 背景色
	private Color bgColor  = new Color(255, 255, 255);
	// 验证码上的文本
	private String text ;
	
	// 生成随机的颜色
	private Color randomColor () {
		int red = r.nextInt(150);
		int green = r.nextInt(150);
		int blue = r.nextInt(150);
		return new Color(red, green, blue);
	}
	
	// 生成随机的字体
	private Font randomFont () {
		int index = r.nextInt(fontNames.length);
		String fontName = fontNames[index];//生成随机的字体名称
		int style = r.nextInt(4);//生成随机的样式, 0(无样式), 1(粗体), 2(斜体), 3(粗体+斜体)
		int size = r.nextInt(5) + 24; //生成随机字号, 24 ~ 28
		return new Font(fontName, style, size);
	}
	
	// 画干扰线
	private void drawLine (BufferedImage image) {
		int num  = 3;//一共画3条
		Graphics2D g2 = (Graphics2D)image.getGraphics();
		for(int i = 0; i < num; i++) {//生成两个点的坐标，即4个值
			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); //干扰线是蓝色
			g2.drawLine(x1, y1, x2, y2);//画线
		}
	}
	
	// 随机生成一个字符
	private char randomChar () {
		int index = r.nextInt(codes.length());
		return codes.charAt(index);
	}
	
	// 创建BufferedImage
	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;
	}
	
	// 调用这个方法得到验证码
	public BufferedImage getImage () {
		BufferedImage image = createImage();//创建图片缓冲区 
		Graphics2D g2 = (Graphics2D)image.getGraphics();//得到绘制环境
		StringBuilder sb = new StringBuilder();//用来装载生成的验证码文本
		// 向图片中画4个字符
		for(int i = 0; i < 4; i++)  {//循环四次，每次生成一个字符
			String s = randomChar() + "";//随机生成一个字母 
			sb.append(s); //把字母添加到sb中
			float x = i * 1.0F * w / 4; //设置当前字符的x轴坐标
			g2.setFont(randomFont()); //设置随机字体
			g2.setColor(randomColor()); //设置随机颜色
			g2.drawString(s, x, h-5); //画图
		}
		this.text = sb.toString(); //把生成的字符串赋给了this.text
		drawLine(image); //添加干扰线
		return image;		
	}
	
	// 返回验证码图片上的文本
	public String getText () {
		return text;
	}
	
	// 保存图片到指定的输出流
	public static void output (BufferedImage image, OutputStream out) 
				throws IOException {
		ImageIO.write(image, "JPEG", out);
	}
}

登錄功能之添加驗證碼

//LoginServlet
import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
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 {
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		/*
		 * 校验验证码
		 * 1. 从session中获取正确的验证码
		 * 2. 从表单中获取用户填写的验证码
		 * 3. 进行比较！
		 * 4. 如果相同，向下运行，否则保存错误信息到request域，转发到login.jsp
		 */
		String sessionCode = (String) request.getSession().getAttribute("session_vcode");
		String paramCode = request.getParameter("verifyCode");
		
		if(!paramCode.equalsIgnoreCase(sessionCode)) {
			request.setAttribute("msg", "验证码错误！");
			request.getRequestDispatcher("/session2/login.jsp").forward(request, response);
			return;
		}
		
		
		/*
		 * 1. 获取表单数据
		 */
		// 处理中文问题
		request.setCharacterEncoding("utf-8");
		// 获取
		String username = request.getParameter("username");
		String password = request.getParameter("password");
		/*
		 * 2. 校验用户名和密码是否正确
		 */
		if(!"itcast".equalsIgnoreCase(username)) {//登录成功
			/*
			 * 附加项：把用户名保存到cookie中，发送给客户端浏览器
			 * 当再次打开login.jsp时，login.jsp中会读取request中的cookie，把它显示到用户名文本框中
			 */
			Cookie cookie = new Cookie("uname", username);//创建Cookie
			cookie.setMaxAge(60*60*24);//设置cookie命长为1天
			response.addCookie(cookie);//保存cookie
			
			/*
			 * 3. 如果成功
			 *   >  保存用户信息到session中
			 *   >  重定向到succ1.jsp
			 */
			HttpSession session = request.getSession();//获取session
			session.setAttribute("username", username);//向session域中保存用户名
			response.sendRedirect("/Java_Web/session2/succ1.jsp");
		} else {//登录失败
			/*
			 * 4. 如果失败
			 *   > 保存错误信息到request域中
			 *   > 转发到login.jsp
			 */
			request.setAttribute("msg", "用户名或密码错误!");
			RequestDispatcher qr = request.getRequestDispatcher("/session2/login.jsp");//得到转发器
			qr.forward(request, response);//转发
		}
	}
}

//VerifyCodeServlet
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.PrintWriter;

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

import image.VerifyCode;

public class VerifyCodeServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		/*
		 * 1. 生成圖片
		 * 2. 保存圖片上的文本保存到 session 域中
		 * 3. 把圖片響應給客戶端
		 */
		VerifyCode vc = new VerifyCode();
		BufferedImage bi = vc.getImage();
		request.getSession().setAttribute("session_vcode", vc.getText()); //保存圖片上的文本到 session 域中
		
		VerifyCode.output(bi, response.getOutputStream());
	}
}

//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 'login.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">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
	<script type="text/javascript">
		function _change() {
			/*
			1. 得到 image 元素
			2. 修改其 src 為 /Java_Web/VerifyCodeServlet
			*/
			var imgEle = document.getElementById(img);
			imgEle.src = "/Java_Web/VerifyCodeServlet?a=" + new Date().getTime();
		}
	</script>

  </head>
  
  <body>
  	<%-- 本頁面提供登錄表單，還要顯示錯誤信息 --%>
  	<h1>登錄</h1>
  	<%
  		/*
  		 * 讀取名為 uname 的 Cookie
  		 * 如果為空顯示: ""
  		 * 如果不為空顯示: Cookie 的值
  		 */
  		String uname = "";
  		Cookie[] cs = request.getCookies();
  		if(cs != null) { //如果存在 Cookie
  			for(Cookie c : cs) { //循環遍歷所有 Cookie
  				if("uname".equals(c.getName())) { //查找名為 uname 的 Cookie
  					uname = c.getValue(); //獲取這個 Cookie 的值，給 uname 這個變量
  				}
  			}
  		}
  	%>
  	<%
  		String message = "";
  		String msg = (String)request.getAttribute("msg"); //獲取 request 域中名為 msg 的屬性
  		if(msg != null) {
  			message = msg;
  		}
  	%>
  	<font color="red"><b><%=message %></b></font>
  	<form action="/Java_Web/LoginServlet" method="post">
  				<%-- 把 Cookie 中的用戶名顯示到用戶名文本框中 --%>
  		用戶名: <input type="text" name="username" value="<%=uname%>"><br>
  		密   碼: <input type="password" name="password"><br>
  		驗證碼: <input type="text" name="verifycode">
				<img id="img" src="/Java_Web/VerifyCodeServlet">
				<a href="javascript:_change()">換一張</a>
  		<input type="submit" value="登錄">
  	</form>
  </body>
</html>