【Java学习20170426】Servlet

最新推荐文章于 2025-03-19 11:45:11 发布

张渔

最新推荐文章于 2025-03-19 11:45:11 发布

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分类专栏： Java学习文章标签： java web java servlet

本文链接：https://blog.youkuaiyun.com/linsila8121/article/details/70821464

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本文介绍了一个基于Servlet的用户注册系统，通过使用session存储验证码并进行校验，以及利用应用范围存储已注册用户信息来避免重复注册。此外，还详细展示了如何生成并显示验证码图片。

Servlet开发

作业：防止重复注册

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
	<form action="process.jsp">
		用户：<input type="text" name="user"><br>
		密码：<input type="password" name="pass"><br>
			<input type="submit" value="注册">
			<input type="reset" value="重置">
	</form>
</body>
</html>

<%@page import="java.util.ArrayList"%>
<%@page import="java.util.List"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
	<%
		String user = request.getParameter("user");
		String pass = request.getParameter("pass");

		List<String> list = (List<String>) application.getAttribute("userMessage");
		boolean flag = true;
		if (list == null) {
			list = new ArrayList<String>();
		} else {
			if (list.contains(user)) {
				flag = false;
				response.sendRedirect("failed.jsp");
			}
		}
		
		if (flag) {
			list.add(user);
			application.setAttribute("userMessage", list);
			response.sendRedirect("success.jsp");
		}
	%>
</body>
</html>

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
	注册成功！
</body>
</html>

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
	注册失败！用户已经存在。
</body>
</html>

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();//获取上下文地址
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>用户注册</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">
		table{
			font-size:12px;
			font-family: 隶书;
			color:gray;
			border: 1px green solid;
		}
		input{
			font-size:12px;
			font-family: 隶书;
			color:gray;
		}
	</style>
  </head>
  
  <body>
  
   	<form action="/SerlvetTest/show" method="post">
   		<table align="center">
   			<tr>
   				<td>用户名：</td>
   				<td><input type="text" name="name" /></td>
   			</tr>
   			<tr>
   				<td>密码：</td>
   				<td><input type="password" name="pwd" /></td>
   			</tr>
   			<tr>
   				<td>性别：</td>
   				<td>
   					<input type="radio" name="sex" value="男" />男
   					<input type="radio" name="sex" value="女" />女
   				</td>
   			</tr>
   			<tr>
   				<td>年龄：</td>
   				<td><input type="text" name="age" /></td>
   			</tr>
   			<tr>
   				<td>Email：</td>
   				<td><input type="text" name="email" /></td>
   			</tr>
   			<tr>
   				<td>验证码：</td>
   				<td>
   					<img alt="网络加载失败" src="validatecode" >
   				</td>
   			</tr>
   			<tr>
   				<td>输入验证码：</td>
   				<td>
   					<input type="text" name="code"/>
   				</td>
   			</tr>
   			<tr>
   				<td colspan="2" align="center">
   					<input type="submit" value="注 册" />
   					<input type="reset" value="重 置" />
   				</td>
   			</tr>
   		</table>
   	</form>
  </body>
</html>

	package com.tx.demo6;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.PrintWriter;
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;
//原因分析：MyEclipse默认把这些访问受限的API当成了错误来处理
//解决办法：在MyEclipse中点Window——>Preferences——>Java——>Compiler——>Errors/Warnings，
//展开Deprecated and restricted API，把Forbidden reference(access rules)后面的选项的Error改为Warning，
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

public class ValidateCodeServlet extends HttpServlet {
	public ValidateCodeServlet() {
		super();
	}
	public void destroy() {
		super.destroy();
	}
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		this.doPost(request, response);
	}

	public Color getRandomColor(int fc, int bc) {
		Random random = new Random();
		Color randomColor = null;
		if (fc > 255)
			fc = 255;
		if (bc > 255)
			bc = 255;
		// 设置个0-255之间的随机颜色值
		int r = fc + random.nextInt(bc - fc);
		int g = fc + random.nextInt(bc - fc);
		int b = fc + random.nextInt(bc - fc);
		randomColor = new Color(r, g, b);
		return randomColor;// 返回具有指定红色、绿色和蓝色值的不透明的 sRGB 颜色
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
			//禁止页面缓存
		 	response.setHeader("Pragma", "No-cache");
			response.setHeader("Cache-Control", "No-cache");
			response.setDateHeader("Expires", 0);
			response.setContentType("image/jpeg");		//设置响应正文的MIME类型为图片
			int width=60, height=20;  
			/**创建一个位于缓存中的图像，宽度60，高度20 */  
			BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);   	
			Graphics g = image.getGraphics();      		//获取用于处理图形上下文的对象，相当于画笔
			Random random = new Random();        		//创建生成随机数的对象
			g.setColor(getRandomColor(200,250));  	  	//设置图像的背景色
			g.fillRect(0, 0, width, height);            //画一个矩形	，坐标（0，0），宽度60，高度20 
			g.setFont(new Font("Times New Roman",Font.PLAIN,18)); 	//设定字体格式
			g.setColor(getRandomColor(160,200));
			for(int i=0;i<130;i++){                     //产生130条随机干扰线
				int x = random.nextInt(width);   
				int y = random.nextInt(height);   
				int xl = random.nextInt(12);   
				int yl = random.nextInt(12);   
				g.drawLine(x,y,x+xl,y+yl);          	//在图象的坐标（x,y）和坐标（x+x1,y+y1）之间画干扰线 
			} 
			String strCode="";  
			for (int i=0;i<4;i++){   
				String strNumber=String.valueOf(random.nextInt(10)); //把随机数转换成String字符串
				strCode=strCode+strNumber;
				//设置字体的颜色
				g.setColor(new Color(15+random.nextInt(120),15+random.nextInt(120),15+random.nextInt(120)));
				System.out.println(strCode);
				g.drawString(strNumber,13*i+6,16);       //将验证码依次画到图像上,坐标（x=13*i+6,y=16）
			}
			request.getSession().setAttribute("Code",strCode);       	//把验证码保存到Session中   
			g.dispose();  //释放此图像的上下文以及它使用的所有系统资源
			ImageIO.write(image, "JPEG", response.getOutputStream()); 	//输出JPEG格式的图像    
			response.getOutputStream().flush();                     	//刷新输出流 
			response.getOutputStream().close();                    		//关闭输出流 
	}
	public void init() throws ServletException {
	}

}

package com.tx.demo6;

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

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

@WebServlet(value="/show")
public class ShowServlet extends HttpServlet{

	@Override
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub

		this.doPost(request, response);
	}
	
	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		request.setCharacterEncoding("UTF-8");
		response.setContentType("text/html;charset=utf-8");
		String code = request.getParameter("code");
		String name = request.getParameter("name");
		String pwd = request.getParameter("pwd");
		String sex = request.getParameter("sex");
		String age = request.getParameter("age");
		String email = request.getParameter("email");
		String servicecode = (String)request.getSession().getAttribute("Code");
		PrintWriter pw = response.getWriter();
		if(servicecode.equals(code)){
			pw.println("账号："+name);
			pw.println("密码："+pwd);
			pw.println("性别："+sex);
			pw.println("年龄："+age);
			pw.println("邮箱："+email);
			
		}else{
			pw.println("验证码错误");
			response.setHeader("refresh", "3;URL=jsp/demo6/index.jsp");
		}
		pw.flush();
		pw.close();
	}
}