最近有时间，就整理整理自己做过的项目或作业~ 该作业的码云链接：https://gitee.com/sarah0429/studentManagement.git

话不多说，直接进入正题。

1.登录

jsp页面代码

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>用户登录</title>

<!-- 取消注释即可实现验证码登录验证 -->
<%-- <script type="text/javascript">
   function reloadCode()
        {
            var time=new Date().getTime();
            document.getElementById("imagecode").src="<%= request.getContextPath()%>/servlet/ImageServlet?d="+time;
       }
    </script> --%>
    
</head>
<body>
<h1>学生信息管理登录</h1>

<!-- 以form表单形式提交，运用其action属性，提交输入的账号密码到<%= request.getContextPath()%>/servlet/LoginServlet下进行处理，
其中<%= request.getContextPath()%>为获取web项目的根路径 -->
	<form action="<%= request.getContextPath()%>/servlet/LoginServlet" method="get" >	
		
		<!-- 账号密码 -->
		UserName:<input type="text" name="username" maxlength="11" size="20">
		Password:<input type="password" name="password" maxlength="11" size="21">
		 		
		 <!-- 取消注释即可实现验证码登录验证 -->
		<%--验证码:<input  type="text" name="checkCode"/>
   	 	<img alt="验证码" id="imagecode" src="<%= request.getContextPath()%>/servlet/ImageServlet"/>
   	 	<a href="javascript:reloadCode();">看不清楚</a>--%>
   	 	
    	<input type="submit" value="提交">
	</form> 
</body>
</html>

登录验证loginservlet代码

package dao;

import java.io.IOException;
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 javax.servlet.http.HttpSession;

@WebServlet("/LoginServlet")

public class LoginServlet extends HttpServlet {

    /**
	 * 
	 */
	private static final long serialVersionUID = 4069971059282821774L;

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

        //设置编码格式，确保发往服务器的参数以utf-8的编码来提取
        request.setCharacterEncoding("utf-8");

		//取消注释即可实现验证码
        /*String piccode=(String) request.getSession().getAttribute("piccode");
        String checkCode=request.getParameter("checkCode");  //取值
        checkCode=checkCode.toUpperCase();  //把字符全部转换为大写的（此语句可以用于验证码不区分大小写）*/
        
        //获取input标签输入的账号密码值，注意request.getParameter("XXX")与该标签下name属性值XXX相同
        String userName = request.getParameter("username");
        String userPwd = request.getParameter("password");
        
        //取消注释即可实现验证码登录验证
        //if(checkCode.equals(piccode)) {

		//验证账号密码是否正确
        if(StudentDao.checkLogin(userName, userPwd)) {

            HttpSession session = request.getSession();

            session.setAttribute("loginName", userName);

            response.sendRedirect("../show.jsp");
        } 
        }else {
 
            response.sendRedirect("../fail.html");
        }
    //}

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

生成验证码ImageServlet代码

package dao;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


@WebServlet("/ImageServlet")
public class ImageServlet  extends HttpServlet{
    /**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException{
    	request.setCharacterEncoding("utf-8");
        //这个方法实现验证码的生成
        BufferedImage bi=new BufferedImage(68, 22,BufferedImage.TYPE_INT_RGB);//创建图像缓冲区
         Graphics g=bi.getGraphics(); //通过缓冲区创建一个画布
         Color c=new Color(200,150,255); //创建颜色
         /*根据背景画了一个矩形框
          */
         g.setColor(c);//为画布创建背景颜色
         g.fillRect(0, 0, 68,22); //fillRect:填充指定的矩形
         
         char[] ch="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789".toCharArray();//转化为字符型的数组
         Random r=new Random();
         int len=ch.length;
         int index; //index用于存放随机数字
         StringBuffer sb=new StringBuffer();
         for(int i=0;i<4;i++)
         {
             index=r.nextInt(len);//产生随机数字
             g.setColor(new Color(r.nextInt(88),r.nextInt(188),r.nextInt(255)));  //设置颜色
             g.drawString(ch[index]+"",(i*15)+3, 18);//画数字以及数字的位置
             sb.append(ch[index]);
         }
         String string = new String(sb.toString().getBytes(),"utf-8");
         request.getSession().setAttribute("piccode",string); //将数字保留在session中，便于后续的使用
         ImageIO.write(bi, "JPG", response.getOutputStream()); 
    }
}