JSP实现学生管理系统

JSP实现学生管理系统

登录功能

1. 创建一个web项目
2. 在web目录下创建一个index.jsp
3. 在页面中获取会话域中的用户名，获取到了就显示添加和查看功能的超链接，没获取到就显示登录功能
4. 在web目录下创建一个login.jsp。实现登录页面
5. 创建loginServlet，获取用户名和密码
6. 如果用户名为空，则重定向到登录页面
7. 如果不为空，将用户添加到会话域中，在重定向到首页

• 创建一个web项目，在web路径下创建一个index.jsp

<%@ page contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>



    


<%--
    获取会话域中的数据
    如果获取到了则显示添加和查看功能的超连接
    如果没有获取到则显示登录功能的超链接
--%>
    
        请登录
    
    
            添加学生
            查看学生
    

• 在web目录下创建一个login.jsp.实现登录页面

<%--
  Created by IntelliJ IDEA.
  User: heroma
  Date: 2022/1/28
  Time: 5:02 下午
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>


    


    

        姓名：

        密码：

        登录
    

• 创建LoginStudentServlet,获取用户名和密码

  package com.example.jsp_demo.servlet;
  
  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 java.io.IOException;
  
  @WebServlet("/login")
  public class LoginStudentServlet extends HttpServlet {
      @Override
      protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
          //1.获取用户名和密码
          String username = req.getParameter("username");
          String password = req.getParameter("password");
          //2.判断用户名
          if (username == null || username.equals("")){
              resp.sendRedirect("/stu/login.jsp");
              return;
          }
          //3.用户名不为空，将用户名存入会话域中
          req.getSession().setAttribute("username", username);
          //4. 重定向到首页
          resp.sendRedirect("/stu/index.jsp");
      }
  
      @Override
      protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
          doGet(req,resp);
      }
  }
  

添加功能实现

• 在web目录下创建一个addStudent.jsp，实现添加学生的表单项

<%--
  Created by IntelliJ IDEA.
  User: heroma
  Date: 2022/1/28
  Time: 5:04 下午
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%%>


    


    

        学生姓名：

        学生年龄：

        学生成绩：

        保存
    

• 创建AddStudentServlet，获取并保存到文件夹中

  package com.example.jsp_demo.servlet;
  
  import com.example.jsp_demo.bean.Student;
  
  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 java.io.BufferedWriter;
  import java.io.FileWriter;
  import java.io.IOException;
  
  @WebServlet("/add")
  public class AddStudentServlet extends HttpServlet {
      @Override
      protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
          //1.获取表单中的数据
          String username = req.getParameter("username");
          String age = req.getParameter("age");
          String score = req.getParameter("score");
          //2.创建学生对象并赋值
          Student student = new Student(username, Integer.parseInt(age), Integer.parseInt(score));
          //3.将学生对象保存到文件中
          String realPath = getServletContext().getRealPath("/resource/stu.txt");
          System.out.println(realPath);
          BufferedWriter bw = new BufferedWriter(new FileWriter(realPath,true));
          bw.write(student.getUsername() + "," + student.getAge() + "," + student.getScore());
          bw.newLine();
          bw.close();
          //4.通过定时刷新功能相应给浏览器
          //resp.setContentType("text/html;charset=UTF-8");
          resp.getWriter().write("添加成功，1秒后自动跳转首页......");
          resp.setHeader("Refresh","1;URL=/stu/index.jsp");
      }
  
      @Override
      protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
          doGet(req,resp);
      }
  }
  

查看学生功能

• 创建ListStudentServlet，读取文件中的学生信息到消息集合中

  package com.example.jsp_demo.servlet;
  
  import com.example.jsp_demo.bean.Student;
  
  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 java.io.*;
  import java.util.ArrayList;
  
  @WebServlet("/list")
  public class ListStudentServlet extends HttpServlet {
      @Override
      protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
          //1.创建字符输入流，关联相关文件
          String realPath = getServletContext().getRealPath("/resource/stu.txt");
          System.out.println(realPath);
          BufferedReader br = new BufferedReader(new FileReader(realPath));
          //2.创建集合对象，用来保存学生对象
          ArrayList students = new ArrayList<>();
          //3.循环读取文件中的数据，将数据封装到student对象中，再把多个学生对象添加到集合中
          String line;
          while ((line = br.readLine()) != null ){
              String[] s = line.split(",");
              Student student = new Student(s[0], Integer.parseInt(s[1]), Integer.parseInt(s[2]));
              students.add(student);
          }
          //4.将集合对象保存到会话中去
          req.getSession().setAttribute("students",students);
          //5.将页面重定向到学生列表页面
          resp.sendRedirect("/stu/list.jsp");
      }
  
      @Override
      protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
          super.doPost(req, resp);
      }
  }
  

• 在web目录下创建一个list.jsp

<%@ page import="java.util.ArrayList" %>
<%@ page import="com.example.jsp_demo.bean.Student" %><%--
  Created by IntelliJ IDEA.
  User: heroma
  Date: 2022/1/28
  Time: 5:41 下午
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>


    


    
            

        

            
学生姓名
            
学生年龄
            
学生成绩
        
        

                
${s.username}
                
${s.age}
                
${s.score}
            
        
    

• 通过过滤器解决乱码问题

package com.example.jsp_demo.filter;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Enumeration;

@WebFilter("/*")
public class EncodingFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
       
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        //1.将请求和响应转化为http协议相关的
        HttpServletRequest req = (HttpServletRequest) servletRequest;
        HttpServletResponse resp = (HttpServletResponse) servletResponse;
        //2.设置编码格式
        req.setCharacterEncoding("UTF-8");
        resp.setContentType("text/html;charset=UTF-8");
        //3.执行
        filterChain.doFilter(req,resp);
    }

    @Override
    public void destroy() {

    }
}

• 登录校验

package com.example.jsp_demo.filter;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebFilter(value = {"/addStudent.jsp", "/list"})
public class LoginFilter implements Filter {
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        //1.将请求和响应转化为http协议相关的
        HttpServletRequest req = (HttpServletRequest) servletRequest;
        HttpServletResponse resp = (HttpServletResponse) servletResponse;
        //2.获取会话域对象数据
        Object username = req.getSession().getAttribute("username");
        System.out.println(username);
        //3.判断用户名
        if (username == null || "".equals(username)){
            resp.sendRedirect(req.getContextPath() + "/login.jsp");
            return;
        }
        //4.放行
        filterChain.doFilter(req,resp);
    }
}