12月11日学习日志

今天学习了java web学生信息系统的修改操作。

jsp代码如下：

<%@page import="com.servlet.Student" %>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<%
    Student s=(Student)request.getAttribute("student");
%>
<form action="editsuccess" method="post">
<input type="hidden" name="id" value="<%=s.getId()%>"><br>
    姓名:<input type="text" name="name"><br>
    年龄:<input type="text" name="age"><br>
    学号:<input type="text" name="num"><br>
<input type="submit" value="提交">
</form>
</body>
</html>

servlet代码如下：

package com.servlet;

import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

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 com.jdbc.jdbcUtil;

/**
 * Servlet implementation class edit
 */
@WebServlet("/edit")
public class edit extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public edit() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        Integer id=Integer.parseInt(request.getParameter("id").toString());
        try {
            Connection con=jdbcUtil.getcon();
            String sql="select * from stu where id=?";
            PreparedStatement pst=con.prepareStatement(sql);
            pst.setInt(1, id);
            ResultSet rs=pst.executeQuery();
            Student s=null;
            while(rs.next()) {
                Integer newid=rs.getInt("id");
                String name=rs.getString("name");
                Integer age=rs.getInt("age");
                String num=rs.getString("num");
                s=new Student(newid,name,age,num);
            }
            jdbcUtil.close(con, pst, null);
            request.setAttribute("student", s);
            request.getRequestDispatcher("edit.jsp").forward(request, response);
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        
    }

}

package com.servlet;

import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

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 com.jdbc.jdbcUtil;

/**
 * Servlet implementation class editsuccess
 */
@WebServlet("/editsuccess")
public class editsuccess extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public editsuccess() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        request.setCharacterEncoding("utf-8");
        try {
            Connection con=jdbcUtil.getcon();
            String sql="update stu set name=?,age=?,num=? where id=?";
            PreparedStatement pst=con.prepareStatement(sql);
            pst.setString(1, request.getParameter("name"));
            pst.setInt(2, Integer.parseInt(request.getParameter("age").toString()));
            pst.setString(3, request.getParameter("num"));
            pst.setInt(4, Integer.parseInt(request.getParameter("id").toString()));
            pst.executeUpdate();
            jdbcUtil.close(con, pst, null);
            response.sendRedirect(request.getContextPath()+"/list");
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

}

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原文地址：https://www.cnblogs.com/20193925zxt/p/14228658.html