学生信息的添加 Java web简单项目初试（修改）

2022-09-29 18:57:36

错误原因：

1.Java web 的Servlet类没有配置好，并且缺少一个 Dao类（Date Access Object通常用于操作数据库的）.

2.代码的某些名称错误，导致数据库数据存储错误。

添加的Dao类如下：

 package com.Dao;

 import java.sql.Connection;

 import java.sql.PreparedStatement;

 import java.sql.ResultSet;

 import java.sql.SQLException;

 import java.sql.Statement;

 import java.util.ArrayList;

 import java.util.List;

 import com.DBUtil.UserDBUtil;

 import jdk.nashorn.internal.ir.RuntimeNode.Request;

 public class Dao {

     public boolean add(String username,String password,String name,String studentID,String sex,String phone,String email,String xueyuan,String xi,String classes,String year,String shengyuandi,String beizhu) {

         String sql = "insert into use02  values ('" + username + "','" + password +"','" + name +"','" +studentID +"','" + sex +"','" +phone +"','" + email +"','" +xueyuan +"','"+xi +"','"+classes +"','"+year+"','"+shengyuandi +"','"+beizhu +"')";

          // 创建数据库链接

         Connection conn = UserDBUtil.getConnection();

         Statement state = null;

         boolean f = false;

         int a = 0;

         try {

             state = conn.createStatement();

             a = state.executeUpdate(sql);

         } catch (Exception e) {

             e.printStackTrace();

         } finally {

              // 关闭z 连接

             //DB.close(state, conn);

         }

         if (a > 0) {

             f = true;

         }

         return f;

     }

 }

修改后的Servlet代码如下：

 import java.io.IOException;

 import javax.servlet.ServletException;

 import javax.servlet.ServletRequest;

 import javax.servlet.annotation.WebServlet;

 import javax.servlet.http.HttpServlet;

 import javax.servlet.http.HttpServletRequest;

 import javax.servlet.http.HttpServletResponse;

 import com.Dao.*;

 import com.DBUtil.*;

 /**

  * Servlet implementation class UserServlet

  */

 @WebServlet("/AddServlet")

 public class AddServlet extends HttpServlet {

     private static final long serialVersionUID = 1L;

     /**

      * @see HttpServlet#HttpServlet()

      */

     public AddServlet() {

         super();

         // TODO Auto-generated constructor stub

     }

     Dao dao = new Dao();

     protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

         req.setCharacterEncoding("utf-8");

         String method = req.getParameter("method");

         if ("add".equals(method)) {

             add(req, resp);

             System.out.println("!!!");

         }

     }

     private void add(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException {

         // TODO Auto-generated method stub

         String username = req.getParameter("username");

          String password = req.getParameter("password");

         String name = req.getParameter("name");

         String studentID = req.getParameter("studentID");

         String sex = req.getParameter("sex");

         String phone = req.getParameter("phone");

         String email = req.getParameter("email");

         String xueyuan = req.getParameter("xueyuan");

         String xi = req.getParameter("xi");

         String classes = req.getParameter("classes");

         String year = req.getParameter("year");

         String shengyuandi = req.getParameter("shengyuandi");

         String beizhu = req.getParameter("beizhu");

         if(dao.add(username,password,name,studentID,sex,phone,email,xueyuan,xi,classes,year,shengyuandi,beizhu)) {

             req.setAttribute("message", "注册成功!");

             req.getRequestDispatcher("index1.jsp").forward(req, resp);

             return;

         }else {

             req.setAttribute("message", "账号重复，请重新输入!");

             req.getRequestDispatcher("index1.jsp").forward(req, resp);

             return;

         }

         //req.getRequestDispatcher("index1.jsp").forward(req, resp);

     }

 }

bean类

 public class User {

     private String username;

     private String password;

     private String name;

     private String studentID;

     private String sex;

     private String phone;

     private String email;

     private String xueyuan;

     private String xi;

     private String classes;

     private String year;

     private String shengyuandi;

     private String beizhu;

     public String getUsername() {

         return username;

     }

     public void setUsername(String username) {

         this.username = username;

     }

     public String getPassword() {

         return password;

     }

     public void setPassword(String password) {

         this.password = password;

     }

     public String getName() {

         return name;

     }

     public void setName(String name) {

         this.name = name;

     }

     public String getStudentID() {

         return studentID;

     }

     public void setStudentID(String studentID) {

         this.studentID = studentID;

     }

     public String getSex() {

         return sex;

     }

     public void setSex(String sex) {

         this.sex = sex;

     }

     public String getPhone() {

         return phone;

     }

     public void setPhone(String phone) {

         this.phone = phone;

     }

     public String getEmail() {

         return email;

     }

     public void setEmail(String email) {

         this.email = email;

     }

     public String getXueyuan() {

         return xueyuan;

     }

     public void setXueyuan(String xueyuan) {

         this.xueyuan = xueyuan;

     }

     public String getXi() {

         return xi;

     }

     public void setXi(String xi) {

         this.xi = xi;

     }

     public String getClasses() {

         return classes;

     }

     public void setClasses(String classes) {

         this.classes = classes;

     }

     public String getYear() {

         return year;

     }

     public void setYear(String year) {

         this.year = year;

     }

     public String getShengyuandi() {

         return shengyuandi;

     }

     public void setShengyuandi(String shengyuandi) {

         this.shengyuandi = shengyuandi;

     }

     public String getBeizhu() {

         return beizhu;

     }

     public void setBeizhu(String beizhu) {

         this.beizhu = beizhu;

     }

     public User(String username, String password, String name, String studentID, String sex, String phone, String email,

             String xueyuan, String xi, String classes, String year, String shengyuandi, String beizhu) {

         super();

         this.username = username;

         this.password = password;

         this.name = name;

         this.studentID = studentID;

         this.sex = sex;

         this.phone = phone;

         this.email = email;

         this.xueyuan = xueyuan;

         this.xi = xi;

         this.classes = classes;

         this.year = year;

         this.shengyuandi = shengyuandi;

         this.beizhu = beizhu;

     }

 }

数据库连接程序：

 import java.sql.Connection;

 import java.sql.DriverManager;

 //import java.sql.ResultSet;

 import java.sql.SQLException;

 //import java.sql.Statement;

 public class UserDBUtil {

     static Connection con;

     public static Connection getConnection() {

         try {

             Class.forName("com.mysql.cj.jdbc.Driver");

             System.out.println("数据库驱动加载成功");

         } catch (ClassNotFoundException e) {

             // TODO Auto-generated catch block

             e.printStackTrace();

         }

         try {

             con=DriverManager.getConnection("jdbc:mysql://localhost:3306/user?useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B88&serverTimezone=GMT%2B8&useSSL=false","root","101032");

             System.out.println("数据库链接成功！");

         } catch (SQLException e) {

             // TODO Auto-generated catch block

             e.printStackTrace();

         }

         return con;

         }

      public static void main(String[] args) {

          UserDBUtil c=new UserDBUtil();

          c.getConnection();

     }

jsp 页面源代码实现：

 <%@ page language="java" contentType="text/html; charset=UTF-8"

     pageEncoding="UTF-8"%>

 <!DOCTYPE html>

 <html>

 <head>

 <meta charset="UTF-8">

 <title>用户注册</title>

 </head>

 <body>

 <script type="text/javascript" src="./js/jquery-3.3.1.min.js"></script>

 <div class="container">

     <section>

         <form action="AddServlet?method=add" method="post" onsubmit="return check(this)">

             <span class="username">登陆账号</span>

                 <input type="text" name="username" placeholder="  username" id="username">

             <br/>

             <span class="password">登陆密码</span>

             <input type="password" name="password" placeholder="  password" id="password">

             <br/>

             <span class="name">姓名</span>

                 <input type="text" name="name" placeholder="  name" id="name">

             <br/>

             <span class="studentID">学号</span>

             <input type="text" name="studentID" placeholder="  studentID" id="studentID" >

             <br/>

             <span class="sex">性别</span>

                 <input type="radio" name="sex" id="sexnan" value="M">男

                 &nbsp;

                 <input type="radio" name="sex" id="sexnv" value="F">女

             <br/>

 <!--             <span class="diqu">地区</span> -->

 <!--             <select name="diqu"> -->

 <!--                   <option value ="北京市">北京市</option> -->

 <!--                   <option value ="天津市">天津市</option> -->

 <!--                   <option value="河北省">河北省</option> -->

 <!--             </select> -->

 <!--             <br/> -->

             <span class="phone">手机号</span>

                 <input type="text" name="phone" placeholder="  phone" id="phone">

             <br/>

             <span class="email">邮箱</span>

                 <input type="text" name="email" placeholder="  email" id="email">

             <br/>

             <span class="xueyuan">所在学院：</span>

             <input type="text" name="xueyuan" placeholder="  xueyuan" id="xueyuan">

             <br/>

             <span class="xi">所在系：</span>

             <input type="text" name="xi" placeholder="  suozaixi" id="xi">

             <br/>

             <span class="classes">所在班级：</span>

             <input type="text" name="classes" placeholder="  classes" id="classes">

             <br/>

             <span class="year">入学年份（届）：</span>

             <select name="year">

             <option value ="2014">2014</option>

                   <option value ="2015">2015</option>

                   <option value ="2016">2016</option>

                   <option value="2017">2017</option>

                   <option value="2018">2018</option>

                   <option value ="2019">2019</option>

                   </select>

             <br/>

             <span class="shengyuandi">生源地：</span>

             <input type="text" name="shengyuandi" placeholder="  shengyuandi" id="shengyuandi">

             <br/>

             <span class="beizhu">备注：</span>

             <input type="text" name="beizhu" placeholder="  beizhu" id="beizhu">

             <br/>

             <input type="submit" value="保存" class="butn">

 <!--             <input type="reset" value="重置" class="butn"> -->

             <br/>

         </form>

     </section>

 </div>

 <script>

     //正则表达式

 function check(form){

     if(form.username.value.length<6 || form.username.value.length>12 || new RegExp("[^0-9a-zA-Z]").test(form.username.value)){

         alert("登陆账号必须由6-12位英文字符或数字组成！");

         form.user.focus();

         return false;

     }

     if(new RegExp("[^a-zA-Z]").test(form.username.value.substring(0,1))){

         alert("登陆账号必须以英文字母开头！");

         form.user.focus();

         return false;

     }

     if(form.password.value.length <= 8 || new RegExp("[^0-9a-zA-Z]").test(form.password.value)){

         alert("密码必须由八位以上字母、数字组成！");

         form.phone.focus();

         return false;

     }

     if(form.studentID.value.length != 8 || new RegExp("[^0-9]").test(form.studentID.value)){

         alert("请输入八位学号！");

         form.phone.focus();

         return false;

     }

     if(form.phone.value.length != 11 || new RegExp("[^0-9]").test(form.phone.value)){

         alert("手机号请输入11位数字！");

         form.phone.focus();

         return false;

     }

     //以数字字母开头，中间可以是多个数字字母或下划线；然后是“@”；然后是数字字母；然后是“.”；最后是2-4个字母结尾

     var regex = /^([a-zA-Z]|[0-9])(\w|\-)+@[a-zA-Z0-9]+\.([a-zA-Z]{2,4})$/;

     if(!regex.test(form.email.value)){

         alert("邮箱格式错误！");

         form.email.focus();

         return false;

     }

     return true;

 }

 </script>

 </body>

 </html>

数据库存储界面：

对于Java web数据库连接的理解：

Java类：

1.servlet 类处理从前端接受的信息，即jsp 与数据库连接的接口

2.DBUtil 类加载数据库驱动，建立对数据库的连接。

3.Dao 类实现对数据库的增删改查

4.Bean 类存储信息的基础类

5.在lib目录下导入需要的jar的包

6. jsp 实现界面。

本人目前处于初学阶段，代码大部分都是对模板进行修改，没有完全理解，仍旧有许多需要学习的地方。

数据库的JDBC桥接：

面向对象的应用程序接口，制定了统一的访问各种关系型数据库的标准接口。

JDBC任务：

1.与数据库建立连接

2.向数据库发生sql语句

3.处理从数据库返回的结果

以下是之前的错误代码：

https://www.cnblogs.com/cxy0210/p/11715924.html

以上代码如有错误，敬请指正，感激不尽。

码农公寓

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