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使用idea开发javaWeb应用程序的思路(实现用户的增

来源：互联网收集：自由互联发布时间：2021-04-03

在2.7 节基础上，这一节实现了用户的增删改查操作。完整工程代码：链接: https://pan.baidu.com/s/1zSGMvSQa-ihwEN5pP4vW6w 提取码: dpw8 工程目录结构如下： 1、添加/修改用户页面在webapp下新建目

在2.7 节基础上，这一节实现了用户的增删改查操作。
完整工程代码：
链接: https://pan.baidu.com/s/1zSGMvSQa-ihwEN5pP4vW6w 提取码: dpw8

工程目录结构如下：

在这里插入图片描述

1、添加/修改用户页面

在webapp下新建目录user，用于存放用户相关的页面。
添加和修改使用的是同一个页面，通过url中的参数控制是否是修改操作。
后台通过是否传递了id进行判断新增还是修改。
新建：add.html，代码如下：

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title>登录页面</title>
 <link rel="stylesheet" type="text/css" href="../css/my.css" rel="external nofollow" rel="external nofollow" >
 <script type="text/javascript" src="../js/my.js"></script>
</head>

<body>
<div id="main-container" >
 <div id="div-header" >
  <h3 style="margin-bottom:0;">欢迎进入我的网站</h3>
  </hr>
  <p>
   天将降大任于斯人也，必先苦其心志，劳其筋骨，饿其体肤，空乏其身，行拂乱其所为，所以动心忍性，曾益其所不能。——孟子
  </p>
 </div>
 <div id="div-content" >
  <h3 style="margin-bottom:0;">添加用户</h3>
  <form id="userAddForm" class="userAddForm" action="addUser" method="post">
   <input id="id" type="hidden" name="id" />
   <p>登录账号: <input id="uname" type="text" name="uname" /></p>
   <p>真实姓名: <input id="realName" type="text" name="realName" /></p>
   <p>选择性别: <select id="sex" name="sex" style="width:170px">
    <option id="option_m" value ="男">男</option>
    <option id="option_w" value ="女">女</option>
   </select></p>
   <p>登录密码: <input id="pwd" type="password" name="pwd" /></p>
   <p>确认密码: <input id="pwdRepeat" type="password" name="pwdRepeat" /></p>
   <input type="button" value="提交" onclick="submitAddUser()"/>
  </form>
 </div>


</div>
<script type="text/javascript">

//检查输入是否为非空
function submitAddUser()
{
 var uname = document.getElementById("uname").value;//获取输入的用户名的值
 var pwd = document.getElementById("pwd").value;//获取输入的密码值
 var pwdRepeat = document.getElementById("pwdRepeat").value;//获取输入确认密码值
 var realName = document.getElementById("realName").value;//获取输入的姓名值
 var sex = document.getElementById("sex").value;//获取输入的性别值
 if(uname == "" || pwd == "" || pwdRepeat == "" || realName == "" || sex == "" ){
  alert("请将信息填写完整后再提交。");
  return;
 }
 if( pwd != pwdRepeat){
  alert("两次密码输入不一致，请重新输入。");
 }
 document.getElementById("userAddForm").submit(); //输入不为空则跳转到主页面

}
//从url中获取参数
function getQueryVariable(variable)
{
  var query = window.location.search.substring(1);
  console.log(query);
  var vars = query.split("&");
  for (var i=0;i<vars.length;i++) {
    var pair = vars[i].split("=");
    if(pair[0] == variable){return decodeURI(pair[1]);}
  }
  return(false);
}
//判断参数是否为true，不为true则弹窗提示密码错误。
var bool = getQueryVariable("success");
var operation = getQueryVariable("operation");
if(bool == "false" && operation=="addUser"){
 alert("操作失败。");
}else if(bool == "true" && operation=="addUser"){
 alert("操作成功。");
}
showOld();
//从url中获取参数，回显
function showOld()
{
  var uname = getQueryVariable("uname");
  var realName = getQueryVariable("realName");
  var id = getQueryVariable("id");
  var sex = getQueryVariable("sex");
  var pwd = getQueryVariable("pwd");
  if(id != "" && id != null){
  document.getElementById("uname").value=uname;
  document.getElementById("pwd").value=pwd;
  document.getElementById("pwdRepeat").value = pwd;
  document.getElementById("realName").value = realName;
  document.getElementById("id").value = id;
  if(sex == "男"){
   document.getElementById("option_m").selected = true;
  }else{
   document.getElementById("option_w").selected = true;
  }
  }
}
</script>
</body>
</html>

2、查询用户页面

在user目录下新建list.jsp，代码如下：

<%@page import="java.util.ArrayList"%>
<%@page import="com.my.site.UserEntity"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
 <title>我的网站</title>
 <meta charset="utf-8">
 <link rel="stylesheet" type="text/css" href="../css/my.css" rel="external nofollow" rel="external nofollow" >
</head>
<body>
<!-- jsp 页面可以内嵌 java代码-->
<%
 ArrayList<UserEntity> all = ( ArrayList<UserEntity>)session.getAttribute("all");

%>
<div id="main-container" >
 <div id="div-header" >
  <h3 style="margin-bottom:0;">用户查询</h3>
  </hr>
  <p>
   天将降大任于斯人也，必先苦其心志，劳其筋骨，饿其体肤，空乏其身，行拂乱其所为，所以动心忍性，曾益其所不能。——孟子
  </p>
 </div>
 <div id="div-content" >
  <table border="1" class="table" >
  <tr>
   <td>编号</td>
   <td>用户名</td>
   <td>密码</td>
   <td>真实姓名</td>
   <td>性别</td>
   <td>注册时间</td>
   <td>操作</td>
  </tr>
  <%
   for(UserEntity user:all)
   {%>
   <tr>
    <td ><%=user.getId() %></td>
    <td><%=user.getUname() %></td>
    <td><%=user.getPwd() %></td>
    <td><%= user.getRealName() %></td>
    <td><%= user.getSex() %></td>
    <td><%= user.getAdd_time() %></td>
    <td><a href="del?id=<%=user.getId()%> " rel="external nofollow" >删除</a>
    <a href="add.html?id=<%=user.getId()%>&uname=<%=user.getUname()%>&pwd=<%=user.getPwd()%>&realName=<%=user.getRealName()%>&sex=<%=user.getSex()%>" rel="external nofollow" >修改</a>
    </td>
   </tr>
   <%}
  %>
 </table>
  <p>
   当前时间: <%= (new java.util.Date()).toLocaleString()%>
  </p>
 </div>
</div>
<script type="text/javascript">
//点击按钮跳转到登录页面
function toAddUser()
{
 window.location.href="user/add.html" rel="external nofollow" ;
}
function toSearchUser()
{
 window.location.href="user/list" rel="external nofollow" ;
}
</script>
</body>
</html>

3、编写后台逻辑-添加/修改

新建：UserAdd类

package com.my.site;

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("/user/addUser")
public class UserAdd extends HttpServlet {

 /** req 携带了请求相关信息，包括各种配置和请求参数； resp：携带返回相关信息 */
 @Override
 protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
  //从请求对象中获取请求参数：是从前端 usr/add.html页面的 userAddForm 表单提交过来的
  String uname = new String(req.getParameter("uname").getBytes("ISO-8859-1"),"utf-8");
  String pwd = new String(req.getParameter("pwd").getBytes("ISO-8859-1"),"utf-8");
  String realName = new String(req.getParameter("realName").getBytes("ISO-8859-1"),"utf-8");
  String sex = new String(req.getParameter("sex").getBytes("ISO-8859-1"),"utf-8");
  String pwdRepeat = new String(req.getParameter("pwdRepeat").getBytes("ISO-8859-1"),"utf-8");
  String id_str = req.getParameter("id");
  boolean bool = false;
  //如果有id，就执行更新操作，没有id则执行新增操作
  if(null != id_str && !"".equals(id_str)){
   int id = Integer.parseInt(req.getParameter("id"));
   bool = MySqlOperator.updateUser(id,uname, pwd, realName, sex);
  }else {
    bool = MySqlOperator.addUser(uname, pwd, realName, sex);
  }
  resp.setContentType("text/html;charset=UTF-8");
  if(bool){
   //跳转到主页面，并携带请求体，返回体对象。
   resp.sendRedirect("add.html?operation=addUser&success=true");
  }else{
   //校验失败则跳转到登录页面
   resp.sendRedirect("add.html?operation=addUser&success=false");
  }
 }
 @Override
 protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
  doPost(req, resp);
 }
}

4、编写后台逻辑-查询

新建 UserList 类

package com.my.site;

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;
import java.io.IOException;
import java.util.List;

@WebServlet("/user/list")
public class UserList extends HttpServlet {
 /** req 携带了请求相关信息，包括各种配置和请求参数； resp：携带返回相关信息 */
 @Override
 protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
  List<UserEntity> all = MySqlOperator.listAllUser();
  HttpSession session = req.getSession();
  session.setAttribute("all",all);
  resp.setContentType("text/html;charset=UTF-8");
  resp.sendRedirect("list.jsp");
 }
 @Override
 protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
  doPost(req, resp);
 }
}

5、编写后台逻辑-删除

新建UserDel

package com.my.site;

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("/user/del")
public class UserDel extends HttpServlet {

 /** req 携带了请求相关信息，包括各种配置和请求参数； resp：携带返回相关信息 */
 @Override
 protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
  //从请求对象中获取请求参数：是从前端 usr/add.html页面的 userAddForm 表单提交过来的
  int id = Integer.parseInt(req.getParameter("id").trim());
  MySqlOperator.delUser(id);
  resp.setContentType("text/html;charset=UTF-8");
  resp.sendRedirect("list");
 }

 @Override
 protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
  doPost(req, resp);
 }
}

6、编写数据库操作

package com.my.site;

import java.sql.*;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

public class MySqlOperator {

 private static final String MYSQL_URL = "jdbc:mysql://localhost:3309/ztest?allowPublicKeyRetrieval=true&useSSL=false&serverTimezone=UTC";
 private static final String MYSQL_NAME = "root";
 private static final String MYSQL_PASSWORD = "MySql@8022";
 private static Connection conn = null;
 private static Statement stt = null;
 static {
  try {
   Class.forName("com.mysql.cj.jdbc.Driver");
   conn = DriverManager.getConnection(MYSQL_URL,MYSQL_NAME,MYSQL_PASSWORD);
   stt = conn.createStatement();
  } catch (ClassNotFoundException | SQLException e) {
   e.printStackTrace();
  }
 }
 /**
  * 根据用户名和密码检查是否合法用户，
  * @param uname
  * @param pwd
  * @return
  */
 public static boolean loginChecked(String uname,String pwd){
  try {
   Statement stt = conn.createStatement();
   String sql = "select * from user where account='"+uname+"' and password = '"+pwd+"'";//这样写是有sql注入漏洞的，后面会用到
   System.out.println(sql);
   ResultSet rs = stt.executeQuery(sql);
   while (rs.next()){
    return true;
   }
  } catch ( SQLException e) {
   e.printStackTrace();
  }
  return false;
 }
 /**
  * 添加用户
  */
 public static boolean addUser(String uname,String pwd,String realName,String sex){
  Date date = new Date();
  SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:sss");
  String data_str = sdf.format(date);
  String sql = "insert into user(account,name,password,sex,add_time) values" +
    " ('"+uname+"','"+realName+"','"+pwd+"','"+sex+"','"+data_str+"')";
  System.out.println(sql);
  try {
   if(conn.isValid(2)){
    initConn();
   }
   stt.execute(sql);
   return true;
  } catch (SQLException throwable) {
   throwable.printStackTrace();
   return false;
  }
 }
 /**查询所有用户*/
 public static List<UserEntity> listAllUser(){
  String sql = "select * from user";

  ResultSet rs = null;
  ArrayList<UserEntity> all = new ArrayList<>();
  SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:sss");
  try {
   rs = stt.executeQuery(sql);
   while (rs.next()){
    UserEntity user = new UserEntity();
    user.setUname(rs.getString("account"));
    user.setPwd(rs.getString("password"));
    user.setRealName(rs.getString("name"));
    user.setSex(rs.getString("sex"));
    user.setAdd_time(sdf.format(rs.getDate("add_time")));
    user.setId(rs.getInt("id"));
    all.add(user);
   }
   System.out.println(sql);
   System.out.println("查询条数："+all.size());
   return all;
  } catch (SQLException throwable) {
   throwable.printStackTrace();
  }
  return all;
 }
 /**删除用户*/
 public static boolean delUser(int id) {
  String sql = "delete from user where id="+id;
  try {
   stt.execute(sql);
   return true;
  } catch (SQLException throwable) {
   throwable.printStackTrace();
   return false;
  }
 }
/**用于 mysql 连接断开后重连*/
 public static void initConn(){
  try {
   Class.forName("com.mysql.cj.jdbc.Driver");
   conn = DriverManager.getConnection(MYSQL_URL,MYSQL_NAME,MYSQL_PASSWORD);
   stt = conn.createStatement();
  } catch (ClassNotFoundException | SQLException e) {
   e.printStackTrace();
  }
 }
/**更新用户信息*/
 public static boolean updateUser(int id, String uname, String pwd, String realName, String sex) {
  Date date = new Date();
  SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:sss");
  String data_str = sdf.format(date);
  String sql = "update user set account='"+uname+"',password='"+pwd+"',name='"+realName+"',sex='"+sex+"',add_time='"+data_str+"' where id="+id;
  System.out.println(sql);
  try {
   if(conn.isValid(2)){
    initConn();
   }
   stt.execute(sql);
   return true;
  } catch (SQLException throwable) {
   throwable.printStackTrace();
   return false;
  }
 }
}