使用idea开发javaWeb应用程序的思路(实现用户的增删改查)
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='https://www.haobala.com/css/my.css' rel='external nofollow' rel='external nofollow' > <script type='text/javascript' src='https://www.haobala.com/js/my.js'></script></head><body><div > <div > <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 > <h3 style='margin-bottom:0;'>添加用户</h3> <form action='addUser' method='post'> <input type='hidden' name='id' /> <p>登录账号: <input type='text' name='uname' /></p> <p>真实姓名: <input type='text' name='realName' /></p> <p>选择性别: <select name='sex' style='width:170px'> <option value ='男'>男</option> <option value ='女'>女</option> </select></p> <p>登录密码: <input type='password' name='pwd' /></p> <p>确认密码: <input 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='https://www.haobala.com/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 > <div > <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 > <table border='1' > <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='https://www.haobala.com/bcjs/del?id=<%=user.getId()%> ' rel='external nofollow' >删除</a> <a href='https://www.haobala.com/bcjs/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='https://www.haobala.com/bcjs/user/add.html' rel='external nofollow' ;}function toSearchUser(){ window.location.href='https://www.haobala.com/bcjs/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; } }}7、 运行效果
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