这一章主要是把上一章写在网页里的java 代码从网页中分离出来，放在专门的servlet类中。每一个servlet类对应一个数据库的表。
规范性问题：
1、dao包存放有关数据库的信息：BaseDao包就放数据库加载驱动和增删改和关闭资源；而其他的每一个表名对应一个相应名字的dao包，写数据库的增删改查操作；
2、servlet包专存放和网页有关的代码，把网页传来的参数进行接受，同时调用相应名字的dao类中的方法，返回到相应的页面。
3、untity包专门放对应表格的实体类
4、test包专门放测试的方法，单元测试等。
整合前面的的学生管理系统，重构一个图书管理系统，要求规范性，且网页中不在出现java代码，都放在servlet类中
在写代码前先建好相应的包，并且导入数据库的jar包，web的jar包，还有tomcat的配置，以及在数据库编辑软件navicat建好相应的数据表。
图书管理系统的运行截图：左上方两个表在数据库建好
登录界面展示：
注册界面展示：
各种功能展示：
一、代码：
BaseDao:
package com.zyl.dao;import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet;/*** @className: BaseDao* @author: Zyl* @date: 2024/12/3 16:49* @Version: 1.0* @description:*/public class BaseDao {Connection connection= null;PreparedStatement ps=null;ResultSet resultSet = null;String url = "jdbc:mysql://localhost:3306/jdbctest";String username = "root";String password = "root";String DriverName="com.mysql.jdbc.Driver";//加载驱动，获取连接，连接数据库public void connection()throws Exception{Class.forName(DriverName);connection = DriverManager.getConnection(url, username, password);}//针对增删改的方法,没有查询的功能public int edit(String sql,Object... params) {try {connection();ps = connection.prepareStatement(sql);for (int i = 0; i < params.length; i++) {ps.setObject(i + 1, params[i]);}int row = ps.executeUpdate();return row;} catch (Exception e) {throw new RuntimeException(e);} finally {closeAll();}}//关闭所有的资源public void closeAll(){try {if(resultSet!=null){resultSet.close();}if(ps!=null){ps.close();}if(connection!=null){connection.close();}}catch (Exception e){throw new RuntimeException(e);}}}
BookDao:
package com.zyl.dao;import com.zyl.untity.Book;import java.sql.PreparedStatement; import java.sql.ResultSet; import java.util.ArrayList;/*** @className: BookDao* @author: Zyl* @date: 2024/12/6 10* @Version: 1.0* @description:*/public class BookDao extends BaseDao{ //查询所有的图书public ArrayList<Book> selectAll(){ArrayList<Book> list=new ArrayList<Book>();try {connection();String sql="select * from tbl_book";ps = connection.prepareStatement(sql);resultSet = ps.executeQuery();while (resultSet.next()){int id=resultSet.getInt("id");String name=resultSet.getString("name");double price=resultSet.getDouble("price");String publisher=resultSet.getString("publisher");Book book =new Book();book.setId(id);book.setName(name);book.setPrice(price);book.setPublisher(publisher);list.add(book);}return list;} catch (Exception e) {throw new RuntimeException(e);} finally {closeAll();}}public int delete(int id){String sql = "delete from tbl_book where id=?";//d调用父类BaseDao 的edit()方法 增删改操作;;;;;;int edit = edit(sql,id);return edit;}public Book findById(int id){Book book =null;try {String sql = "select * from tbl_book where id=?";connection();ps = connection.prepareStatement(sql);ps.setInt(1,id);resultSet = ps.executeQuery();while (resultSet.next()){int id1=resultSet.getInt("id");String name=resultSet.getString("name");double price=resultSet.getDouble("price");String publisher=resultSet.getString("publisher");book=new Book(id1,name,price,publisher);}return book;} catch (Exception e) {throw new RuntimeException(e);} finally {closeAll();}}public int update(int id,String name,double price,String publisher ){String sql = "update tbl_book set name=?,price=?,publisher=?where id=?";//d调用父类BaseDao 的edit()方法 增删改操作;;;;;;int edit = edit(sql,name,price,publisher,id);return edit;}public int insert(String name,double price,String publisher ){String sql = "insert into tbl_book(name,price,publisher) values(?,?,?)";//d调用父类BaseDao 的edit()方法 增删改操作;;;;;;int edit = edit(sql,name,price,publisher);return edit;}}
UserDao:
package com.zyl.dao;import com.zyl.untity.User;/*** @className: UserDao* @author: Zyl* @date: 2024/12/6 10:15* @Version: 1.0* @description:*/public class UserDao extends BaseDao{public User login(String username, String password){User user=null;try {String sql="select * from tbl_user where username=? and password=?";connection();ps = connection.prepareStatement(sql);ps.setObject(1,username);ps.setObject(2,password);resultSet = ps.executeQuery();while(resultSet.next()){int id = resultSet.getInt("id");String username1 = resultSet.getString("username");String password1 = resultSet.getString("password");String realname = resultSet.getString("realname");int age = resultSet.getInt("age");// user=new User(username1,id,password1,realname,age);user=new User();user.setId(id);user.setUsername(username1);user.setAge(age);user.setPassword(password1);user.setRealname(realname);}} catch (Exception e) {throw new RuntimeException(e);} finally {closeAll();}return user;}public int add(String username, String password){String sql="insert into tbl_user(username,password) values(?,?)";int i=edit(sql,username,password);return i;}}
BookServlet:
package com.zyl.servlet;import com.zyl.dao.BookDao; import com.zyl.untity.Book;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; import java.io.UnsupportedEncodingException; import java.util.ArrayList;/*** @className: BookServlet* @author: Zyl* @date: 2024/12/6 10:26* @Version: 1.0* @description:*/ @WebServlet(urlPatterns = "/book") public class BookServlet extends HttpServlet {private BookDao bookDao = new BookDao();@Overrideprotected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {req.setCharacterEncoding("UTF-8");String method = req.getParameter("method");if("delete".equals(method)){delete(req,resp);}else if("getById".equals(method)){selectById(req,resp);}else if("update".equals(method)){update(req,resp);}else if("insert".equals(method)){insert(req,resp);}else{selectAll(req,resp);}}public void insert(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {//获取参数String name = req.getParameter("name");double price = Double.parseDouble(req.getParameter("price"));String publisher = req.getParameter("publisher");BookDao bookDao = new BookDao();int i = bookDao.insert(name, price, publisher);if(i>0){resp.sendRedirect("/book");}}private void selectById(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {//获取idString id = req.getParameter("id");//创建对象BookDao bookDao = new BookDao();Book b = bookDao.findById(Integer.parseInt(id));req.setAttribute("book",b);req.getRequestDispatcher("/edit.jsp").forward(req,resp);}public void selectAll(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException{BookDao bookDao = new BookDao();ArrayList<Book> books = bookDao.selectAll();req.setAttribute("books",books);req.getRequestDispatcher("/index.jsp").forward(req,resp);}public void delete(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException{String id = req.getParameter("id");//获取idBookDao bookDao = new BookDao();//创建对象int delete = bookDao.delete(Integer.parseInt(id));if(delete>0){resp.sendRedirect("/book");}}public void update(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException{//获取参数String id = req.getParameter("id");String name = req.getParameter("name");String price = req.getParameter("price");String publisher = req.getParameter("publisher");//先判断在创建对象并调用方法if(id!=null&&!id.equals("")&&name!=null&&!name.equals("")&&price!=null&&!price.equals("")&&publisher!=null&&!publisher.equals("")){BookDao b=new BookDao();int i=b.update(Integer.parseInt(id),name, Double.parseDouble(price),publisher);if(i>0){resp.sendRedirect("/book");}}} }
UserServlet:
package com.zyl.servlet;import com.zyl.dao.UserDao; import com.zyl.untity.User;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.io.UnsupportedEncodingException;/*** @className: UserServlet* @author: Zyl* @date: 2024/12/6 10:25* @Version: 1.0* @description:*/ @WebServlet(urlPatterns = "/user") public class UserServlet extends HttpServlet {private UserDao userDao=new UserDao();//对象@Overridepublic void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {req.setCharacterEncoding("utf-8");String method = req.getParameter("method");if ("login".equals(method)) {login(req, resp);} else if ("register".equals(method)) {register(req, resp);} else if ("exit".equals(method)){exit(req, resp);}}public void exit(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {HttpSession session=req.getSession();//获取session，判断是否登录，登录了就删除session，并跳转回登录页面session.removeAttribute("user");resp.sendRedirect("/login.jsp");}public void login(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {String username = req.getParameter("username");String password = req.getParameter("password");UserDao userDao = new UserDao();User user = userDao.login(username, password);if (user!= null) {//保存到session会话req.getSession().setAttribute("user", user);//跳转--成功页面【展示所有图书】resp.sendRedirect("/book");} else {//跳转到登录页面req.setAttribute("error", "<font color='red'>账号或密码错误</font>");req.getRequestDispatcher("/login.jsp").forward(req, resp);//转发跳转.必须转发跳转}}public void register(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {// 获取表单数据String username = req.getParameter("username");String password = req.getParameter("password");String confirmPassword = req.getParameter("confirmPassword");System.out.println(1222);// 初始化消息变量String message = "";String messageType = "";// 检查密码是否一致if (!password.equals(confirmPassword)) {message = "两次输入的密码不一致，请重新输入。";messageType = "error-message";} else {// 创建 UserDao 实例UserDao userDao = new UserDao();// 检查用户名和密码是否同时存在if (userDao.login(username, password) != null) {message = "该用户名和密码已被注册过。";messageType = "error-message";} else {// 调用 add 方法添加学生int result = userDao.add(username, password);if (result > 0) {message = "注册成功！";messageType = "success-message";} else {message = "注册失败，请重试。";messageType = "error-message";}}}// 将消息存储到请求属性中req.setAttribute("message", message);req.setAttribute("messageType", messageType);// 转发到 register.jsp 显示消息req.getRequestDispatcher("/register.jsp").forward(req, resp);}}
二、网页代码：
bookadd.jsp:
<%--Created by IntelliJ IDEA.User: Date: 2024/12/7Time: 16:21To 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" %> <html> <head><title>添加图书界面</title><style>body {font-family: Arial, sans-serif;background-color: #f4f4f9;display: flex;justify-content: center;align-items: center;height: 100vh;margin: 0;}.container {background-color: #fff;padding: 20px;border-radius: 8px;box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);width: 80%;max-width: 400px;text-align: center;}.container h1 {margin-bottom: 20px;}.form-group {margin-bottom: 15px;text-align: left;}.form-group label {display: block;margin-bottom: 5px;font-weight: bold;}.form-group input {width: 100%;padding: 8px;box-sizing: border-box;border: 1px solid #ccc;border-radius: 4px;}.button-container {margin-top: 20px;}.button-container button {padding: 10px 20px;border: none;border-radius: 4px;cursor: pointer;background-color: #007bff;color: white;font-size: 16px;}.button-container button:hover {background-color: #0056b3;}.error-message {color: red;margin-bottom: 15px;}.success-message {color: green;margin-bottom: 15px;}</style> </head> <body> <div class="container"><h1>添加图书界面</h1><c:if test="${sessionScope.user==null}"><c:redirect url="/login.jsp"/></c:if><form action="/book?method=insert" method="post"><div class="form-group"><label for="name">书名：</label><input type="text" id="name" name="name" placeholder="请输入书名" required/></div><div class="form-group"><label for="price">价格：</label><input type="number" id="price" name="price" placeholder="请输入价格" step="0.01" required/></div><div class="form-group"><label for="publisher">出版社：</label><input type="text" id="publisher" name="publisher" placeholder="请输入出版社" required/></div><div class="button-container"><button type="submit">添加</button></div></form> </div> </body> </html>
edit.jsp:
<%--Created by IntelliJ IDEA.User: Date: 2024/12/7Time: 15:37To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> <html> <head><title>编辑图书</title><style>body {font-family: Arial, sans-serif;background-color: #f4f4f9;display: flex;justify-content: center;align-items: center;height: 100vh;margin: 0;}.container {background-color: #fff;padding: 20px;border-radius: 8px;box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);width: 80%;max-width: 400px;text-align: center;}.container h1 {margin-bottom: 20px;}.form-group {margin-bottom: 15px;text-align: left;}.form-group label {display: block;margin-bottom: 5px;font-weight: bold;}.form-group input {width: 100%;padding: 8px;box-sizing: border-box;border: 1px solid #ccc;border-radius: 4px;}.button-container {margin-top: 20px;}.button-container button {padding: 10px 20px;border: none;border-radius: 4px;cursor: pointer;background-color: #007bff;color: white;font-size: 16px;}.button-container button:hover {background-color: #0056b3;}.error-message {color: red;margin-bottom: 15px;}.success-message {color: green;margin-bottom: 15px;}</style> </head> <body> <div class="container"><h1>编辑图书</h1><c:if test="${sessionScope.user==null}"><c:redirect url="/login.jsp"/></c:if><form action="/book?method=update" method="post"><div class="form-group"><label for="id">ID：</label><input type="text" id="id" name="id" value="${book.getId()}" readonly/></div><div class="form-group"><label for="name">书名：</label><input type="text" id="name" name="name" placeholder="请输入书名" value="${book.getName()}" required/></div><div class="form-group"><label for="price">价格：</label><input type="number" id="price" name="price" placeholder="请输入价格" value="${book.getPrice()}" step="0.01" required/></div><div class="form-group"><label for="publisher">出版社：</label><input type="text" id="publisher" name="publisher" placeholder="请输入出版社" value="${book.getPublisher()}" required/></div><div class="button-container"><button type="submit">立即修改</button></div></form> </div> </body> </html>
index.jsp:
<%@ page import="com.zyl.untity.User" %><%--Created by IntelliJ IDEA.User: ${zyl}Date: 2024/12/6Time: 10:12To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> <html> <head><title>图书首页</title><style>body {font-family: Arial, sans-serif;background-color: #f4f4f9;display: flex;justify-content: center;align-items: center;height: 100vh;margin: 0;}.container {background-color: #fff;padding: 20px;border-radius: 8px;box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);width: 80%;max-width: 800px;text-align: center;}.container h1 {margin-bottom: 20px;}.button-container {margin-bottom: 20px;}.button-container button {margin: 0 10px;padding: 10px 20px;border: none;border-radius: 4px;cursor: pointer;background-color: #007bff;color: white;font-size: 16px;}.button-container button:hover {background-color: #0056b3;}table {width: 100%;border-collapse: collapse;margin-top: 20px;}th, td {border: 1px solid #ddd;padding: 8px;text-align: left;}th {background-color: #f2f2f2;}tr:nth-child(even) {background-color: #f9f9f9;}tr:hover {background-color: #f1f1f1;}a {margin: 0 5px;text-decoration: none;color: #007bff;}a:hover {text-decoration: underline;}</style> </head> <body> <c:if test="${sessionScope.user == null}"><c:redirect url="/login.jsp"/> </c:if> <div class="container"><h1>欢迎${sessionScope.user.realname}访问图书管理系统</h1><div class="button-container"><button οnclick="location.href='/bookadd.jsp'">添加</button><button οnclick="location.href='/user?method=exit'">退出</button></div><table><tr><th>编号</th><th>姓名</th><th>价格</th><th>出版社</th><th>操作</th></tr><c:forEach items="${requestScope.books}" var="b"><tr><td>${b.id}</td><td>${b.name}</td><td>${b.price}</td><td>${b.publisher}</td><td><a οnclick="del(${b.id})">删除</a><a href="/book?method=getById&id=${b.id}">修改</a></td></tr></c:forEach></table> </div> <script>function del(id) {var b = confirm("是否删除该记录?");if (b) {location.href = "/book?method=delete&id=" + id;}} </script> </body> </html>
login.jsp:
<%--Created by IntelliJ IDEA.User: Date: 2024/12/6Time: 10:50To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head><title>登录界面</title><style>body {font-family: Arial, sans-serif;background-color: #f4f4f9;display: flex;justify-content: center;align-items: center;height: 100vh;margin: 0;}.login-container {background-color: #fff;padding: 20px;border-radius: 8px;box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);width: 300px;text-align: center;}.login-container h2 {margin-bottom: 20px;}.login-container input[type="text"],.login-container input[type="password"] {width: calc(100% - 22px);padding: 10px;margin: 10px 0;border: 1px solid #ccc;border-radius: 4px;}.login-container input[type="submit"],.login-container input[type="button"] {width: calc(100% - 22px);padding: 10px;margin: 10px 0;border: none;border-radius: 4px;cursor: pointer;background-color: #007bff;color: white;font-size: 16px;}.login-container input[type="submit"]:hover,.login-container input[type="button"]:hover {background-color: #0056b3;}.error-message {color: red;margin-bottom: 10px;}</style> </head> <body> <div class="login-container"><h2>登录界面</h2><div class="error-message">${error}</div><form action="/user?method=login" method="post"><input type="text" name="username" placeholder="账号"/><br><input type="password" name="password" placeholder="密码"/><br><input type="submit" value="立即登录"/><input type="button" value="注册" οnclick="location.href='register.jsp'"/></form> </div> </body> </html>
register.jsp:
<%--Created by IntelliJ IDEA.User: Date: 2024/12/7Time: 10:56To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> <html> <head><title>注册界面</title><style>body {font-family: Arial, sans-serif;background-color: #f4f4f9;display: flex;justify-content: center;align-items: center;height: 100vh;margin: 0;}.container {background-color: #fff;padding: 20px;border-radius: 8px;box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);width: 80%;max-width: 400px;text-align: center;}.container h1 {margin-bottom: 20px;}.form-group {margin-bottom: 15px;text-align: left;}.form-group label {display: block;margin-bottom: 5px;font-weight: bold;}.form-group input {width: 100%;padding: 8px;box-sizing: border-box;border: 1px solid #ccc;border-radius: 4px;}.button-container {margin-top: 20px;}.button-container button {padding: 10px 20px;border: none;border-radius: 4px;cursor: pointer;background-color: #007bff;color: white;font-size: 16px;}.button-container button:hover {background-color: #0056b3;}.error-message {color: red;margin-bottom: 15px;}.success-message {color: green;margin-bottom: 15px;}.login-link {margin-top: 15px;font-size: 14px;}.login-link a {color: #007bff;text-decoration: none;}.login-link a:hover {text-decoration: underline;}</style> </head> <body> <div class="container"><h1>注册界面</h1><c:if test="${not empty message}"><div class="${messageType}">${message}</div></c:if><form action="/user?method=register" method="post"><div class="form-group"><label for="username">账号：</label><input type="text" id="username" name="username" required></div><div class="form-group"><label for="password">密码：</label><input type="password" id="password" name="password" required></div><div class="form-group"><label for="confirmPassword">确认密码：</label><input type="password" id="confirmPassword" name="confirmPassword" required></div><div class="button-container"><button type="submit">注册</button></div><div class="login-link"><a href="login.jsp">已有账号，立即登录</a></div></form> </div> </body> </html>