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预备：

数据库

本次作业选择的数据库为MYSQL，采用的数据库管理工具为Navicat Premium12。MYSQL下载地址为https://dev.mysql.com/downloads/mysql/

使用Navicat连接数据库。

1.首先打开Navicat图形化管理界面，点击连接，若在本地开发，主机和端口没有占用的话直接默认的就可以。用户名和密码均为root，之后便可建立与数据库的链接，后面的数据库操作均可通过Navicat控制完成。

gKyG8g.png

使用Navicat连接MYSQL数据库界面

2.设置Tomcat服务器，Java链接数据库最常用的就是通过jar包导入之后直接使用封装好的方法来实现的，安装JDBC驱动即可。本人使用的Tomcat版本为9.0.24，其中JDBC驱动为mysql-connector-java-5.1.48-bin.jar。将该jar包拷贝到服务器的lib文件夹中。重新启动服务器，能够成功启动即可。

3.最后通过eclipse建立JSP文件来测试能否实现数据库的连接。

测试内容如下：

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<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ page import="java.sql.*"%>

<html>
<head>
<title>页面输出数据库中制定数据表数据</title>
</head>
<body>

 <%  
        try {  
            Class.forName("com.mysql.jdbc.Driver");  //驱动程序名
            String url = "jdbc:mysql://localhost:3306/test"; //数据库名
            String username = "root";  //数据库用户名
            String password = "root";  //数据库用户密码
            Connection conn = DriverManager.getConnection(url, username, password);  //连接状态

            if(conn != null){  
                out.print("数据库连接成功！");  
                out.print("<br />");            
                Statement stmt = null;  
                ResultSet rs = null;  
                String sql = "SELECT *FROM students;";  //查询语句
                stmt = conn.createStatement();  
                rs = stmt.executeQuery(sql);  
                out.print("查询结果：");  
                out.print("<br />");  
                out.println("姓名"+"  "+"电话 ");  
                out.print("<br />");  
                while (rs.next()) {  
                 out.println(rs.getString("name")+"   &nbsp  "+rs.getString("tel")+"  &nbsp "); //将查询结果输出
                 out.print("<br />");  
            }  
            }
            else{  
                out.print("连接失败！");  
            }  
        }catch (Exception e) {        
            out.print("数据库连接异常！");  
        }  
%>   
</body>
</html>
gKyHXX.png

使用Navicat看到的数据表中的数据

gKy52G.png

在网页端看到的数据表中的数据

二者内容一致说明数据库连接成功！

开始项目：

开发工具为Eclipse Java Photon。做好所有的预备工作后，即可开始开发。

开发时应注意代码的复用性以及可维护性。具体表现在：

1.所有代码分好类别存储，便于维护和修改。

2.涉及到数值问题的都用符号求得后表示，若绝对写死，一旦数据库中数据数量发生变化，项目在运行过程中容易出错。

3.数据库中数据表的设计应尽量减少冗余，在进行数据的操作时尽量使用多表查询，减轻服务器以及数据库的负担。

登录注册页的实现

需要注意的地方：

1.“永远不要相信用户的输入”，并非所有的用户输入都符合系统需求。在注册时添加确认密码一项使得用户能有缓冲时间。

2.输入时得情况判断：（1）用户是否输入完整。（2）输入完整时账号密码都正确、输入的账号不存在、输入的账号存在密码错误

需要注意的细节：在安全角度来讲，一旦用户输入密码错误不要单纯的给用户提示“密码错误”，最好提示“账号或密码错误”，在大型系统中防止黑客的暴力破解。

3.登录整体使用MVC的设计模式，通过JSP前端页面产生交互信息，交互信息与bean和servlet产生交互效果。

bean

useInfo.java:

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package bean;

import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Connection;

public class userInfo {
	String account;
	String password;

	public String getAccount() {
		return account;
	}

	public void setAccount(String account) {
		this.account = account;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

	/* 链接数据库，将信息存入 */

	public boolean storeMsg(userInfo u) throws SQLException, ClassNotFoundException {
		Class.forName("com.mysql.jdbc.Driver"); // 驱动程序名
		String url = "jdbc:mysql://localhost:3306/test"; // 数据库名
		String username = "root"; // 数据库用户名
		String password = "root"; // 数据库用户密码
		Connection conn = DriverManager.getConnection(url, username, password); // 连接状态

		String acc = u.getAccount();
		String pass = u.getPassword();
		
		String sql_check = "select * from user where account=?";

		PreparedStatement ps_check = conn.prepareStatement(sql_check );
		ps_check.setString(1, acc);
		/* ps.setString(2, pass); */
		ResultSet rs = null;
		rs = ps_check.executeQuery();
		if (!rs.next()) {
			//说明不存在该账号
			String sql = "insert into  user(account,password) values (?,?)";

			PreparedStatement ps = conn.prepareStatement(sql);
			ps.setString(1, acc);
			ps.setString(2, pass);
			int result = 0;
			result = ps.executeUpdate();

			/* 关闭数据库 */
			ps.close();
			conn.close();

			if (result > 0) {
				return true;
			} else {
				return false;
			}
		}else {
			/* 关闭数据库 */
			ps_check.close();
			conn.close();
			return false;
		}
		
		
	}

	/* 数据的检索 */
	public boolean checkMsg(userInfo u) throws SQLException, ClassNotFoundException {
		Class.forName("com.mysql.jdbc.Driver"); // 驱动程序名
		String url = "jdbc:mysql://localhost:3306/test"; // 数据库名
		String username = "root"; // 数据库用户名
		String password = "root"; // 数据库用户密码
		Connection conn = DriverManager.getConnection(url, username, password); // 连接状态

		ResultSet rs = null;

		String acc = u.getAccount();
		/* String pass = u.getPassword(); */
		String sql = "select * from user where account=?";

		PreparedStatement ps = conn.prepareStatement(sql);
		ps.setString(1, acc);
		/* ps.setString(2, pass); */

		rs = ps.executeQuery();
		if (rs.next()) {
			u.setAccount(rs.getString(2));
			u.setPassword(rs.getString(3));
			/* 关闭数据库 */
			ps.close();
			conn.close();
			return true;
		} else {
			/* 关闭数据库 */
			ps.close();
			conn.close();
			return false;
		}

	}
}

login.jsp:

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<%@ page contentType="text/html;charset=UTF-8" language="java"%>
<html>
<head>
<title>登录</title>
<link rel="stylesheet" href="css/login.css">
<link rel="icon" href="img/headicon.png">
</head>
<body>
	<div class="main">
		<h1>登录</h1>
		<form action="login" method="post">
			<p>账号</p>
			<input type="text" name="account" />
			<p>密码</p>
			<input type="password" name="password" />
            <input type="submit" value="提交"> 
            <a href="register.jsp"> 
               <input type="button" value="注册">
			</a>
		</form>
	</div>
	<%
		request.setCharacterEncoding("utf-8");
		String account = request.getParameter("account");
		String password = request.getParameter("password");

		if (account == null) {
			account = "";
		}
		if (password == null) {
			password = "";
		}
	%>
</body>
</html>

login.java:

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package servlet;

import java.io.IOException;
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 javax.servlet.http.HttpSession;

import bean.userInfo;

/**
 * Servlet implementation class login
 */
@WebServlet("/login")
public class login extends HttpServlet {
	private static final long serialVersionUID = 1L;

	/**
	 * @see HttpServlet#HttpServlet()
	 */
	public login() {
		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
		/* 将得到的与数据库中进行比对，成功即可进入 */
		request.setCharacterEncoding("utf-8");
		HttpSession session = request.getSession();
		//得到登陆界面输入的账号密码
		String account = request.getParameter("account");
		String password = request.getParameter("password");
		
		//检测是否数据都输入完整
		if (account.equals("") || password.equals("")) {
			request.setCharacterEncoding("gb2312");
			// 在这里使用jsp:forward会使得css作用不上
			session.setAttribute("msg", "请将所有信息填写完整");
			response.sendRedirect("error/error.jsp");
		} else {
			/* 进行数据库中数据的判定 */
			
			//将账号和密码赋值到bean中
			userInfo u = new userInfo();
			u.setAccount(account);
			u.setPassword(password);

			try {
				
				//调用bean中方法检测是否和数据库中存在的数据相同	
				boolean data = u.checkMsg(u);
				
				//检测状态：1账号密码正确时、2.账号不存在时、3.二者有一个输入错误时
				
				if (data) {
					if (account.equals(u.getAccount()) && password.equals(u.getPassword())) {
						// 此时登录成功，在session中存入此时账号信息，供后面页面使用
						session.setAttribute("account", account);
						response.sendRedirect("main/main.jsp");
					} else {

						/*
						 * String a=u.getAccount(); String b=u.getPassword();
						 * 
						 * String c=a+"----"+b; session.setAttribute("msg", c);
						 */
						session.setAttribute("msg", "账号或密码错误，请重新输入");
						response.sendRedirect("error/error.jsp");
					}
				} else {
					session.setAttribute("msg", "该账号不存在");
					response.sendRedirect("error/error.jsp");
				}
			} 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
		doGet(request, response);
	}

}

register.jsp:

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<%@ page contentType="text/html;charset=UTF-8" language="java"%>
<html>
<head>
<title>注册</title>
<link rel="stylesheet" href="css/login.css">
<style>
body {
	background: url("img/B3.jpg");
	background-size: cover;
}
</style>
</head>
<body>
	<div class="main">
		<h1>注册</h1>
		<form action="register" method="post">
			<p>账号</p>
			<input type="text" name="account" />
			<p>密码</p>
			<input type="password" name="password" />
			<p>确认密码</p>
			<input type="password" name="checkPass" /> 
            <input type="submit" value="确定">
		</form>
	</div>
	<%
		request.setCharacterEncoding("utf-8");
		String account = request.getParameter("account");
		String password = request.getParameter("password");
		String checkPass = request.getParameter("checkPass");
		if (account == null || password == null || checkPass == null) {
			account = "";
			password = "";
			checkPass = "";
		}
	%>
</body>
</html>

register.java:

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package servlet;

import java.io.IOException;
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 javax.servlet.http.HttpSession;

import bean.userInfo;

/**
 * Servlet implementation class register
 */
@WebServlet("/register")
public class register extends HttpServlet {
	private static final long serialVersionUID = 1L;

	/**
	 * @see HttpServlet#HttpServlet()
	 */
	public register() {
		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

		HttpSession session = request.getSession();
		request.setCharacterEncoding("utf-8");
		String account = request.getParameter("account");
		String password = request.getParameter("password");
		String checkPass = request.getParameter("checkPass");
		if (account.equals("") || password.equals("") || checkPass.equals("")) {
			session.setAttribute("msg", "请将所有信息输入完整_");
			response.sendRedirect("error/error.jsp");
		} else {
			if (!password.equals(checkPass)) {
				session.setAttribute("msg", "两次输入的密码不一致，请重新输入_");
				response.sendRedirect("error/error.jsp");
			} else {

				/* 将账号、信息存入数据库中 */
				userInfo u = new userInfo();
				u.setAccount(account);
				u.setPassword(password);

				try {
					if (u.storeMsg(u)) {
						session.setAttribute("account", account+"");
						session.setAttribute("password", password+"");
						response.sendRedirect("success/regSuc.jsp");
					}else {
						
						//说明有重复的账号
						session.setAttribute("msg", "该账号已被注册");
						response.sendRedirect("error/error.jsp");
					}
				} 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
		doGet(request, response);
	}

}

页面截图：

gK59qc.png

登录页

gK5LxK.png

注册页

### 主页面的实现

主页面中展示的为相关编程语言信息，里面的按钮为系统中最重要的可交互元素，其中数据全部来源于数据库，这样通过遍历在数据库中读数据可大大减少前端代码量，减轻前端开发时的负担。

main.jsp:

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<%@ page language="java" contentType="text/html; charset=utf-8"
	pageEncoding="utf-8"%>
<%@ page import="java.sql.*"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>主页</title>
<link rel="stylesheet" href="../css/main.css">
<link rel="icon" href="../img/headicon.png">
</head>
<body>
	<div class="head">
		<span>computer's language</span> 
		<a href="../person/person.jsp"><span class="head_peo">欢迎你,<%=session.getAttribute("account")%></span></a>
	<a href="../person/mygoods.jsp"><span class="head_peo">个人购物车</span></a>
	</div>
	<div class="container">
		<%
			try {
				Class.forName("com.mysql.jdbc.Driver"); //驱动程序名
				String url = "jdbc:mysql://localhost:3306/test"; //数据库名
				String username = "root"; //数据库用户名
				String password = "root"; //数据库用户密码
				Connection conn = DriverManager.getConnection(url, username, password); //连接状态

				if (conn != null) {
					Statement stmt = null;
					ResultSet rs = null;
					String sql = "SELECT *FROM content;"; //查询语句
					stmt = conn.createStatement();
					rs = stmt.executeQuery(sql);

					int all = 0;
					while (rs.next()) {
						all++;
						session.setAttribute("num", all + "");
		%>
		<div class="item">
			<div class="img">
				<img src=<%=rs.getString("img")%> alt="python">
			</div>
			<div class="font">
				<p><%=rs.getString("language")%></p>
				<p class="describe"><%=rs.getString("des")%></p>
			</div>
			<div class="button">
			
			<!-- 通过点击不同的按钮跳到指定相关的购物界面 -->
			<form action="../goshop" method="post">
				<input type="submit" name=<%=rs.getString("id") + "_learn"%>
					value="学习" class="more">
					</form>
				<form action="../getContent" method="post">
					<input type="submit" name=<%=rs.getString("id") + "_like"%>
						value="喜欢" class="like">
				</form>
				<a href=<%=rs.getString("url")%> target="_blank">
					<button class="official">官网</button>
				</a>
			</div>
		</div>
		<%
			}
				} else {
					out.print("连接失败！");
				}
			} catch (Exception e) {
				out.print("数据库连接异常！");
			}
		%>
	</div>
</body>
</html>

goshop.java:

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package servlet;

import java.io.IOException;

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;

/**
 * Servlet implementation class goshop
 */
@WebServlet("/goshop")
public class goshop extends HttpServlet {
	private static final long serialVersionUID = 1L;

	/**
	 * @see HttpServlet#HttpServlet()
	 */
	public goshop() {
		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
		
		/*主要起到存储session信息的作用*/
		request.setCharacterEncoding("utf-8");
		response.setCharacterEncoding("utf-8");
		response.setContentType("text/html;chartset=utf-8");
		HttpSession session = request.getSession();
		// 得到语言的总条数，
		String n = (String) session.getAttribute("num");
		int num = Integer.parseInt(n);
		//因为数据库中语言的id是从0开始的，所以一种值 对应一种语言
		for (int i = 0; i < num; i++) {
			if (request.getParameter(i + "_learn") != null) {
				// 说明点击了对应语言的学习，将该信息存入session中方便shop页的使用
				session.setAttribute("learn", i + "");
				// 重定向
				response.sendRedirect("shop/shop.jsp");
			}
		}

	}

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

getContent.java:

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package servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

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;

/**
 * Servlet implementation class getContent
 */
@WebServlet("/getContent")
public class getContent extends HttpServlet {
	private static final long serialVersionUID = 1L;

	/**
	 * @see HttpServlet#HttpServlet()
	 */
	public getContent() {
		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
		/*
		 * response.getWriter().append("Served at: ").append(request.getContextPath());
		 */
		request.setCharacterEncoding("utf-8");
		response.setCharacterEncoding("utf-8");
		response.setContentType("text/html;chartset=utf-8");
		
		//得到session中存在的账号信息
		HttpSession session = request.getSession();
		PrintWriter out = response.getWriter();
		try {
			Class.forName("com.mysql.jdbc.Driver");
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} // 驱动程序名
		String url = "jdbc:mysql://localhost:3306/test"; // 数据库名
		String username = "root"; // 数据库用户名
		String password = "root"; // 数据库用户密码
		try {
			Connection conn = DriverManager.getConnection(url, username, password);

			Statement stmt = null;
			ResultSet rs = null;

			String sql = "insert into  user_like(account,language_id) values (?,?)";
			String acc = (String) session.getAttribute("account");
			PreparedStatement ps = conn.prepareStatement(sql);
			ps.setString(1, acc);

			// 得到数据总条数
			String n = (String) session.getAttribute("num");
			int num = Integer.parseInt(n);
			// 用于检测是否插入成功
			int result = 0;
			for (int i = 0; i < num; i++) {
				if (request.getParameter(i + "_like") != null) {

					// 首先检测是否已存在改记录
					String test_sql = "select * from user_like where account="+acc+" and language_id="+i;
					 stmt = conn.createStatement();  
		                rs = stmt.executeQuery(test_sql);  
					
					if (rs.next()) {
						// 说明该纪录已存在
						session.setAttribute("msg", "你已点击了喜欢");
						// 重定向
						response.sendRedirect("error/showMsg.jsp");

					} else {
						ps.setInt(2, i);
						result = ps.executeUpdate();
						ps.close();
						conn.close();
						if (result > 0) {
							out.print("插入成功");
							out.print(num);
							result = 0;
							// 重定向
							response.sendRedirect("success/insertSuc.jsp");
						} else {
							out.print("插入失败");
						}
					}

				}
			}

		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} // 连接状态

	}

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

主页面截图：

gK82nt.png

主页

个人页面的实现

个人页面中主要展示用户喜欢的编程语言，在这个页面可进行已保存数据的删除，数据全部来自数据库。

该页中的用户信息来自session的存储，（这种方式并不安全，如果浏览器禁掉cookie使用，那么将无法产生该有的作用，我这只是为了使得项目中能够使用到session知识点）

person.jsp:

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<%@ page language="java" contentType="text/html; charset=utf-8"
	pageEncoding="utf-8"%>
<%@ page import="java.sql.*"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>个人页面</title>
<link rel="stylesheet" href="../css/person.css">
</head>
<body>
	<div class="head">
		<span>个人页面</span> <a href="../main/main.jsp"><span
			class="head_peo">主页面</span></a>
	</div>
	<div class="container">

		<%
			//获得当前的账号
			session.getAttribute("account");
			//链接数据库获取当前用户的语言喜欢信息
			try {
				Class.forName("com.mysql.jdbc.Driver"); //驱动程序名
				String url = "jdbc:mysql://localhost:3306/test"; //数据库名
				String username = "root"; //数据库用户名
				String password = "root"; //数据库用户密码
				Connection conn = DriverManager.getConnection(url, username, password); //连接状态

				if (conn != null) {
					/*    out.print("数据库连接成功！");  
					   out.print("<br />");     */
					Statement stmt = null;
					ResultSet rs = null;
					//操作前已去除重复记录
					String sql = "SELECT user_like.id, language,language_id,des,url,img FROM user_like,content where user_like.language_id=content.id and account="
							+ (String) session.getAttribute("account"); //查询语句
					stmt = conn.createStatement();
					rs = stmt.executeQuery(sql);

					while (rs.next()) {
		%>
		<div class="item">
			<div class="img">
				<img src=<%=rs.getString("img")%>>
			</div>
			<div class="font">
				<p><%=rs.getString("language")%></p>
			</div>
			<div class="button">
				<form action="../deleteLike" method="post">
					<input type="submit"
						name=<%=rs.getString("language_id") + "_unlike"%> value="取消喜欢"
						class="like">
				</form>
				<a href=<%=rs.getString("url")%> target="_blank">
					<button class="official">官网</button>
				</a>
			</div>
		</div>
		<%
			/*  out.println(rs.getString("user_like.id") ); //将查询结果输出
													out.print("<br />");  */
					}
				} else {
					out.print("连接失败！");
				}
			} catch (Exception e) {
				out.print("数据库连接异常！");
			}
		%>
		
	</div>

</body>
</html>

deleteLike.java:

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package servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;

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 javax.servlet.http.HttpSession;

/**
 * Servlet implementation class deleteLike
 */
@WebServlet("/deleteLike")
public class deleteLike extends HttpServlet {
	private static final long serialVersionUID = 1L;

	/**
	 * @see HttpServlet#HttpServlet()
	 */
	public deleteLike() {
		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
		request.setCharacterEncoding("utf-8");
		response.setCharacterEncoding("utf-8");
		response.setContentType("text/html;chartset=utf-8");
		HttpSession session = request.getSession();
		PrintWriter out = response.getWriter();
		try {
			Class.forName("com.mysql.jdbc.Driver");
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} // 驱动程序名
		String url = "jdbc:mysql://localhost:3306/test"; // 数据库名
		String username = "root"; // 数据库用户名
		String password = "root"; // 数据库用户密码
		try {
			Connection conn = DriverManager.getConnection(url, username, password);

			String sql = "delete from user_like where account=? and language_id=?";
			String acc = (String) session.getAttribute("account");
			PreparedStatement ps = conn.prepareStatement(sql);
			ps.setString(1, acc);

			// 得到数据总条数
			String n = (String) session.getAttribute("num");
			int num = Integer.parseInt(n);
			// 用于检测是否成功
			int result = 0;
			for (int i = 0; i < num; i++) {
				if (request.getParameter(i + "_unlike") != null) {

					// 此处不用检测是否已存在改记录
					ps.setInt(2, i);
					result = ps.executeUpdate();
					ps.close();
					conn.close();
					if (result > 0) {
						/*out.print("删除");
						out.print(num);*/
						result = 0;
						// 重定向
						response.sendRedirect("success/deleteSuc.jsp");
					} else {
						out.print("删除失败");
					}
				}

			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} // 连接状态
	}

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

个人页面截图：

gK8kZJ.png

个人页面

学习资料页面的实现

用户在主页面点击不同语言的学习按钮，会显示不同的学习资料，主要使用SQL查询来实现，通过唯一的主键来确定。并且支持学习资料的购买个数选择。

shop.jsp:

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<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<%@ page import="java.sql.*"%>

<html>
<head>
<title>学习资料</title>
<link rel="stylesheet" href="../css/shop.css">
</head>
<body>
	<div class="head">
		<span>学习资料</span> <a href="../main/main.jsp"><span
			class="head_peo">回到主页</span></a>
	</div>
	<div class="container">
		<%
			/* 开始读取对应语言的工具书 */

			//链接数据库获取当前用户的语言喜欢信息
			try {
				Class.forName("com.mysql.jdbc.Driver"); //驱动程序名
				String url = "jdbc:mysql://localhost:3306/test"; //数据库名
				String username = "root"; //数据库用户名
				String password = "root"; //数据库用户密码
				Connection conn = DriverManager.getConnection(url, username, password); //连接状态

				if (conn != null) {
					/*    out.print("数据库连接成功！");  
					   out.print("<br />");     */
					Statement stmt = null;
					ResultSet rs = null;
					//查询操作
					
					//session中记录了该种语言的id值，id是唯一的
					String sql = "SELECT id,bprice, bdes,img,lid FROM goods where lid in (select id from content where id="
							+ (String) session.getAttribute("learn") + ")"; //查询语句
					stmt = conn.createStatement();
					rs = stmt.executeQuery(sql);

					while (rs.next()) {
		%>

		<div class="item">
			<img src=<%=rs.getString("img")%> alt="">
			<hr style="height: 2px; border: none; border-top: 5px ridge black;" />
			<div class="price">
				￥<%=rs.getFloat("bprice")%>
			</div>
			<div class="describe">
				<%=rs.getString("bdes")%>
			</div>
			<div class="operation">
				
				<form action="../buyGoods" method="post">
				<span>购买数量：</span> 
				<select name="buyNum">
					<option value="1">1</option>
					<option value="2">2</option>
					<option value="3">3</option>
					<option value="4">4</option>
					<option value="5">5</option>
				</select>
				 <input type="submit" value="购买" name=<%=rs.getString("id") +"_buy"%>>
				 </form>
			</div>
		</div>

		<%
			/*  out.println(rs.getString("user_like.id") ); //将查询结果输出
																			out.print("<br />");  */
					}
				} else {
					out.print("连接失败！");
				}
			} catch (Exception e) {
				out.print("数据库连接异常！");
			}
		%>
	</div>
</body>
</html>

buyGoods.java:

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package servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;

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 javax.servlet.http.HttpSession;*/

/**
 * Servlet implementation class buyGoods
 */
@WebServlet("/buyGoods")
public class buyGoods extends HttpServlet {
	private static final long serialVersionUID = 1L;

	/**
	 * @see HttpServlet#HttpServlet()
	 */
	public buyGoods() {
		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
		// 此页处理用户购买的物品，并将购买记录存入数据库

		// 获取数据库中所有的物品
		request.setCharacterEncoding("utf-8");
		response.setCharacterEncoding("utf-8");
		response.setContentType("text/html;chartset=utf-8");
		HttpSession session = request.getSession();
		PrintWriter out = response.getWriter();
		try {
			Class.forName("com.mysql.jdbc.Driver"); // 驱动程序名
			String url = "jdbc:mysql://localhost:3306/test"; // 数据库名
			String username = "root"; // 数据库用户名
			String password = "root"; // 数据库用户密码
			Connection conn = DriverManager.getConnection(url, username, password); // 连接状态

			if (conn != null) {
				Statement stmt = null;
				ResultSet rs = null;
				String sql = "SELECT * FROM goods;"; // 查询语句
				stmt = conn.createStatement();
				rs = stmt.executeQuery(sql);
				// 获取书籍的数据总条数
				int count = 0;
				while (rs.next()) {
					count++;
				}
				
				
				out.print(count);
				// 得到点击的按钮位置，从0开始是因为数据表中的id是从0开始的
				for (int i = 0; i < count; i++) {
					if (request.getParameter(i + "_buy") != null) {
						// 获取购买数量和账号信息，之后将这条数据存入数据表中

						String acc = (String) session.getAttribute("account");
						String num = request.getParameter("buyNum");
						int number=Integer.parseInt(num);
						
						/*out.print(account);
						out.print("<br/>");
						out.print(num);
						
						//得到该商品在数据表中的id
						out.print("-----"+i);*/
						int result=0;
						String sql_buy = "insert into  buy(account,gid,num) values (?,?,?)";
						PreparedStatement ps = conn.prepareStatement(sql_buy);
						ps.setString(1, acc);
						ps.setInt(2, i);
						ps.setInt(3, number);
						result = ps.executeUpdate();
						ps.close();
						conn.close();
						if (result > 0) {
							out.print("插入成功");
							out.print(num);
							result = 0;
							// 重定向
							response.sendRedirect("success/insertSuc1.jsp");
						} else {
							out.print("插入失败");
						}
					}
				}

			} else {
				out.print("连接失败！");
			}
		} catch (Exception e) {
			out.print("数据库连接异常！");
		}

	}

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

相关截图：

gK8t50.png

学习资料页

gK8ZX1.png

购买成功

购物车页面的实现

购物车中主要为用户添加的相关学习资料信息，在这个页面用户可取消相关资料的购买，同时也可以对已经加入购物车的数据进行数量的修改，之后页面中重新显示所有的价钱。

mygoods.jsp:

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<%@ page language="java" contentType="text/html; charset=utf-8"
	pageEncoding="utf-8"%>
<%@ page import="java.sql.*"%>
<%@ page import="java.util.ArrayList"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>购物车</title>
<link rel="stylesheet" href="../css/shop.css">
</head>

<%
	float money = 0;
%>
<body>
	<div class="head" style="margin-bottom: 0">
		<span>购物车</span> <a href="../main/main.jsp"><span class="head_peo">主页面</span></a>
	</div>
	<div class="container">

		<%
			//获得当前的账号
			session.getAttribute("account");
			//链接数据库获取当前用户的语言喜欢信息
			try {
				Class.forName("com.mysql.jdbc.Driver"); //驱动程序名
				String url = "jdbc:mysql://localhost:3306/test"; //数据库名
				String username = "root"; //数据库用户名
				String password = "root"; //数据库用户密码
				Connection conn = DriverManager.getConnection(url, username, password); //连接状态

				if (conn != null) {
					/*    out.print("数据库连接成功！");  
					   out.print("<br />");     */
					Statement stmt = null;
					ResultSet rs = null;
					//操作前已去除重复记录
					String sql = "select * from goods,buy where buy.gid=goods.id and account="
							+ (String) session.getAttribute("account"); //查询语句
					stmt = conn.createStatement();
					rs = stmt.executeQuery(sql);
					ArrayList<Integer> List = new ArrayList<Integer>();
					while (rs.next()) {
						money += rs.getInt("num") * rs.getFloat("bprice");
						List.add(rs.getInt("buy.id"));
						session.setAttribute("list", List);
		%>
		<div class="item" style="margin-top: 40px;height:400px;">
			<img src=<%=rs.getString("img")%> alt="">
			<hr style="height: 2px; border: none; border-top: 5px ridge black;" />
			<div class="price">
				￥<%=rs.getFloat("bprice")%>
			</div>
			<div class="describe">
				<%=rs.getString("bdes")%>
			</div>
			<div class="operation">

				<form action="../deleteBuy" method="post">
					<span>购买数量：<%=rs.getInt("num")%></span> <input type="submit"
						value="取消购买" name=<%=rs.getInt("buy.id") + "_notBuy"%>>
				</form>
			</div>
			<hr style="height: 2px; border: none; border-top: 2px ridge black;margin-top:20px;" />
			<div class="operation">

				<form action="../changeBuyNum" method="post">
					<span>修改购买数量：</span>
					<select name="buyNum">
					<option value="1">1</option>
					<option value="2">2</option>
					<option value="3">3</option>
					<option value="4">4</option>
					<option value="5">5</option>
				</select>
					 <input type="submit" value="确定" name=<%=rs.getInt("buy.id") + "_changeBuy"%> style="background:green;">
				</form>
			</div>
		</div>
		<%
			/*  out.println(rs.getString("user_like.id") ); //将查询结果输出
																out.print("<br />");  */
					}
				} else {
					out.print("连接失败！");
				}
			} catch (Exception e) {
				out.print("数据库连接异常！");
			}
		%>

	</div>
	<div class="all">
		一共<%=money%>元
	</div>
</body>
</html>

deleteBuy.java:

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package servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.ArrayList;

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;

/**
 * Servlet implementation class deleteBuy
 */
@WebServlet("/deleteBuy")
public class deleteBuy extends HttpServlet {
	private static final long serialVersionUID = 1L;

	/**
	 * @see HttpServlet#HttpServlet()
	 */
	public deleteBuy() {
		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
		// 该页面主要用于已购买商品的删除
		request.setCharacterEncoding("utf-8");
		response.setCharacterEncoding("utf-8");
		response.setContentType("text/html;chartset=utf-8");
		HttpSession session = request.getSession();
		PrintWriter out = response.getWriter();
		try {
			Class.forName("com.mysql.jdbc.Driver");
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} // 驱动程序名
		String url = "jdbc:mysql://localhost:3306/test"; // 数据库名
		String username = "root"; // 数据库用户名
		String password = "root"; // 数据库用户密码
		try {
			Connection conn = DriverManager.getConnection(url, username, password);
			
			//此时的id为buy表中的id，唯一
			String sql = "delete from buy where id=?";
			/* String acc = (String) session.getAttribute("account"); */
			PreparedStatement ps = conn.prepareStatement(sql);
			/* ps.setString(1, acc); */

			// 得到数据总条数
			/*
			 * String n = (String) session.getAttribute("num"); int num =
			 * Integer.parseInt(n);
			 */

			ArrayList<Integer> num = (ArrayList<Integer>) session.getAttribute("list");
			// 用于检测是否成功
			int result = 0;
			// 检测是否存入arraylist
			out.print(num);
			for (int i = 0; i < num.size(); i++) {
				if (request.getParameter(num.get(i) + "_notBuy") != null) {

					/* out.print(num.get(i)); */

					// 此处不用检测是否已存在改记录
					ps.setInt(1, num.get(i));
					result = ps.executeUpdate();
					ps.close();
					conn.close();
					if (result > 0) {
						out.print("删除");
						out.print(num);
						result = 0;
						// 重定向
						response.sendRedirect("success/notBuySuc.jsp");
					} else {
						out.print("删除失败");
					}
				}

			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} // 连接状态

	}

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

changeBuyNum.java:

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package servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;

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;

/**
 * Servlet implementation class changeBuyNum
 */
@WebServlet("/changeBuyNum")
public class changeBuyNum extends HttpServlet {
	private static final long serialVersionUID = 1L;

	/**
	 * @see HttpServlet#HttpServlet()
	 */
	public changeBuyNum() {
		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
		// 修改商品的购买数量
		request.setCharacterEncoding("utf-8");
		response.setCharacterEncoding("utf-8");
		response.setContentType("text/html;chartset=utf-8");
		HttpSession session = request.getSession();
		PrintWriter out = response.getWriter();
		try {
			Class.forName("com.mysql.jdbc.Driver");
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} // 驱动程序名
		String url = "jdbc:mysql://localhost:3306/test"; // 数据库名
		String username = "root"; // 数据库用户名
		String password = "root"; // 数据库用户密码
		try {
			Connection conn = DriverManager.getConnection(url, username, password);

			String sql = "update buy set num=? where id=?";
			PreparedStatement ps = conn.prepareStatement(sql);
			ArrayList<Integer> num = (ArrayList<Integer>) session.getAttribute("list");
			// 用于检测是否成功
			int result = 0;
			// 检测是否存入arraylist
			out.print(num);
			for (int i = 0; i < num.size(); i++) {
				if (request.getParameter(num.get(i) + "_changeBuy") != null) {

					/* out.print(num.get(i)); */
					// 得到修改后的购买数量
					String number = request.getParameter("buyNum");
					int sum = Integer.parseInt(number);

					ps.setInt(1, sum);
					ps.setInt(2, num.get(i));
					result = ps.executeUpdate();
					ps.close();
					conn.close();
					if (result > 0) {
						out.print("修改");
						out.print(num);
						result = 0;
						// 重定向
						response.sendRedirect("success/changeNumSuc.jsp");
					} else {
						out.print("修改失败");
					}
				}

			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} // 连接状态

	}

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

相关截图：

gK8env.png

购物车

数据库表的设计： 设计理念为尽可能地减少数据表地冗余性，增加相关性
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