基于MVC模式的数据库综合练习

一.准备

没什么好说的，直接上代码。。。。

下面是web.xml

  <servlet>

  	<servlet-name>list_user</servlet-name>

  	<servlet-class>servlet.UserList</servlet-class>

  </servlet>

  <display-name>servlet_2</display-name>

  <servlet-mapping>

  	<servlet-name>list_user</servlet-name>

  	<url-pattern>/userList</url-pattern>

  </servlet-mapping>

文档结构如下

二.代码实现

package bean;

import java.util.List;

public class PageBean {

	private int rowCount;

	private int pageSize;

	private int pageCount;

	private int pageNum;

	private List contents;

	//下面是get、set方法

}

package bean;

import java.util.Date;

public class User {

	private int id;

	private String username;

	private String password;

	private Date birthday;

	//下面是get/set

}

package dao;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

public class DbTool {

	public static Connection getConnection(){

		Connection conn = null;

		try{

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

			String url = "jdbc:mysql://127.0.0.1/db_user";

			String uid = "root";

			String pid = "root";

			conn = DriverManager.getConnection(url,uid,pid);

		}catch(Exception exp){

			exp.printStackTrace();

		}

		return conn;

	}

	public static void closeConnection(Connection conn){

		try {

			if(null != conn && !conn.isClosed()){

				conn.close();

			}

		} catch (SQLException e) {

			e.printStackTrace();

		}

	}

	public static Object getOneResult(String cmd){

		Object o = null;

		Connection conn = getConnection();

		try {

			Statement st = conn.createStatement();

			ResultSet rs = st.executeQuery(cmd);

			if(rs.next()){

				o = rs.getObject(1);

			}

			rs.close();

		} catch (SQLException e) {

			e.printStackTrace();

		}

		closeConnection(conn);

		return o;

	}

	public static int execute(String cmd){

		Connection conn = getConnection();

		int result = 0;

		try {

			Statement st = conn.createStatement();

			result = st.executeUpdate(cmd);

		} catch (SQLException e) {

			e.printStackTrace();

		}

		closeConnection(conn);

		return result;

	}

}

package dao;

import java.sql.Connection;

import java.sql.ResultSet;

import java.sql.Statement;

import java.text.SimpleDateFormat;

import java.util.ArrayList;

import java.util.List;

import bean.PageBean;

import bean.User;

public class UserDao {

	public static void add(User u){

		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");

		String cmd = "insert into t_user (username,password,birthday) values('"+

				u.getUsername()+"','"+

				u.getPassword()+"','"+

				sdf.format(u.getBirthday())+"')";

		DbTool.execute(cmd);

	}

	public static void delete(int id){

		String cmd = "delete from t_user where id="+id;

		DbTool.execute(cmd);

	}

	public static void update(User u){

		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");

		String cmd = "update t_user set username='"+

				u.getUsername()+"',password='"+

				u.getPassword()+"',birthday='"+

				sdf.format(u.getBirthday())+"' where id="+

				u.getId();

		DbTool.execute(cmd);

	}

	public static int getUsersCount(){

		int count = 0;

		String cmd = "select count(*) from t_user";

		Object o = DbTool.getOneResult(cmd);

		if(null != o){

			count = ((Long)o).intValue();

		}

		return count;

	}

	public static PageBean getSomeUser(int pageSize,int pageNum){

		PageBean pb = new PageBean();

		int rowCount = getUsersCount();

		int pageCount = rowCount%pageSize ==0 ? rowCount/pageSize: rowCount/pageSize+1;

		if(pageNum<1)pageNum = 1;

		if(pageNum>pageCount)pageNum=pageCount;

		int first = (pageNum-1)*pageSize;

		String cmd = "select * from t_user limit "+first+","+pageSize;

		Connection conn = DbTool.getConnection();

		List<User> users = new ArrayList<User>();

		try{

			Statement st = conn.createStatement();

			ResultSet rs = st.executeQuery(cmd);

			while (rs.next()){

				User u = new User();

				u.setId(rs.getInt(1));

				u.setUsername(rs.getString(2));

				u.setPassword(rs.getString(3));

				u.setBirthday(rs.getDate(4));

				users.add(u);

			}

		}catch(Exception exp){

			exp.printStackTrace();

		}

		DbTool.closeConnection(conn);

		pb.setContents(users);

		pb.setPageCount(pageCount);

		pb.setPageNum(pageNum);

		pb.setPageSize(pageSize);

		pb.setRowCount(rowCount);

		return pb;

	}

}

package servlet;

import java.io.IOException;

import javax.servlet.RequestDispatcher;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import dao.UserDao;

import bean.PageBean;

public class UserList extends HttpServlet {

	@Override

	protected void service(HttpServletRequest request, HttpServletResponse response)

			throws ServletException, IOException {

		String pn = request.getParameter("pageNum");

		int pageNum = 1;

		if(null != pn && pn.length()>0){

			pageNum = Integer.parseInt(pn);

		}

		PageBean pb = UserDao.getSomeUser(5, pageNum);

		request.setAttribute("pageBean", pb);

		RequestDispatcher rd = request.getRequestDispatcher("user_list.jsp");

		rd.forward(request, response);

	}

}

<%@page import="java.util.Date"%>

<%@page import="java.text.SimpleDateFormat"%>

<%@page import="bean.User"%>

<%@page import="java.util.List"%>

<%@page import="bean.PageBean"%>

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

    pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>

</head>

<body>

<table>

	<tr>

		<td>id</td>

		<td>用户名</td>

		<td>密码</td>

		<td>生日</td>

	</tr>

<%

	PageBean pb = (PageBean)request.getAttribute("pageBean");

	List<User> users = (List<User>)pb.getContents();

	int pageNum = pb.getPageNum();

	int pageCount = pb.getPageCount();

	int pageSize = pb.getPageSize();

	int rowCount = pb.getRowCount();

	for(User u : users){

		Date bir = u.getBirthday();

		String birthday = new SimpleDateFormat("yyyy-MM-dd").format(bir);

%>

	<tr>

		<td><%=u.getId() %></td>

		<td><%=u.getUsername() %></td>

		<td><%=u.getPassword()%></td>

		<td><%=birthday %></td>

	</tr>

<%

	}

%>

</table>

共<%=rowCount %>条记录，当前是第<%=pageNum %> / <%=pageCount %>页，每页显示<%=pageSize %>条记录。<br/>

<a href="userList?pageNum=1">第一页</a>

<a href="userList?pageNum=<%=pageNum-1 %>">上一页</a>

<a href="userList?pageNum=<%=pageNum+1 %>">下一页</a>

<a href="userList?pageNum=<%=pageCount %>">最后页</a>

</body>

</html>

三.结束语

虽然技术上不是问题，不过怎么分包却是大问题，目前还没有好办法。。。。。