自定义mvc框架03

最新推荐文章于 2025-12-21 15:46:00 发布

原创最新推荐文章于 2025-12-21 15:46:00 发布 · 84 阅读

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#前端 #大数据

1.搭建自定义mvc框架环境

2.基础的增删改

package com.hz.dao;

import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import com.hz.entity.Book;
import com.hz.util.BaseDao;
import com.hz.util.PageBean;
import com.hz.util.StringUtils;

public class BookDao extends BaseDao<Book>{
//	查看
	public List<Book> list(Book book,PageBean pageBean) throws Exception{
		String sql= "select*from t_mvc_book where 1=1";
		String bname = book.getBname();
		if(StringUtils.isNotBlank(bname)) {
			sql +=" and bname like '%"+bname+"%'";
		}
		int bid = book.getBid();
		if(bid!=0) {
			sql+=" and bid = "+bid;
		}
		return super.executeQuery(sql, pageBean, rs ->{
		List<Book>	list =new ArrayList<>();
		try {
			while(rs.next()) {
				list.add(new Book(rs.getInt("bid"),rs.getString("bname"),rs.getFloat("price")));
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		return list;
		});
	}
	
//	增加
	public int add(Book book) throws Exception {
		String sql="insert into t_mvc_book values(?,?,?)";
		return super.executeUpdate(sql, book, new String[] {"bid","bname","price"});
	}
	
//	删除
	public int del (Book book) throws Exception {
		String sql="delete from t_mvc_book where bid=?";
		return super.executeUpdate(sql, book, new String[] {"bid"});
	}
	
//	修改
	public int edit (Book book) throws Exception {
		String sql="update t_mvc_book set bname=?,price=? where bid=?";
		return super.executeUpdate(sql, book, new String[] {"bname","price","bid"});
	}
}

3.通用的增删改

package com.hz.util;

import java.lang.reflect.Field;
import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import com.hz.entity.Book;

/**
 * T代表的是实体类 可以是Book/User/Goods。。
 * @author Administrator
 *
 * @param <T>
 */
public class BaseDao<T> {
//	public List<T> executeQuery(String sql,PageBean pageBean,CallBack<T> callBack) throws Exception{
////		sql="SELECT * FROM `t_mvc_book` where bname like  '%圣墟%'\r\n" + 
////				"";
////		从上面得到SELECT * FROM `t_mvc_book` where bname like  '%圣墟%'
////		目的是为了得到总记录数-》得到总页数
////		 SELECT * FROM `t_mvc_book` where bname like  '%圣墟%' limit 10,10
//
//		/**
//		 *1.拿到数据库连接
//		 *2.拿到preparestatement
//		 *3.执行sql语句
//		 */
//		Connection con=DBAccess.getConnection();//重复代码1
//		
//		PreparedStatement ps=con.prepareStatement(sql);//重复代码2
//		ResultSet rs=ps.executeQuery();//重复代码3
//		/*while(rs.next()) {
//			list.add(new Book(rs.getInt("bid"),rs.getString("bname"), rs.getFloat("price")));
//		}*/
////		查询不同的表，必然要处理不同的结果集
////		接口是调用方来实现
//		return callBack.foreach(rs);
//		
//	}
	
	
	public List<T> executeQuery(String sql,PageBean pageBean,CallBack<T> callBack) throws Exception{
//		sql="SELECT * FROM `t_mvc_book` where bname like  '%圣墟%'\r\n" + 
//				"";
//		从上面得到SELECT * FROM `t_mvc_book` where bname like  '%圣墟%'
//		目的是为了得到总记录数-》得到总页数
//		 SELECT * FROM `t_mvc_book` where bname like  '%圣墟%' limit 10,10

		/**
		 *1.拿到数据库连接 
		 *2.拿到preparestatement
		 *3.执行sql语句
		 */
		Connection con=null;//重复代码1
		PreparedStatement ps=null;//重复代码2
		ResultSet rs=null;//重复代码3
		if(pageBean!=null&&pageBean.isPagination()) {
			String countSQL=getcOuntSQL(sql);
			con=DBAccess.getConnection();//重复代码1
			ps=con.prepareStatement(countSQL);//重复代码2
			rs=ps.executeQuery();//重复代码3
			if(rs.next()) {
//				当前实体类就包含了总纪录数
				pageBean.setTotal(rs.getString("n"));
			}
			String pageSQL=getPageSQL(sql,pageBean);
			con=DBAccess.getConnection();//重复代码1
			ps=con.prepareStatement(pageSQL);//重复代码2
			rs=ps.executeQuery();//重复代码3
		}
		else {
			con=DBAccess.getConnection();//重复代码1
			ps=con.prepareStatement(sql);//重复代码2
			rs=ps.executeQuery();//重复代码3
		}
		return callBack.foreach(rs);
		
	}

	/**
	 * 拼装第N页的数据SQL
	 * @param sql
	 * @param pageBean
	 * @return
	 */
private String getPageSQL(String sql, PageBean pageBean) {
	// TODO Auto-generated method stub
	return sql+" limit " + pageBean.getStartIndex() +"," + pageBean.getRows();
}

/**
 * 拼装符合条件总记录数的SQL
 * @param sql
 * @return
 */

private String getcOuntSQL(String sql) {
//	sql="SELECT * FROM `t_mvc_book` where bname like  '%圣墟%'\r\n" + 
//	"";
//	select count(1) as n from (SELECT * from 't_mvc_book' where bname like '%圣墟%') t;
	return "select count(1) as n from ("+sql+") t";
}

public int executeUpdate(String sql,T t,String[] sttrs ) throws Exception {
	Connection con=DBAccess.getConnection();
	PreparedStatement ps = con.prepareStatement(sql);
//	将t的摸一个属性对应的值加到pst对象中
	for (int i = 0; i < sttrs.length; i++) {
		Field f = t.getClass().getDeclaredField(sttrs[i]);
		f.setAccessible(true);
		ps.setObject(i+1, f.get(t));
	}
//	ps.setObject(1, book.getBid());
//	ps.setObject(2, book.getBname());
//	ps.setObj ect(3, book.getPrice());
	return ps.executeUpdate();	
}

}

4.查询删除及重复表单提交问题

<?xml version="1.0" encoding="UTF-8"?>
	<!--
		config标签:可以包含0~N个action标签
	-->
<config>
	
	<action path ="/book" type="com.hz.web.BookAction">
		<forward name="list" path="/bookList.jsp" redirect="false" />
		<forward name="toEdit" path="/bookEdit.jsp" redirect="false" />
		<forward name="tolist" path="/book.action?methodName=list" redirect="true" />
		
	</action>
	
	
</config>

5.新增修改的前端实现

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<%@taglib prefix="h" uri="http://jsp.veryedu.cn" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!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">
<link
	href="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/4.5.0/css/bootstrap.css"
	rel="stylesheet">
<script
	src="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/4.5.0/js/bootstrap.js"></script>
<title>书籍列表</title>
<style type="text/css">
.page-item input {
	padding: 0;
	width: 40px;
	height: 100%;
	text-align: center;
	margin: 0 6px;
}

.page-item input, .page-item b {
	line-height: 38px;
	float: left;
	font-weight: 400;
}

.page-item.go-input {
	margin: 0 10px;
}
</style>
</head>
<body>
	<form class="form-inline"
		action="${pageContext.request.contextPath }/book.action?methodName=list" method="post">
		<div class="form-group mb-2">
			<input type="text" class="form-control-plaintext" name="bname"
				placeholder="请输入书籍名称">
		</div>
		<button type="submit" class="btn btn-primary mb-2">查询</button>
		<a class="btn btn-primary mb-2" href="${pageContext.request.contextPath }/book.action?methodName=preEdit" >增加</a>
		
	</form>

	<table class="table table-striped">
		<thead>
			<tr>
				<th scope="col">书籍ID</th>
				<th scope="col">书籍名</th>
				<th scope="col">价格</th>
				<th scope="col">操作</th> 
			
			</tr>
		</thead>
		<tbody>
			<c:forEach items="${list}" var="b">
				<tr>
					<td>${b.bid}</td>
					<td>${b.bname}</td>
					<td>${b.price}</td>
					<td>
						<a href="${pageContext.request.contextPath }/book.action?methodName=preEdit&bid=${b.bid}" >修改</a>
						<a href="${pageContext.request.contextPath }/book.action?methodName=del&bid=${b.bid}" >删除</a>
					
					</td>
				</tr>
			</c:forEach>
		</tbody>
	</table>
	
<!-- 	http://localhost:8080/Y1_mvc_cru/book.action?methodName=list
 -->	
 	<h:page pageBean="${pageBean }"></h:page>
 </body>
</html>

界面展示