自定义MVC（增删改查）

最新推荐文章于 2022-08-19 10:29:46 发布

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#自定义MVC（增删改查）

t_mvc_book 表的增删改查

1、通用分页的jar、自定义mvc框架、自定义标签
导入jar、导入之前写好的pageTag、自定义mvc.xml

在这里插入图片描述

2、dao层通用的增删改方法

BaseDao

package com.util;

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



/**
 * 用来处理所有的表的通用的增删改查的基类
 * 
 * @author 17628
 *
 */
public class BaseDao<T> {
	/**
	 * @param sql
	 *            可能查不同的表，那么意味着sql语句是变化的，那么它是从子类处理好在传递到父类的
	 * @param clz
	 *            需要返回不同的对象集合 Book.class/Order.class
	 * @param pagebean
	 *            可能要分页
	 * @return
	 * @throws SQLException
	 * @throws IllegalAccessException
	 * @throws InstantiationException
	 */
	public List<T> executeQuery(String sql, Class clz, PageBean pagebean) throws Exception {
			List<T> list = new  ArrayList<>();
			Connection con = DBAccess.getConnection();
			PreparedStatement ps = null;
			ResultSet rs = null;
			
			if(pagebean !=null && pagebean.isPagination()) {  
//	                              分页代码	
				/*
				 * 1、分页是与pagebean中total,意味真需要查询数据库得到total赋值给pagebean
				 * 2、查询出符合条件的某一页的数据
				 */
		 		String countSql=getCountSql(sql);
				ps=con.prepareStatement(countSql);
				rs=ps.executeQuery();
				if(rs.next()) {
					pagebean.setTotal(rs.getInt(1));
				}
				
				// 进行拼接
				String pageSql=getPageSql(sql,pagebean);
				ps = con.prepareStatement(pageSql);
				rs =ps.executeQuery();
			}else {
				ps = con.prepareStatement(sql);
				rs =ps.executeQuery();
			}
			
			T t = null;  // 泛型传过来的对象 进行实例化
			while(rs.next()) {
				t=(T) clz.newInstance();
				Field [] fields = clz.getDeclaredFields();
				for (Field f : fields) {
					f.setAccessible(true);
					f.set(t, rs.getObject(f.getName()));
				}
				list.add(t);
			}
			DBAccess.close(con, ps, rs);
		return list;
	}

	private String getPageSql(String sql,PageBean pagebean) {
		return sql + "limit "+pagebean.getStartIndex()+","+pagebean.getRows() ;
	}

	private String getCountSql(String sql) {   // 获得总记录 查询的数据有多少数据
		return "select count(1) from ("+sql+") t";
		
	}
	/**
	 * 
	 * @param sql 增刪改查的sql語句
	 * @param attrs  代表了SQL语句中的问号
	 * @param t   实体类 （里面包含参数值）
	 * @return
	 * @throws SQLException 
	 * @throws IllegalAccessException 
	 * @throws IllegalArgumentException 
	 */
	public int execute(String sql,String[] attrs, T t) throws IllegalArgumentException, IllegalAccessException, SQLException {
		Connection con=DBAccess.getConnection();
		PreparedStatement  ps=con.prepareStatement(sql);
//		ps.setInt(1, book.getBid());
//		ps.setString(2, book.getBname());
//		ps.setFloat(3, book.getPrice());
		
	 Field[] fields=t.getClass().getDeclaredFields();
		for (int i = 0; i < attrs.length; i++) {
			fields[i].setAccessible(true);
			ps.setObject(i+1,fields[i].get(t));
		}
		int num=ps.executeUpdate();
		
		DBAccess.close(con, ps, null);
		return num;
	}
}

BookDao（继承 BaseDao）

package com.dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.List;

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

public class BookDao extends BaseDao<Book>{
public  List<Book> list(Book book,PageBean pageBean) throws Exception{
	String sql="select * from t_mvc_book where true";
	String bname=book.getBname();
	int bid=book.getBid();
	if(StringUtils.isNotBlank(bname)) {
		sql +=" and bname like '%"+bname+"%'";
	}
	if(bid!=0) {
		sql +=" and bid="+bid;
	}
	return super.executeQuery(sql, Book.class, pageBean);
}
public  int add(Book book) throws Exception {
	String sql="insert into t_mvc_book values(?,?,?)";
	
	return super.execute(sql, new String[] {"bid","bname","price"}, book);
}
public  int edit(Book book) throws Exception {
	String sql=" update t_mvc_book set bname=?, price=? where bid=?";

	return super.execute(sql, new String[] {"bname,price,bid"}, book);
}
public  int del(Book book) throws Exception {
	String sql=" delete from t_mvc_book  where bid=?";

	return super.execute(sql, new String[] {"bid"}, book);
}
public static void main(String[] args) {
	BookDao bookDao=new BookDao();
	Book book=new Book(141313, "xxx", 56f);
	
	try {
		//bookDao.add(book);
		bookDao.del(book);
	} catch (Exception e) {
		e.printStackTrace();
	}
	
}
}

3、web层（BookAction）

package com.web;

import java.util.List;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.dao.BookDao;
import com.entity.Book;
import com.framewrok.ActionSuppot;
import com.framewrok.ModelDriver;
import com.util.PageBean;

public class BookAction extends ActionSuppot implements ModelDriver<Book>{
private Book book=new Book();
private BookDao bookDao=new BookDao();
public String list(HttpServletRequest req,HttpServletResponse resp) {
	PageBean pageBean=new PageBean();
	pageBean.setRequest(req);
	try {
		  List<Book> list=this.bookDao.list(book, pageBean);
		  req.setAttribute("bookList", list);
		  req.setAttribute("pageBean", pageBean);
	} catch (Exception e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	}
	return "list";
}
/**
 * 调转新增修改页面(新增修改页面是同一个)
 * @param req
 * @param resp
 * @return
 */
public String preSave(HttpServletRequest req,HttpServletResponse resp) {
	if(book.getBid() !=0) {
		//System.out.println("新增页面不作任何操作");
		try {
		Book b=	this.bookDao.list(book, null).get(0);
		req.setAttribute("book", b);
		} catch (Exception e) {
			e.printStackTrace();
		}
		
	}
	
	return "edit";
	
}

public String add(HttpServletRequest req,HttpServletResponse resp) {
	try {
		this.bookDao.add(book);
	} catch (Exception e) {
		e.printStackTrace();
	}
	return "toList";
	
}
public String edit(HttpServletRequest req,HttpServletResponse resp) {
	try {
		this.bookDao.edit(book);
	} catch (Exception e) {
		e.printStackTrace();
	}
	return "toList";
	
}
public String del(HttpServletRequest req,HttpServletResponse resp) {
	try {
		this.bookDao.del(book);
	} catch (Exception e) {
		e.printStackTrace();
	}
	return "toList";
}

@Override
public Book getModel() {
	return book;
}

}

【注意】

增/删/改用重定向,查询用转发
这样做的目的是阻止多次上传请求带来数据重复的影响

<?xml version="1.0" encoding="UTF-8"?>
<config>
	<action path="/book" type="com.caoguangli.web.BookAction">
		<forward name="list" path="/bookList.jsp" redirect="false" />
		<!-- 转发 -->
		<forward name="edit" path="/bookEdit.jsp" redirect="false" />
		<!-- 重定向 -->
		<forward name="toList" path="/book.action?methodName=list" />
	</action>
</config>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>web_mvc</display-name>
  <filter>
  	<filter-name>encodingFiter</filter-name>
  	<filter-class>com.caoguangli.util.EncodingFiter</filter-class>
  </filter>
  <filter-mapping>
  	<filter-name>encodingFiter</filter-name>
  	<url-pattern>*.action</url-pattern>
  </filter-mapping>
  
  <servlet>
  	<servlet-name>dispatcherServlet</servlet-name>
  	<servlet-class>com.caoguangli.framework.DispatcherServlet</servlet-class>
  	<init-param>
  		<param-name>xmlPath</param-name>
  		<param-value>/mvc.xml</param-value>
  	</init-param>
  </servlet>
  <servlet-mapping>
  	<servlet-name>dispatcherServlet</servlet-name>
  	<url-pattern>*.action</url-pattern>
  </servlet-mapping>
  
</web-app>

4、jsp 页面

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ taglib uri="/cbw"  prefix="b"%>
<!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>
<h2>小说目录</h2>
	<br>
	<form action="${pageContext.request.contextPath}/book.action?methodName=list"
		method="post">
		<!--用户设置查询 一页20条记录  -->
		<!-- <input type="hidden" name="rows" value="20"/> -->
		<!--用户设置不分页  -->
	 	<!-- <input type="hidden" name="pagination" value="false"/> -->
		书名：<input type="text" name="bname"> <input type="submit"
			value="确定">
	</form>
	<a href="${pageContext.request.contextPath}/book.action?methodName=preSave">新增</a>
	<table border="1" width="100%">
		<tr>
			<td>编号</td>
			<td>名称</td>
			<td>价格</td>
			<td>操作</td>
		
		</tr>
		<c:forEach items="${bookList}" var="b">
			<tr>
				<td>${b.bid }</td>
				<td>${b.bname }</td>
				<td>${b.price }</td>
				<td>
			<a href="${pageContext.request.contextPath}/book.action?methodName=preSave&&bid=${b.bid}">修改</a>
			<a href="${pageContext.request.contextPath}/book.action?methodName=del">删除</a>
			</td>
			</tr>
		</c:forEach>
	</table>
</body>
<h:page pageBean="${pagebean}"></h:page>
</html>

bookEdit.jsp

<%@ 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>书籍的编辑页面</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/book.action?methodName=${book.bname == null  ? 'add' : 'edit' }" method="post">
 bid:<input type="text" value="${book.bid}" name="bid"><br>
 bname:<input type="text" value="${book.bname}" name="bname"><br>
 price:<input type="text" value="${book.price}" name="price"><br>
 <input type="submit" value="提交">
</form>
</body>
</html>