General addition, deletion, modification and query of custom MVC

One 、 Build custom MVC Framework environment

Customize what we wrote before MVC Frame guide assembly jar package , Create a new addition, deletion, modification and query item and import this jar package , Then configure xml file

  Especially the arrow position in the screenshot needs attention , Otherwise, it will lead to our jar The package is not working properly

Two 、 General addition, deletion, modification and query

1. generic class BaseDao

First, we define a general addition, deletion, modification and query   Because all additions, deletions, and modifications need to commit transactions , Query does not need , So we rewrite the addition and deletion into a general method , When calling methods in subclasses, you only need to define different sql sentence , And parameters are ok 了

package com.zjy.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;



public class BaseDao<T> {

	public List<T> executeQuery( String sql,PageBean pagebean,CallBack<T> callBack) throws Exception{
		
		/**
		 * 1. Get the database connection 
		 * 2. Get preparstatement
		 * 3. perform sql sentence 
		 */
		
		Connection con = null;
		
		PreparedStatement ps = null;
		ResultSet rs = null;
		
		if(pagebean!=null&&pagebean.isPagination()) {
			String countsql = getCountsql(sql);
			 con = DBAccess.getConnection();
			 ps = con.prepareStatement(countsql);
			 rs = ps.executeQuery();
			 if(rs.next()) {
				 pagebean.setTotal(rs.getString("n"));
	
			 }
			 String pageSql= getpageSql(sql,pagebean);
			 con = DBAccess.getConnection();
			 ps = con.prepareStatement(pageSql);
			 rs = ps.executeQuery();
		}else {
			 con = DBAccess.getConnection();
			 ps = con.prepareStatement(sql);
			 rs = ps.executeQuery();
		}
		// Querying different tables must deal with different result sets 
		return callBack.foreach(rs);
	}

	/**
	 *  Splice section N Of page data sql
	 * @param sql
	 * @param pagebean
	 * @return
	 */
	private String getpageSql(String sql, PageBean pagebean) {
	
		return sql +" limit "+pagebean.getStartIndex()+" , "+pagebean.getRows();
	}

	/**
	 *  The total number of records that meet the conditions is Sql
	 * @param sql
	 * @return
	 */
	private String getCountsql(String sql) {
		// TODO Auto-generated method stub
		return " select count(1) as n from ("+sql+") t";
	}
	
	
	/**
	 *  General addition, deletion and modification 
	 * @param sql sql sentence 
	 * @param t  Generic class 
	 * @param strings  Attribute array 
	 * @return
	 * @throws Exception  Throw exceptions 
	 */
	
	public int executeUpdate(String sql,T t,String[] strings) throws Exception {
		Connection con = DBAccess.getConnection();
		PreparedStatement ps = con.prepareStatement(sql);
		// take t A corresponding value of is added to ps In the object 
		for (int i = 0; i < strings.length; i++) {
			Field f = t.getClass().getDeclaredField(strings[i] );
			f.setAccessible(true);
			f.get(t);
			ps.setObject(i+1, f.get(t));// Subscript from 0 Start 
		}
		
		
		return ps.executeUpdate();
	}
}

2.BookDao 

Depending on the method ,sql Statements and parameters are also different

package com.zjy.dao;

import java.util.ArrayList;
import java.util.List;

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

public class BookDao extends BaseDao<Book>{

	/**
	 *  Inquire about 
	 * @param book  Entity class 
	 * @param pagebean  Pagination 
	 * @return
	 * @throws Exception  Throw exceptions 
	 */
	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;
			
		}
		
		// Call the query method of the parent class 
		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 (Exception e) {
				e.printStackTrace();
			}
			return list;
		});
	}
	
	
	
	/**
	 *  Increase method 
	 * @param book  Physical books 
	 * @return  General addition, deletion and modification methods in the parent class 
	 * @throws Exception
	 */
	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"});
	}
	 
	/**
	 *  Delete method 
	 * @param book  Physical books 
	 * @return  General addition, deletion and modification methods in the parent class 
	 * @throws Exception
	 */
	public int delete(Book book) throws Exception {
		String sql = "delete from t_mvc_book where bid = ?";
		return super.executeUpdate(sql, book, new String[] {"bid"});
	}
	
	 
		/**
		 *  Modification method 
		 * @param book  Physical books 
		 * @return  General addition, deletion and modification methods in the parent class 
		 * @throws Exception
		 */
	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、 stay BookAction Write the corresponding method in

Follow the rule of inheritance before implementation , Call the methods of the parent class and interface respectively

public class BookAction extends ActionSupport implements ModelDriven<Book>{

	private Book book = new Book();
	private BookDao bd = new BookDao();
	@Override
	public Book getModel() {
		// TODO Auto-generated method stub
		return null;
	}

	

	// increase 
	public String add(HttpServletRequest req, HttpServletResponse resp) {
		try {
			bd.add(book);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return "toList";
	}
	
	// Delete 
		public String delete(HttpServletRequest req, HttpServletResponse resp) {
			try {
				bd.delete(book);
			} catch (Exception e) {
				e.printStackTrace();
			}
			return "toList";
		}
		
		// modify 
		// increase 
		public String edit(HttpServletRequest req, HttpServletResponse resp) {
			try {
				bd.edit(book);
			} catch (Exception e) {
				e.printStackTrace();
			}
			return "toList";
		}


        public String list(HttpServletRequest req,HttpServletResponse resp)  {
		try {
			PageBean pageBean=new PageBean();
			pageBean.setRequest(req);
			List<Book> list=bd.list(book, pageBean);
			req.setAttribute("books", list);
			req.setAttribute("pageBean", pageBean);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return "list";
	}
	
	public String toEdit(HttpServletRequest req,HttpServletResponse resp)  {
		try {
			if(book.getBid()!=0) {
				List<Book> list=bd.list(book, null);
				req.setAttribute("b", list.get(0));
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		return "toEdit";

}

4、 stay Junit Medium test

package com.zjy.dao;

import static org.junit.jupiter.api.Assertions.*;

import java.util.List;

import org.junit.jupiter.api.Test;

import com.zjy.entity.Book;

class BookDaoTest {

	private BookDao bookDao=new BookDao();

	

	@Test
	public void testList() {
		try {
			List<Book> list = bookDao.list(new Book(), null);
			for (Book book : list) {
				System.out.println(book);
			}
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
 
	// increase 
	@Test
	public void testAdd() {
		Book book = new Book(123, " Xiao Zhu ", 9999);
		try {
			bookDao.add(book);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	
 
	// modify 
	@Test
	public void testEdit() {
		
			Book book = new Book(123, " Father Zhu ", 9999);
			try {
				bookDao.edit(book);
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}

	}
	
	// Delete 
 
	@Test
	public void testDelete() {
	
		Book book = new Book(123, " Father Zhu ", 9999);
		try {
			bookDao.delete(book);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	
}

3、 ... and 、 front end Jsp Interface

1、 main interface

   

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<%@ taglib uri="http://jsp.zhujiayin.zjy" prefix="z"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!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> List of books </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="${pageContext.request.contextPath }/book.action?methodName=list"
		method="post">
		<div class="form-group mb-2">
			<input type="text" class="form-control-plaintext" name="bname"
				placeholder=" Please enter the name of the book ">
			<!-- 			<input name="rows" value="20" type="hidden"> -->
			<!--  I don't want to  -->
			<input name="pagination" value="false" type="hidden">
		</div>
		<button type="submit" class="btn btn-primary mb-2"> Inquire about </button>
		<a class="btn btn-primary mb-2"
			href="${pageContext.request.contextPath }/book.action?methodName=toEdit"> newly added </a>
	</form>
 
	<table class="table table-striped bg-success">
		<thead>
			<tr>
				<th scope="col"> Books ID</th>
				<th scope="col"> Book title </th>
				<th scope="col"> Price </th>
				<th scope="col"> operation </th>
			</tr>
		</thead>
		<tbody>
			<c:forEach var="b" items="${books }">
				<tr>
					<td>${b.bid }</td>
					<td>${b.bname }</td>
					<td>${b.price }</td>
					<td><a
						href="${pageContext.request.contextPath }/book.action?methodName=toEdit&bid=${b.bid}"> modify </a>
						<a
						href="${pageContext.request.contextPath }/book.action?methodName=delete&bid=${b.bid}"> Delete </a>
					</td>
				</tr>
			</c:forEach>
		</tbody>
	</table>
	<!--  This line of code is equivalent to dozens of lines in front of the paging requirements  -->
	<z:page pageBean="${ pageBean}"></z:page>
 
</body>
</html>

     2、BookEdit( Add and modify interface )

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<%@ taglib uri="http://jsp.zhujiayin.zjy" prefix="z"%>	
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>	
<!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> New books / modify </title>
</head>
<body>
	<form class="form-inline"
		action="${pageContext.request.contextPath }/book.action?methodName=${empty b ? 'add' : 'edit'}" method="post">
		 Books ID：<input type="text" name="bid" value="${b.bid }"><br>
		 Book name ：<input type="text" name="bname" value="${b.bname }"><br>
		 Book price ：<input type="text" name="price" value="${b.price }"><br>
		<input type="submit">
	</form>
 
 
</body>
</html>

Four 、 summary

1、 Use customization MVC Steps for ：
                 1.1、 Import self exported customization MVC.jar package
                 1.2、 Make the corresponding configuration of the framework ( Before the import MVC.jar Packet dependent jar package )
                 1.3 、 Everything remains the same. （jsp Interface ,bookaction、dao layer 、entity）
          2、 The difference between general addition, deletion, modification and query is the same ：
                 2.1 Common ground ： Add, delete, change and query, and finally jump back to the query interface
                 2.2 Difference ：2.2.1: Inquire about ：bookList.jsp   Return value ：list
                                    2.2.2: Add, delete and modify to confirm ：book.action？methodName=list   Return value ：toList
                                    2.2.3 Add the interface corresponding to the modification jump ：bookEdit.jsp   The return value is toEdit