目录

前言

一、配置自定义mvc框架环境

二、实体类、以及dao方法的编写和优化

三、前台的搭建

四、BookAction的完成、完成mvc.xml的配置和重复提交表单问题

五、效果

今日分享的是自定义mvc的增删改，并将其优化成通用的

提示：以下是本篇文章正文内容，下面案例可供参考

一、配置自定义mvc框架环境

1.将我们上次写的框架打成jar包，然后导入新工程，并且把框架的依赖jar包导入进去

①选中我们之前写的framework，右键选中Export...

②输入框中输入java，然后选中 JAR file，点击next

③选择保存地址，然后Finsih即可

④将之前写的分页标签相关文件、及相关助手类导入

 ⑤将框架的配置文件添加、以及web.xml的配置

 注意：要将我们打出来的jar包所需要的包也导入项目中

 web.xml配置：

  J2EE_crud
  
	mvc  
  	com.mgy.framework.DispatcherServlet
  	
  		configLocation
  		/asd.xml
  	
  
  
  	mvc
	*.action
  

二、实体类、以及dao方法的编写和优化

实体类（书籍类）:

package com.mgy.entity;

public class Book {
	private int bid;
	private String bname;
	private float price;

	@Override
	public String toString() {
		return "Book [bid=" + bid + ", bname=" + bname + ", price=" + price + "]";
	}

	public int getBid() {
		return bid;
	}

	public void setBid(int bid) {
		this.bid = bid;
	}

	public String getBname() {
		return bname;
	}

	public void setBname(String bname) {
		this.bname = bname;
	}

	public float getPrice() {
		return price;
	}

	public void setPrice(float price) {
		this.price = price;
	}
	
	public Book() {
		super();
	}

	public Book(int bid, String bname, float price) {
		super();
		this.bid = bid;
		this.bname = bname;
		this.price = price;
	}
	
	
}

基础的dao方法：

package com.mgy.dao;

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

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

public class BookDao extends BaseDao{
	//查询
	public List 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();
		//前台jsp传递到后台，只要传了就有值
		if(bid!=0) {
			sql+=" and bid="+bid;
		}
		return super.list(sql, pageBean, rs ->{
			List 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;
		});
	}
	
	//增加
	public int add(Book book) throws Exception {
		Connection con = DBAccess.getConnection();
		String sql="insert into t_mvc_book values(?,?,?)";
		PreparedStatement ps = con.prepareStatement(sql);
		ps.setObject(1, book.getBid());
		ps.setObject(2, book.getBname());
		ps.setObject(3, book.getPrice());
		return ps.executeUpdate();
	}
	
	//删
	public int del(Book book)throws Exception {
		Connection con = DBAccess.getConnection();
		String sql = "delete from t_mvc_book where bid=?";
		PreparedStatement pst = con.prepareStatement(sql);
		pst.setObject(1, book.getBid());
		return pst.executeUpdate();
	}
	
	
	//改
	public int edit(Book book)throws Exception{
		Connection con = DBAccess.getConnection();
		String sql = "update  t_mvc_book set bname=?,price=? where bid=?";
		PreparedStatement pst = con.prepareStatement(sql);
		pst.setObject(1, book.getBname());
		pst.setObject(2, book.getPrice());
		pst.setObject(3, book.getBid());
		return pst.executeUpdate();
	}
	
}

我们可以发现增删改中都有重复的代码块，所以我们在BaseDao中添加以下方法

	public int executeUpdate(String sql,T t,String[] attrs ) throws Exception{
		Connection con = DBAccess.getConnection();
		PreparedStatement pst = con.prepareStatement(sql);
		//将t的某一个属性对应的值加到pst对象中
		for (int i = 0; i < attrs.length; i++) {
			Field f = t.getClass().getDeclaredField(attrs[i]);
			f.setAccessible(true);
			pst.setObject(i+1, f.get(t));
		}
//		pst.setObject(1, book.getBid());
//		pst.setObject(2, book.getBname());
//		pst.setObject(3, book.getPrice());
		return pst.executeUpdate();
	
	}

通用增删改查：

package com.mgy.dao;

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

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

public class BookDao extends BaseDao{
	//查询
	public List 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();
		//前台jsp传递到后台，只要传了就有值
		if(bid!=0) {
			sql+=" and bid="+bid;
		}
		return super.list(sql, pageBean, rs ->{
			List 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;
		});
	}
	
	//增
	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
	public int del(Book book)throws Exception{
		String sql="delete from t_mvc_book where bid=?";
		return super.executeUpdate(sql, book, new String[] {"bid"});
	}
	
	//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"});
	}
}

三、前台的搭建

主界面：

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<%@ taglib uri="http://jsp.veryedu.cn"  prefix="z"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core"  prefix="c"%>




  
 



 




<%-- 
	
 --%>
	

		
			
		
		查询
		增加
		
	

	
			

		

			

				
书籍ID
				
书籍名
				
价格
				
操作
			
		
		

		

				
${b.bid }
				
${b.bname }
				
${b.price }
				

					修改
					删除
				
				
			
		
		

		
	
	
	

 增加界面&修改界面：

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








	

		bid:

		bname:

		price:

		
	
	

四、BookAction的完成、完成mvc.xml的配置和重复提交表单问题

mvc.xml：

BookAction：

package com.mgy.web;

import java.util.List;

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

import com.mgy.dao.BookDao;
import com.mgy.entity.Book;
import com.mgy.framework.ActionSupport;
import com.mgy.framework.ModelDriven;
import com.mgy.util.PageBean;

public class BookAction extends ActionSupport implements ModelDriven{
	private Book book = new Book();
	private BookDao bookDao = new BookDao();
	
	
	@Override
	public Book getModel() {
		return book;
	}

	//增
	public String add(HttpServletRequest request, HttpServletResponse response) {
		
		try {
			bookDao.add(book);
		} catch (Exception e) {
			e.printStackTrace();
		}
		//toList代表跳到查询页面
		return "toList";
	}
	
	
	//删
	public String del(HttpServletRequest request, HttpServletResponse response) {
		
		try {
			bookDao.del(book);
		} catch (Exception e) {
			e.printStackTrace();
		}
		//toList代表跳到查询页面
		return "toList";
	}
	
	
	//改
	public String edit(HttpServletRequest request, HttpServletResponse response) {
		
		try {
			bookDao.edit(book);
		} catch (Exception e) {
			e.printStackTrace();
		}
		//toList代表跳到查询页面
		return "toList";
	}
	
	
	//查
	public String list(HttpServletRequest request, HttpServletResponse response) {
		
		try {
			PageBean pageBean = new PageBean();
			pageBean.setRequest(request);
			List list = bookDao.list(book,pageBean);
			request.setAttribute("list", list);
			request.setAttribute("pageBean", pageBean);
		} catch (Exception e) {
			e.printStackTrace();
		}
		//执行查询展示
		return "list";
	}
	
	//跳转到新增/修改界面
	public String preEdit(HttpServletRequest request, HttpServletResponse response) {
		
		try {
			int bid = book.getBid();
			if(bid!=0) {
				//传递bid到后台，有且只能查出一条数据，那也就意味着list集合中只要一条
				List list = bookDao.list(book, null);
				request.setAttribute("b", list.get(0));
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		//toList代表跳到查询页面
		return "toEdit";
	}
}

五、效果