自定义MVC之通用增删改查

一、搭建自定义MVC框架环境 将我们之前所写的自定义MVC框架导成jar包，再新建一个增删改查项目导入这个jar包，之后再配置xml文件

 特别是截图里的箭头位置需要注意，否则会导致我们的jar包无法正常使用

二、通用增删改查 1.通用类BaseDao 首先我们先定义一个通用的增删改查 因为增删改都是需要提交事务的，而查询不需要，所以我们将增删改写成了一个通用的方法，在子类中调用方法时只需要定义不同的sql语句，和参数就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 {

	public List executeQuery( String sql,PageBean pagebean,CallBack callBack) throws Exception{
		
		
		
		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();
		}
		//查询不同的表必然要处理不同的结果集
		return callBack.foreach(rs);
	}

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

	
	private String getCountsql(String sql) {
		// TODO Auto-generated method stub
		return " select count(1) as n from ("+sql+") t";
	}
	
	
	
	
	public int executeUpdate(String sql,T t,String[] strings) throws Exception {
		Connection con = DBAccess.getConnection();
		PreparedStatement ps = con.prepareStatement(sql);
		//将t的某一个对应值加到ps对象中
		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));//下标从0开始
		}
		
		
		return ps.executeUpdate();
	}
}

2.BookDao  根据方法的不同，sql语句和参数也不同

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{

	
	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();
		if(bid !=0) {
			sql +=" and bid = "+bid;
			
		}
		
		//调用父类的查询方法
		return super.executeQuery(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;
		});
	}
	
	
	
	
	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"});
	}
	 
	
	public int delete(Book book) throws Exception {
		String sql = "delete from t_mvc_book where bid = ?";
		return super.executeUpdate(sql, book, new String[] {"bid"});
	}
	
	 
		
	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、在BookAction中写好对应的方法 遵循先继承后实现的规则，分别调用父类和接口的方法

public class BookAction extends ActionSupport implements ModelDriven{

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

	

	//增加
	public String add(HttpServletRequest req, HttpServletResponse resp) {
		try {
			bd.add(book);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return "toList";
	}
	
	//删除
		public String delete(HttpServletRequest req, HttpServletResponse resp) {
			try {
				bd.delete(book);
			} catch (Exception e) {
				e.printStackTrace();
			}
			return "toList";
		}
		
		//修改
		//增加
		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 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 list=bd.list(book, null);
				req.setAttribute("b", list.get(0));
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		return "toEdit";

}

4、在Junit中测试

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

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

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

	
}

三、前端Jsp界面 1、主界面

   

<%@ 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"%>










	

		
			
			
			
			
		
		查询
		新增
	
 
	
				

		

			

				
书籍ID
				
书籍名
				
价格
				
操作
			
		
		

			

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

     2、BookEdit(增加和修改的界面)

<%@ 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"%>	









	

		书籍ID：

		书籍名称：

		书籍价格：

		
	
 
 

四、总结 1、使用自定义MVC的步骤：
                 1.1、导入自己导出的自定义MVC.jar包
                 1.2、做好框架的相应配置(导入之前MVC.jar包依赖的jar包)
                 1.3 、一切照旧 （jsp界面，bookaction、dao层、entity）
          2、通用增删改查的区别与相同：
                 2.1共同点：增删改查最终都要跳回查询界面
                 2.2不同点：2.2.1:查询：bookList.jsp  返回值：list
                                    2.2.2:增删改确定：book.action？methodName=list  返回值：toList
                                    2.2.3增加修改跳转对应的界面：bookEdit.jsp  返回值是toEdit