自定义mvc增删改查

矫情吗；* 2021-12-20 05:55 239阅读 0赞

对t\_mvc\_book表的增删改查

导入jar包

![1691548-20190627183401955-1363723087.png][]

BaseDao

package com.hmc.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;
    
    /**
     * T代表你要对哪个实体类对应表进行查询
     * 
     * @author Administrator
     *
     * @param <T>
     */
    public class BaseDao<T> {
     
    	/**
    	 * 
    	 * @param sql 查询不同的实体类，那么对应的sql不同，所以需要传递 
    	 * @param clz  生产出不同的实体类对应的实例，然后装进list容器中返回
    	 * @param pageBean  决定是否分页
    	 * @return
    	 * @throws Exception 
    	 */
    	public List<T> executeQuery(String sql,Class clz,PageBean pageBean) throws Exception{
    		
    		Connection con=DBAccess.getConnection();
    		PreparedStatement ps=null;
    		ResultSet rs=null;
    	   if(pageBean!=null&&pageBean.isPagination()) {
    		   //需要分页(算符合条件的总记录数)
    		   String countSql=getCountSql(sql);
    		   ps=con.prepareStatement(countSql);
    		   rs=ps.executeQuery();
    		   if(rs.next()) {
    			   pageBean.setTotal(rs.getLong(1)+"");
    		   }
    		   //查询出符合条件的结果集
    		   String pageSql=getpageSql(sql,pageBean);
    		   ps=con.prepareStatement(pageSql);
    		   rs=ps.executeQuery();
    		   
    	   }else {
    		   ps=con.prepareStatement(sql);
    		   rs=ps.executeQuery();
    	   }
    		
    		
    		
    		
    		List<T> list=new ArrayList<T>();
    	    T t;
    		while(rs.next()) {
    		/**
    		 * 1.实例化一个book对象（该对象是空的）
    		 * 2.取book的所有的属性，然后给其赋值
    		 *  2.1获取所有属性对象
    		 *  2.2给属性对象赋值
    		 * 3.赋完值的book对象装进list容器中
    		 */
    		t=(T)clz.newInstance();
    			Field[] fields=clz.getDeclaredFields();
    			for (Field field : fields) {
    				field.setAccessible(true);
    				field.set(t, rs.getObject(field.getName()));
    			}
    			list.add(t);
    		}
    		DBAccess.close(con, ps, rs);
    		return list;
    	}
       
    	/**
    	 * 利用原生sql拼接出符合条件的结果集的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();
    	}
    
    	/**
    	 * 获取符合条件的总记录数的sql
    	 * @param sql
    	 * @return
    	 */
    	private String getCountSql(String sql) {
          
    		
    		return "SELECT COUNT(1)FROM ("+sql+")t";
    	}
    	
    	/**
    	 * 
    	 * @param sql 决定增删改的一种
    	 * @param attrs 决定？位置 new String[]{"bid,"bname"}
    	 * @param t 要操作的实体
    	 * @return
    	 * @throws Exception 
    	 * @throws NoSuchFieldException 
    	 */
    	public int executeUpdate (String sql,String[] attrs,T t) throws NoSuchFieldException, Exception {
    		Connection con=DBAccess.getConnection();
    		PreparedStatement ps=con.prepareStatement(sql);
    		for(int i=1;i<=attrs.length;i++) {
    		Field f=t.getClass().getDeclaredField(attrs[i-1]);
    		f.setAccessible(true);
    		ps.setObject(i, f.get(t));
    		}
    		int num=ps.executeUpdate();
    		DBAccess.close(con, ps, null);
    		
    		return num;
    	}
    	 
    	
    }

Book(实体)

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

BookDao

package com.hmc.dao;
    
    import java.util.List;
    
    import com.hmc.entity.Book;
    import com.hmc.util.BaseDao;
    import com.hmc.util.PageBean;
    import com.hmc.util.StringUtils;
    
    public class BookDao extends BaseDao<Book>{
    	/**
    	 * 查询所有
    	 * @param book
    	 * @param pageBean
    	 * @return
    	 * @throws Exception
    	 */
      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); 
    	  
      }
      /**
       * 修改
       * @param book
       * @return
     * @throws Exception 
     * @throws NoSuchFieldException 
       */
      public int upde(Book book) throws NoSuchFieldException, Exception {
    	  String sql="update t_mvc_book set bname=?,price=? where bid=?";
      return super.executeUpdate(sql, new String[] {"bname","price","bid"}, book);
      }
      
      /**
       * 新增
       * @param book
       * @return
     * @throws Exception 
     * @throws NoSuchFieldException 
       */
      public int add(Book book) throws NoSuchFieldException, Exception {
    	  String sql="insert into t_mvc_book values(?,?,?)";
    	  System.out.println(sql);
      return super.executeUpdate(sql, new String[] {"bid","bname","price"}, book);
      }
      
      /**
       * 删除
       * @param book
       * @return
     * @throws Exception 
     * @throws NoSuchFieldException 
       */
      public int del(Book book) throws NoSuchFieldException, Exception {
    	  String sql="delete from t_mvc_book where bid=?";
    	  
      return super.executeUpdate(sql, new String[] {"bid"}, book);
      }
    }

BookAction

package com.hmc.web;
    
    import java.util.List;
    
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    import com.hmc.dao.BookDao;
    import com.hmc.entity.Book;
    import com.hmc.framework.ActionSupport;
    import com.hmc.framework.ModelDrivern;
    import com.hmc.util.PageBean;
    
    public class BookAction extends ActionSupport implements ModelDrivern<Book>{
         private Book book=new Book();
         private BookDao bookdao=new BookDao();
         /**
          * 分页查询
          * @param request
          * @param response
          * @return
          * @throws Exception
          */
        
         public String list(HttpServletRequest request,HttpServletResponse response) throws Exception {
        	 PageBean pageBean=new PageBean();
        	 pageBean.setRequest(request);
        	 List<Book> list = this.bookdao.list(book, pageBean);
        	 request.setAttribute("booklist", list);
    		 request.setAttribute("pagebean", pageBean);
        	 return "list";
         }
         
         /**
          * 
          * 跳转到增加或修改页面
          * @param request
          * @param response
          * @return
          * @throws Exception
          */
         public String preSave(HttpServletRequest request,HttpServletResponse response) {
    		//bid的类型是int类型，而int类型的默认值是0，如果jsp未传递bid的参数值那么bid=0;
        	 if(book.getBid()==0) {
    			System.out.println("增加逻辑");
    			
    		  }
    		else {
    			//修改数据回显
    			Book b;
    			try {
    				b = this.bookdao.list(book, null).get(0);
    				request.setAttribute("book", b);
    			} catch (Exception e) {
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    		    
    		}
        	 return "edit";
          
         
         }
         
         /**
          * 新增
          * @param request
          * @param response
          * @return
          * @throws Exception
          */
         public String add(HttpServletRequest request,HttpServletResponse response) throws Exception {
    		//新增完了之后刷新页面
        	this.bookdao.add(book);
        	 return "tolist";
         
         }
         
          /**
           * 修改
           * @param request
           * @param response
           * @return
           * @throws Exception
           */
         public String upde(HttpServletRequest request,HttpServletResponse response) throws Exception {
     		//修改完了之后刷新页面
         	 this.bookdao.upde(book);
         	 return "tolist";
          
          }
         /**
          * 删除
          * @param request
          * @param response
          * @return
          * @throws Exception
          */
         public String del(HttpServletRequest request,HttpServletResponse response) throws Exception {
      		//删除之后刷新页面
          	this.bookdao.del(book);
          	return "tolist";
           }
         
    	@Override
    	public Book getModel() {
    		// TODO Auto-generated method stub
    		return book;
    	}
         
    }

mvc.xml

<?xml version="1.0" encoding="UTF-8"?>
    
    <config>
    	
    
    	<action path="/Cal" type="com.hmc.web.AddCalAction">
    		<forward name="res" path="/res.jsp" redirect="false" />
    	</action>
    	<action path="/book" type="com.hmc.web.BookAction">
    		<forward name="list" path="/book.jsp" redirect="false" />
    		<forward name="edit" path="/booklist.jsp" redirect="false" />
    		<forward name="tolist" path="/book.action?menthodName=list" />
    	</action>
    </config>

建立web层进行测试（book.jsp）

<%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
        <%@page isELIgnored="false" %>
        <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
        <%@taglib prefix="z"  uri="/MyJSP"%>
    <!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?menthodName=list"
    		method="post">
    		书名：<input type="text" name="bname"> <input type="submit"
    			value="确定">
    			
    	</form>
    	<a href="${pageContext.request.contextPath}/book.action?menthodName=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="${pageContext.request.contextPath}/book.action?menthodName=preSave&&bid=${b.bid}">修改</a>
    				</td>
    				<td><a href="${pageContext.request.contextPath}/book.action?menthodName=del&&bid=${b.bid}">删除</a>
    				</td>
    			</tr>
    		</c:forEach>
    	</table>
    <z:page bean="${pagebean }"></z:page> 
    
    	
    </body>
    </html>

![1691548-20190627183546826-520503771.png][]

模糊查询

![1691548-20190627183710191-822334503.png][]

删除上面编号为23的

![1691548-20190627183800405-1554208397.png][]

新增书籍

![1691548-20190627184028188-1093396861.png][]

![1691548-20190627184052354-472147897.png][]

修改十里桃花为百里桃花

![1691548-20190627184214335-167870953.png][]

转载于:https://www.cnblogs.com/xmf3628/p/11098932.html

[1691548-20190627183401955-1363723087.png]: /images/20211220/49d83a7a06bb44c0811e8848d962f76d.png
[1691548-20190627183546826-520503771.png]: /images/20211220/711769ea44454e778f6a89f6c0c82423.png
[1691548-20190627183710191-822334503.png]: /images/20211220/5bea2209d6dd4c31abb425f1babdce20.png
[1691548-20190627183800405-1554208397.png]: /images/20211220/902f5ade07ad4c9a9d0665a847f85153.png
[1691548-20190627184028188-1093396861.png]: /images/20211220/0930b002e55546e8ade1e2ddde42ee4a.png
[1691548-20190627184052354-472147897.png]: /images/20211220/70d103408d544fecaa11f94bb678dcd2.png
[1691548-20190627184214335-167870953.png]: /images/20211220/358bfd9cf2b34a6b9fb49cb1787cddab.png