在上一期讲了EL表达式和JSTL标签，这期来讲讲EL表达式与JSTL标签的用法，在了解EL表达式与JSTL标签后又可以将网页中的Java代码答题一部分,从而达到Java代码与网页代码进一步分离的效果，大大降低耦合性，下面直接开始上代码吧
IGoodsDao.java:
package com.zking.dao;
import java.util.List;
import com.zking.pojo.Goods;
public interface IGoodsDao {
//查询所有
List getAll(int page);
//查询单个
Goods getOne(Integer id);
//查询所有页数
int getRowCount();
}
GoodsDaoImpl.java:
package com.zking.dao.impl;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;
import com.zking.dao.IGoodsDao;
import com.zking.pojo.Goods;
import com.zking.pojo.User;
import com.zking.util.DBHelper;
public class GoodsDaolmpl implements IGoodsDao{
private Connection con;
private PreparedStatement ps;
private ResultSet rs;
@Override
public List getAll(int page) {
int size=5;//页面数据条数
int begin=(page-1)*size+1;
int end=page*size;
List list = new ArrayList();
try {
con=DBHelper.getCon();
String sql="select * from (select a.*,rownum myr from shop_goods a) b where myr between ? and ?";
ps=con.prepareStatement(sql);
ps.setInt(1,begin);
ps.setInt(2,end);
rs=ps.executeQuery();
while(rs.next()) {
Goods goods=new Goods();
goods.setId(rs.getInt(1));
goods.setName(rs.getString(2));
goods.setPrice(rs.getInt(3));
goods.setInfo(rs.getString(4));
list.add(goods);
}
return list;
} catch (Exception e) {
e.printStackTrace();
}finally {
DBHelper.close(con, ps, rs);
}
return list;
}
@Override
public Goods getOne(Integer id) {
try {
con = DBHelper.getCon();
ps = con.prepareStatement("select * from shop_goods where id=?");
ps.setInt(1, id);
rs = ps.executeQuery();
if (rs.next()) {
Goods goods = new Goods();
goods.setId(rs.getInt(1));
goods.setName(rs.getString(2));
goods.setPrice(rs.getInt(3));
goods.setInfo(rs.getString(4));
return goods;
}
} catch (Exception e) {
e.printStackTrace();
} finally {
DBHelper.close(con, ps, rs);
}
return null;
}
@Override
public int getRowCount() {
try {
con = DBHelper.getCon();
ps = con.prepareStatement("select count(1) from shop_goods");
rs = ps.executeQuery();
if(rs.next()) {
return rs.getInt(1);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
DBHelper.close(con, ps, rs);
}
return 0;
}
}
IGoodsBiz.java:
package com.zking.biz;
import java.util.List;
import com.zking.pojo.Goods;
public interface IGoodsBiz {
List getAll(int page);
//查询单个
Goods getOne(Integer id);
//查询所有页数
int getRowCount();
}
GoodsBizImpl.java:
package com.zking.biz.impl;
import java.util.List;
import com.zking.biz.IGoodsBiz;
import com.zking.dao.IGoodsDao;
import com.zking.dao.impl.GoodsDaolmpl;
import com.zking.pojo.Goods;
public class GoodsBizlmpl implements IGoodsBiz{
private IGoodsDao goodsDao=new GoodsDaolmpl();
@Override
public List getAll(int page) {
return goodsDao.getAll(page);
}
@Override
public Goods getOne(Integer id) {
return goodsDao.getOne(id);
}
@Override
public int getRowCount() {
// TODO Auto-generated method stub
return goodsDao.getRowCount();
}
}
index.jsp:
<%@page import="org.apache.jasper.tagplugins.jstl.core.ForEach"%>
<%@page import="com.zking.pojo.Goods"%>
<%@page import="com.zking.biz.impl.GoodsBizlmpl"%>
<%@page import="com.zking.biz.IGoodsBiz"%>
<%@page import="com.zking.pojo.User"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
Document
doIndex.jsp：
<%@page import="com.zking.biz.impl.GoodsBizlmpl"%>
<%@page import="com.zking.biz.IGoodsBiz"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%
String parameter = request.getParameter("ipage");
int ipage=1;//默认第一页
if(parameter!=null){
ipage=Integer.parseInt(parameter);
}
//得到商品的Biz
IGoodsBiz goodsBiz=new GoodsBizlmpl();
//将商品查询出来 并且放到请求域当中
request.setAttribute("goods", goodsBiz.getAll(ipage));
//算出也数，带导index.jsp
int row = goodsBiz.getRowCount();
request.setAttribute("maxPage", (int)Math.ceil(row*1.0/4)) ;
request.setAttribute("ipage", ipage);
//把数据携带导index.jsp
request.getRequestDispatcher("index.jsp").forward(request,response);
%>
https://blog.csdn.net/m0_63772104/article/details/car.jsp:
<%@page import="com.zking.vo.CarItem"%>
<%@page import="java.util.List"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
Document
| 商品序号 | 商品名称 | 商品个数 | 商品总价 | 操作 |
|---|---|---|---|---|
| ${c.goods.id } | ${c.goods.name } | ${c.sum} | 删除 |
当前购物车总价 xx 点我结算
本期分享内容中使用了一部分EL表达式和JSTL标签代替了一部分Java代码
好了今天的内容就分享到这了
