Spring MVC使用jstl 标签c:forEach 遍历输出双层嵌套List的数据_jstl的foreach可以遍历两个数组吗

作者：Monodyee | 2024-03-06 22:21:23

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jstl的foreach可以遍历两个数组吗

具体操作步骤如下：

1、创建Controller。


import java.util.ArrayList;
import java.util.List;
 
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
 
import com.mahaochen.springmvc.domain.Goods;
import com.mahaochen.springmvc.domain.Inventory;
 
@Controller
@RequestMapping("/shop")
public class ShoppingController {
 
	
	@RequestMapping("/shoppingCart")
	public String getShoppingCart(HttpServletRequest request,  HttpServletResponse response,Model model){
		
		model.addAttribute("list", generateData());
		
		return "shoppingCart";
	}
	private List<Inventory> generateData(){
		 List<Inventory> inventories = new ArrayList<Inventory>();
		for(int i=0 ; i<2 ; i++){
			switch (i) {
			case 0:
				Inventory inventory1 = new Inventory();
				inventory1.setInventoryType("水果");
				List<Goods> goodsList1 = new ArrayList<Goods>(); 
				for(int j=0;j<5;j++){
					Goods goods = new Goods();
					goods.setGoodsName("苹果"+j);
					goodsList1.add(goods);
				}
				inventory1.setGoodList(goodsList1);
				inventories.add(inventory1);
				break;
			default:
				Inventory inventory2 = new Inventory();
				inventory2.setInventoryType("蔬菜");
				List<Goods> goodsList2 = new ArrayList<Goods>(); 
				for(int j=0;j<5;j++){
					Goods goods = new Goods();
					goods.setGoodsName("茄子"+j);
					goodsList2.add(goods);
				}
				inventory2.setGoodList(goodsList2);
				inventories.add(inventory2);
				break;
			}
		}
		return inventories;
	}
}

2、创建对应的jsp页面。

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>  
<!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>购物车</title>
</head>
<body>
	<c:forEach items="${list }" var="item">
		${item.inventoryType}<br />
		  <c:set value="${item.goodList }" var="subItem"/>
		    <c:forEach items="${subItem }" var="var">
		    --${var.goodsName }<br />
		    </c:forEach>
	</c:forEach>
</body>
</html>

注意事项：

JSTL1.1的库　在JSP2.0(Servlet 2.4)及以后(推荐用JSTL1.1及以上)用：

<%@taglibprefix="c" uri="http://java.sun.com/jsp/jstl/core"%>

web.xml


<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4"
         xmlns="http://java.sun.com/xml/ns/j2ee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" >
</web-app>

在 Servlet2.3及以前，

<%@taglibprefix="c" uri="http://java.sun.com/jstl/core"%>

与2.4比较，以后版本路径少了jsp。

web.xml


<?xml version="1.0" encoding="UTF-8"?>  
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd">  
<web-app>        
</web-app>

不然会出现以下错误：

org.apache.jasper.JasperException:/WEB-INF/jsp/shoppingCart.jsp(line: 10, column: 1) According to TLD or attribute directive in tag file,attribute items does not accept any expressions

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