EL表达式的使用

//////////////////////////////////////////////
		// 数组
		String[] str = {"aaa","bbb","ccc"};
		getServletContext().setAttribute("str", str);
			<c:forEach items="${str }" var="srtArr">
				${srtArr }
			</c:forEach>
		// 集合
		ArrayList<String> list = new ArrayList<>();
		list.add("zhangsan");
		list.add("lisi");
		list.add("wangwu");
			<c:forEach items="${list }" var="strList">
				${strList }
			</c:forEach>
		// 集合
		ArrayList<Person> PList = new ArrayList<>();
		PList.add(new Person("p1","pzs","11"));
		PList.add(new Person("p2","pls","12"));
		PList.add(new Person("p3","pww","13"));
		request.getSession().setAttribute("PList", PList);
			<c:forEach items="${PList }" var="per">
				${per.getPid() }
				${per.getPname() }
				${per.getPage() }
			</c:forEach>
		// map集合
		HashMap<Integer, String> hm = new HashMap<>();
		hm.put(1, "11111");
		hm.put(2, "22222");
		hm.put(3, "33333");
		request.getSession().setAttribute("hm", hm);
			<c:forEach items="${hm }" var="entry">
				${entry.key }
				${entry.value }
			</c:forEach>
		// map集合值是一个对象
		HashMap<String, Person> map = new HashMap<>();
		map.put("p001", new Person("p001","zs","15"));
		map.put("p002", new Person("p002","ls","23"));
		map.put("p003", new Person("p003","ww","19"));
		request.getSession().setAttribute("map", map);
			<c:forEach items="${map }" var="entry" >
				${entry.key }  这个是键<br/>
				${entry.value.getPid() }<br/>
				${entry.value.getPname() }<br/>
				${entry.value.getPage() }<br/>
			</c:forEach>


////////////////////////////////////////////////////
<c:url>标签
                <c:url>标签
		<c:url value="/login.jsp"/>这个标签这样执行的结果是  项目名/login.jsp
		使用：
		<form action="<c:url value='/product?method=2'/>" method="post">
		<a href="<c:url value="/product?method=5&pid=${pro.pid }"/>">商品详情</a>
/////////////////////////////////////////////////////
<!-- 判断数据库中没有任何商品 -->
	<c:if test="${empty pb.datas }">
		<tr>
		    <th colspan="9" style="color: red; text-align: center;">查无商品</th>
		</tr>
	</c:if>