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How to write jsp

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(*-*)浩Original
2019-05-18 14:50:505663browse

Try not to write java code in jsp. That was the way JSP was written a long time ago when it first came out. Later it was found to be very difficult to maintain and modify, so the current type of EL expression ${} appeared.

How to write jsp

Writing method in ancient times (java code and html code are directly mixed and written):

<body>
   	<h1>购物车</h1>
   	<table border="1">
   		<tr>
			<th>商品名称</th>
			<th>商品数量</th>
   		</tr>
   		<%
   			Map<String,Integer> cart = (Map<String,Integer>)session.getAttribute("cart");
   			if(cart!=null && cart.size()>0){
   				for(Entry<String,Integer> en : cart.entrySet()){
   				%>
   				<tr>
					<td><%=en.getKey() %></td>
					<td><%=en.getValue() %></td>
		   		</tr>
   				<% }
   			}
   		 %>
   	</table>
  </body>

Modern writing method (JSTL tag )

<table border="1">
    	<tr>
    		<th>用户名</th>
    		<th>当前遍历索引</th>
    		<th>当前遍历计数</th>
    		<th>是否是集合第一个元素</th>
    		<th>是否是集合最后一个元素</th>
    	</tr>
	     <c:forEach items="${list}" var="name" varStatus="st" >
		    <tr class="${st.index%2==0?"one":"two"}" >
	    		<td>${name}</td>
	    		<td>${st.index}</td>
	    		<td>${st.count}</td>
	    		<td>${st.first}</td>
	    		<td>${st.last}</td>
	    	</tr>
	    </c:forEach>
    </table>
<hr> 
	<!--  数数的功能-->
	<c:forEach begin="1" end="10" step="1" var="num" >
		${num}
	</c:forEach>

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