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JSP c:foreach遍历和s:iterator遍历有什么不同?

2015-09-30 14:19:38 来源:www.45fan.com 【

JSP c:foreach遍历和s:iterator遍历有什么不同?

本文实例分析了JSP中c:foreach遍历和s:iterator遍历的异同。分享给大家供大家参考。具体如下:

①jstl c:foreach

首先我们来看一个普通的servlet:

import com.xy.entity.Board;
import com.xy.entity.Topic;
import com.xy.entity.User;
public class ToMainAction extends HttpServlet
{
 private IBoarderDao boardDao = new BoardDaoImpl();
 private ITopicDao topicDao = new TopicDaoImpl();
 private IUserDao userDao = new UserDaoImpl();
 public void doGet(HttpServletRequest request, HttpServletResponse response)
  throws ServletException,IOException
 {
 // 板块列表
 List<Board> boards = boardDao.getAllBoard();
 List<Integer> count = new ArrayList<Integer>();
 List<User> users = new ArrayList<User>();
 List<Topic> lastTopic = new ArrayList<Topic>();
 if (null != boards)
 {
 for (Board b : boards)
 {
 // 回帖数
 List<Topic> topic = topicDao.getTopicByBoardId(b.getborderId());
 if(null!=topic)
 {
  int num = topic.size();
  count.add(num);
 }
 else
 {
  count.add(0);
 }
 // 最近更新
 Topic t = topicDao.getLastTopic(b.getborderId());
 lastTopic.add(t);
 // 最近更新的作者
 User u = userDao.getUserByuId(t.getUid());
 users.add(u);
 }
 request.setAttribute("boards", boards);
 request.setAttribute("count", count);
 request.setAttribute("users", users);
 request.setAttribute("lastTopic", lastTopic);
 RequestDispatcher dis = request.getRequestDispatcher("main.jsp");
 dis.forward(request, response);
 }
 }
 public void doPost
  (HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
 {
 this.doGet(request, response);
 }
}

main.jsp:

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<c:if test="${requestScope.boards!=null}">
 <c:forEach var="b" items="${requestScope.boards}" varStatus="status">
 <tr>
 <td width="6%" height="68">
 </td>
 <td width="67%">
 <div align="left" class="blueSpan">
 <img src="images/topic.gif" width="18" height="21" />
 <a href="logined/ToListAction?boardId=${b.borderId}">
 ${b.borderName}</a>
 </div>
 </td>
 <td>
 ${requestScope.count[status.index]}
 </td>
 <td>
 <p align="left">
 ${requestScope.lastTopic[status.index].title}
 </p>
 <br />
 <p align="left">
  ${requestScope.users[status.index].userName}
 </p>
 <br />
 <p align="left">
 修改时间:
 <br>
 ${requestScope.lastTopic[status.index].modifyTime}
 </p>
 <br />
 </td>
 </tr>
 </c:forEach>
</c:if>

②s:iterator

package com.xy.action;
action
public class ToMainAction extends ActionSupport implements RequestAware
{
 private IBoarderDao boardDao = new BoardDaoImpl();
 private ITopicDao topicDao = new TopicDaoImpl();
 private IUserDao userDao = new UserDaoImpl();
 private Map<String, Object> request;
 public void setBoardDao(IBoarderDao boardDao)
 {
 this.boardDao = boardDao;
 }
 public void setTopicDao(ITopicDao topicDao)
 {
 this.topicDao = topicDao;
 }
 public void setUserDao(IUserDao userDao)
 {
 this.userDao = userDao;
 }
 public String execute()
 {
 // 板块列表
 List<Board> boards = boardDao.getAllBoard();
 List<Integer> count = new ArrayList<Integer>();
 List<User> users = new ArrayList<User>();
 List<Topic> lastTopic = new ArrayList<Topic>();
 if (null != boards)
 {
 for (Board b : boards)
 {
 // 回帖数
 List<Topic> topic = topicDao.getTopicByBoardId(b.getBorderId());
 if (null != topic)
 {
  int num = topic.size();
  count.add(num);
 } else
 {
  count.add(0);
 }
 // 最近更新
 Topic t = topicDao.getLastTopic(b.getBorderId());
 lastTopic.add(t);
 // 最近更新的作者
 User u = userDao.getUserByuId(t.getUid());
 users.add(u);
 }
 request.put("boards", boards);
 request.put("count", count);
 request.put("users", users);
 request.put("lastTopic", lastTopic);
 }
 return SUCCESS;
 }
 public void setRequest(Map<String, Object> request)
 {
 this.request = request;
 }
}

main.jsp:

<%@ taglib uri="/struts-tags" prefix="s"%>
<s:if test="#request.boards!=null">
 <s:iterator value="#request.boards" id="b" status="st">
 <tr>
 <td width="6%" height="68">
 </td>
 <td width="67%">
  <div align="left" class="blueSpan">
 <img src="images/topic.gif" width="18" height="21" />
 <a href="logined/ToListAction?boardId="+<s:property value="#b.borderId"/>+">
  <s:property value="#b.borderName" />
 </a>
 </div>
 </td>
 <td>
 <s:property value=" #request.count[#st.index]" />
 </td>
 <td>
 <br />
 <p align="left">
 <s:property value="#request.lastTopic[#st.index].title" />
 </p>
 <br />
 <p align="left">
 <s:property value=" #request.lastTopic[#st.index].userName" />
 </p>
 <br />
 <p align="left">
 修改时间:
 <br/>
 <s:property value=" #request.lastTopic[#st.index].modifyTime" />
 </p>
 <br />
 </td>
 </tr>
  </s:iterator>
</s:if>

希望本文所述对大家的JSP程序设计有所帮助。


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Tags: JSP 遍历 foreach
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