JSP中c:foreach遍历和s:iterator遍历异同实例分析


            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。