JSP中c:foreach遍历和s:iterator遍历异同实例分析

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);
 }
}

<%@ 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="/UploadFiles/2021-04-02/topic.gif">

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="/UploadFiles/2021-04-02/topic.gif">

希望本文所述对大家的JSP程序设计有所帮助。