1 介绍
由于在项目里采用的是分层的设计，所以这里包括dao，业务组件，servlet等。这里使用mysql，每种dbms的分页查询可能不一样。
2 dao
@Override
public List<T> readByLimit(int pageNo, int countPerPage,String sortColumn,int sortType)
throws DaoException {
if(pageNo != 0 && countPerPage != 0)
{
Connection connection = null;
PreparedStatement pstm = null;
ResultSet set = null;
try {
connection = C3P0Util.getConnection();
String sql = "select * from "+table_name;
if(sortType == IGenericDao.ASC)//判断升序还是降序
{
sql = sql+" order by "+sortColumn+" asc limit ?,?;";
}
else {
sql = sql+" order by "+sortColumn+" desc limit ?,?;";
}
pstm = connection.prepareStatement(sql);
int start = (pageNo - 1) * countPerPage;//起始条数
pstm.setInt(1,start);
pstm.setInt(2, countPerPage);
set = pstm.executeQuery();
/**
* 创建对象列表
*/
if(set != null)
{
List<T> list = new ArrayList<>();
Class tempType = type;
while(set.next())
{
Object temp = tempType.newInstance();//实例化一个类用于获取field的值
Field[] fields = tempType.getDeclaredFields();
for(int i=0;i<fields.length;i++)
{
fields[i].setAccessible(true);//设置field可访问
fields[i].set(temp, set.getObject(fields[i].getName()));//设置field的值
}
list.add((T)temp);
}
return list;
}
throw new DaoException("Empty result");
} catch (Exception e) {
e.printStackTrace();
throw new DaoException("Query Error");
}
finally{
C3P0Util.close(connection, pstm, set);
}
}
else {
throw new DaoException("Arguments Error");
}
}3 业务方法
@Override
public List<News> getNewsByPage(int pageNo, int countPerPage)
throws ServiceException {
try {
List<News> newsList = newsDao.readByLimit(pageNo, countPerPage, "publishTime", IGenericDao.DESC);
return newsList;
} catch (DaoException e) {
e.printStackTrace();
throw new ServiceException(e.getMessage());
}
}4 servlet
package com.lin.news.controller;
import java.io.IOException;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.lin.news.domain.News;
import com.lin.news.exception.ServiceException;
import com.lin.news.service.impl.NewsServiceImpl;
import com.lin.news.service.intf.INewsService;
public class LoadAllNewsController extends HttpServlet {
private static final long serialVersionUID = 1L;
private INewsService newsService = new NewsServiceImpl();
public static final int COUNT_PER_PAGE = 10;//每页显示的条数
//@SuppressWarnings("null")
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
Integer pageNo = Integer.parseInt(request.getParameter("pageNo"));//获得当前页数
request.setAttribute("pageNo", pageNo);
try {
//List<News> newsList = newsService.getAllNews();
List<News> newsList = newsService.getNewsByPage(pageNo, COUNT_PER_PAGE);
request.setAttribute("newsList", newsList);
/**
* 得到最后一页的页数
*/
Integer endPage = newsService.count();
if(endPage % COUNT_PER_PAGE == 0)
{
endPage = endPage / COUNT_PER_PAGE;
}
else {
endPage = endPage / COUNT_PER_PAGE + 1;
}
request.setAttribute("endPage", endPage);
} catch (ServiceException e) {
e.printStackTrace();
}
finally{
request.getRequestDispatcher("/WEB-INF/admin/rootIndex.jsp").include(request, response);
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}4 JSP
在翻页的超链接里面把当前页数作为参数传递给servlet即可。
<div class="col-md-12 column">
<!-- 新闻列表 -->
<c:choose>
<c:when test="${newsList != null && newsList.size() != 0 }">
<table class="table">
<thead>
<tr>
<th>新闻标题</th>
<th>发布时间</th>
<th>城市</th>
<th>分类</th>
<th>编辑</th>
<th>是否审核</th>
</tr>
</thead>
<tbody>
<c:forEach items="${newsList }" var="news">
<c:choose>
<c:when test="${news.examined == 0 }">
<tr class="error">
</c:when>
<c:when test="${news.examined == 1 }">
<tr class="success">
</c:when>
</c:choose>
<td><a
href="root/newsDescription?id=<c:out value="${news.id}"/>"><c:out
value="${news.title }"></c:out></a></td>
<td><fmt:formatDate value="${news.publishTime }"
pattern="yyyy年MM月dd日 HH:mm:SS" /></td>
<td><c:out value="${news.city }"></c:out></td>
<td><c:choose>
<c:when test="${news.category == 1 }">社会</c:when>
<c:when test="${news.category == 2 }">国际</c:when>
<c:when test="${news.category == 3 }">军事</c:when>
<c:when test="${news.category == 4 }">娱乐</c:when>
<c:when test="${news.category == 5 }">时尚</c:when>
<c:when test="${news.category == 6 }">科技</c:when>
<c:when test="${news.category == 7 }">财经</c:when>
<c:when test="${news.category == 8 }">体育</c:when>
<c:when test="${news.category == 9 }">旅游</c:when>
<c:when test="${news.category == 10 }">美食</c:when>
<c:when test="${news.category == 11 }">汽车</c:when>
<c:when test="${news.category == 12 }">教育</c:when>
<c:when test="${news.category == 13 }">其他</c:when>
</c:choose></td>
<td><a
href="root/listNewsByEditorId?id=<c:out value="${news.editorId }"/>"><c:out
value="${news.editor }"></c:out></a></td>
<td><c:choose>
<c:when test="${news.examined == 0 }">未审核</c:when>
<c:otherwise>已审核</c:otherwise>
</c:choose></td>
</tr>
</c:forEach>
</tbody>
</table>
<hr>
<p align="center">
<a href="root/loadAllNews?pageNo=1" class="btn btn-default">第一页</a> <a
<c:if test="${pageNo == 1 }">onclick="return disabled()"</c:if>
href="root/loadAllNews?pageNo=<c:out value="${pageNo - 1}"/>"
class="btn btn-default">上一页</a> <a
<c:if test="${pageNo == endPage }">onclick="return disabled()"</c:if>
href="root/loadAllNews?pageNo=<c:out value="${pageNo +1}"/>"
class="btn btn-default">下一页</a> <a
href="root/loadAllNews?pageNo=<c:out value="${endPage }"/>"
class="btn btn-default">最后一页</a>
<script type="text/javascript">
function disabled() {
return false
}
</script>
</p>
</c:when>
<c:otherwise>
<h3>没有新闻</h3>
</c:otherwise>
</c:choose>
</div>5 界面
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