javaweb09（快速入门之分页）

最新推荐文章于 2025-03-11 11:28:52 发布

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最新推荐文章于 2025-03-11 11:28:52 发布

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分类专栏： javaweb 文章标签： java web

本文链接：https://blog.youkuaiyun.com/qq_67785529/article/details/124262198

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这篇博客主要介绍了JavaWeb开发中的分页查询，包括主页的基本分页实现和带有模糊查询的分页功能，同时也涵盖了项目的导入步骤。

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一.主页分页

二.携带模糊查询的分页

三.导入项目

一.主页分页

	public List<News> queryNewsAll3(int pageIndex,int pageSize) {
		//根据参数pageIndex和pageSize来计算区间查询的规律
		int start = (pageIndex-1)*pageSize +1;
		int end = pageIndex * pageSize;
		
		Connection conn = null;
		PreparedStatement ps = null;
		ResultSet rs = null;
		List<News> list = new ArrayList<News>();
		try {
			conn = DBHelper.getConn();
			String sql = "select b.* from ( select a.*,rownum as rid from tb_news a ) b where b.rid between "+start+" and "+end+"";
			ps = conn.prepareStatement(sql);
			rs = ps.executeQuery();
			while(rs.next()) {
				//获取分类编号rs.getInt("ntid");
				Theme theme = new ThemeDaoImpl().getThemeByTid(rs.getInt("ntid"));
				list.add(new News(rs.getInt("nid"), theme, rs.getString("ntitle"), rs.getString("nauthor"),
						rs.getString("nsummary"), rs.getString("ncontent"),
						rs.getString("nimage"), rs.getString("ndate"), rs.getInt("ncount")));
			}
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			DBHelper.myClose(conn, ps, rs);
		}
		return list;
	}
 
 
	@Override
	public int getNewsCount() {
		Connection conn = null;
		PreparedStatement ps = null;
		ResultSet rs = null;
		int count = 0;//保存表的总记录数
		try {
			conn = DBHelper.getConn();
			String sql = "select count(*) from tb_news";
			ps = conn.prepareStatement(sql);
			rs = ps.executeQuery();
			if(rs.next()) {
				count = rs.getInt(1);
			}
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			DBHelper.myClose(conn, ps, rs);
		}
		return count;
	
	}

二.携带模糊查询的分页

@Override
	public int getNewsCount(String strName) {
		Connection conn = null;
		PreparedStatement ps = null;
		ResultSet rs = null;
		int count = 0;//保存表的总记录数
		try {
			conn = DBHelper.getConn();
			String sql = "select count(*) from tb_news where ntitle like '%"+strName+"%'";
			ps = conn.prepareStatement(sql);
			rs = ps.executeQuery();
			if(rs.next()) {
				count = rs.getInt(1);
			}
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			DBHelper.myClose(conn, ps, rs);
		}
		return count;
	
	}
	
	
	
	@Override
	public List<News> queryNewsAll5(int pageIndex,int pageSize,String strName) {
		//根据参数pageIndex和pageSize来计算区间查询的规律
		int start = (pageIndex-1)*pageSize +1;
		int end = pageIndex * pageSize;
		
		Connection conn = null;
		PreparedStatement ps = null;
		ResultSet rs = null;
		List<News> list = new ArrayList<News>();
		try {
			conn = DBHelper.getConn();
			String sql = "select b.* from (\r\n" + 
					"       select a.*,rownum as rid from (\r\n" + 
					"               select * from tb_news where ntitle like '%"+strName+"%'\r\n" + 
					"        )a\r\n" + 
					")b where b.rid between "+start+" and "+end+"";
			ps = conn.prepareStatement(sql);
			rs = ps.executeQuery();
			while(rs.next()) {
				//获取分类编号rs.getInt("ntid");
				Theme theme = new ThemeDaoImpl().getThemeByTid(rs.getInt("ntid"));
				list.add(new News(rs.getInt("nid"), theme, rs.getString("ntitle"), rs.getString("nauthor"),
						rs.getString("nsummary"), rs.getString("ncontent"),
						rs.getString("nimage"), rs.getString("ndate"), rs.getInt("ncount")));
			}
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			DBHelper.myClose(conn, ps, rs);
		}
		return list;
	}

三.导入项目

<%	
						//request请求对象设置编码
						request.setCharacterEncoding("utf-8");
					
					
						//实例化DAO
						INewsDao ind = new NewsDaoImpl();
					
						//pageIndex  页码 默认第一页
						int pageIndex = 1;
						//pageSize  每页显示的条数  5条
						int pageSize = 5;
						
						//当手动点击了下一页按钮   获取pageIndex  赋值给第75处的那个pageINdex
						String pIndex = request.getParameter("pageIndex");
						if(null!=pIndex){//说明点击了下一页
							pageIndex = Integer.valueOf(pIndex);
						}
						
						
					
					
						//手动点击了搜索提交按钮   获取到模糊查询的关键字  否则没有点击的情况下  null  转换
						String strName = request.getParameter("strName");
						if(strName==null){//没有手动点击搜索
							strName="";
						}else{//手动点击了搜索
							//编码和解码
							//strName = new String(strName.getBytes("ISO-8859-1"),"utf-8");
						}
						System.out.println("strName = "+strName);
						//不考虑不糊查询
						int count = ind.getNewsCount(strName);//6  
						int pageMax = 0;
						if(count % pageSize == 0){
							pageMax = count / pageSize;
						}else{
							pageMax = count / pageSize +1;
						}
						System.out.println("count： "+count);
						System.out.println("pageMax： "+pageMax);
						
						
					
						
						//调用查看所有的新闻的方法
						List<News> listNews = ind.queryNewsAll5(pageIndex,pageSize,strName);//第一个参数页码  第二个参数：条数
						for(News news:listNews){
					%>
						<!-- 填充新闻标题以及时间或者作者 -->
						<li> 
							<!-- 新闻标题 -->
							<a href='#'><%=news.getNtitle() %></a> 
							<span> 
								作者：<%=news.getNauthor() %> 
								&#160;&#160;&#160;&#160; 
								<a href='#'>修改</a> 
								&#160;&#160;&#160;&#160; 
								<a href='javascript:void(0)' onclick='clickdel()'>删除</a>
							</span> </li>
					<%
						}
					%>
					
					<li class='space'></li>
					<p align="right" style = "font-size:20px;font-weight: bold"> 
						当前页数:[<%=pageIndex %>/<%=pageMax %>]&nbsp; 
						<a href="admin.jsp?pageIndex=1&strName=<%=null!=strName?strName:""%>">首页</a>
						<a href="admin.jsp?pageIndex=<%=pageIndex-1<0?1:pageIndex-1%>&strName=<%=null!=strName?strName:""%>">上一页</a>
						<a href="admin.jsp?pageIndex=<%=pageIndex+1>pageMax?pageMax:pageIndex+1%>&strName=<%=null!=strName?strName:""%>">下一页</a>
						<a href="admin.jsp?pageIndex=<%=pageMax%>&strName=<%=null!=strName?strName:""%>">末页</a> 
					</p>
				</ul>