Web--简单实现分页查询

Dear 丶 2021-08-13 22:35 464阅读 0赞

#### 建表及准备数据 ####

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70]

#### 创建实体类User： ####

package pers.zhang.domain;
    
    public class User { 
    	
    	private Long user_id;
    	private String user_code;
    	private String user_name;
    	private String user_password;
    	private String user_state;
    	public Long getUser_id() { 
    		return user_id;
    	}
    	public void setUser_id(Long user_id) { 
    		this.user_id = user_id;
    	}
    	public String getUser_code() { 
    		return user_code;
    	}
    	public void setUser_code(String user_code) { 
    		this.user_code = user_code;
    	}
    	public String getUser_name() { 
    		return user_name;
    	}
    	public void setUser_name(String user_name) { 
    		this.user_name = user_name;
    	}
    	public String getUser_password() { 
    		return user_password;
    	}
    	public void setUser_password(String user_password) { 
    		this.user_password = user_password;
    	}
    	public String getUser_state() { 
    		return user_state;
    	}
    	public void setUser_state(String user_state) { 
    		this.user_state = user_state;
    	}
    }

#### 配置Hibernate元数据User.hbm.xml ####

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
    <hibernate-mapping package="pers.zhang.domain" >
    	<class name="User" table="sys_user" >
    		<id name="user_id" >
    			<generator class="identity"></generator>
    		</id>
    		<property name="user_code" column="user_code" ></property>
    		<property name="user_name" column="user_name" ></property>
    		<property name="user_password" column="user_password" ></property>
    		<property name="user_state" column="user_state" ></property>
    	</class>
    </hibernate-mapping>

#### PageBean： ####

package pers.zhang.domain;
    
    import java.util.ArrayList;
    import java.util.List;
    
    public class PageBean<T> { 
    
    	//每页需要显示的数据
    	private List<T> userList = new ArrayList<T>();
    	
    	//总页数
    	private int totalPage;
    	
    	//当前页
    	private int currentPage;
    	
    	//总条数
    	private int totalCount;
    	
    	//当前页显示条数
    	private int currentCount;
    
    	public List<T> getUserList() { 
    		return userList;
    	}
    
    	public void setUserList(List<T> userList) { 
    		this.userList = userList;
    	}
    
    	public int getTotalPage() { 
    		return totalPage;
    	}
    
    	public void setTotalPage(int totalPage) { 
    		this.totalPage = totalPage;
    	}
    
    	public int getCurrentPage() { 
    		return currentPage;
    	}
    
    	public void setCurrentPage(int currentPage) { 
    		this.currentPage = currentPage;
    	}
    
    	public int getTotalCount() { 
    		return totalCount;
    	}
    
    	public void setTotalCount(int totalCount) { 
    		this.totalCount = totalCount;
    	}
    
    	public int getCurrentCount() { 
    		return currentCount;
    	}
    
    	public void setCurrentCount(int currentCount) { 
    		this.currentCount = currentCount;
    	}
    }

#### 控制层： ####

package pers.zhang.servlet;
    
    import java.io.IOException;
    import java.sql.SQLException;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    import pers.zhang.domain.PageBean;
    import pers.zhang.domain.User;
    import pers.zhang.service.UserService;
    
    
    public class FindAllUserServlet extends HttpServlet { 
    	private static final long serialVersionUID = 1L;
           
     
    	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
    		doPost(request, response);
    	}
    
    
    	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
    			
    		UserService userService = new UserService();
    		PageBean<User> pageBean = null;
    		
    		
    		//获取当前是第几页
    		String currentPageStr = request.getParameter("currentPage");
    		//如果为null，则是第一次访问，赋值1
    		if(currentPageStr == null) { 
    			currentPageStr = "1";
    		}
    		int currentPage = Integer.parseInt(currentPageStr);
    		
    		//每页显示6条
    		int currentCount = 6;
    		
    		try { 
    			//获取pageBean
    			pageBean = userService.findPageBean(currentPage,currentCount);
    		} catch (SQLException e) { 
    			e.printStackTrace();
    		}
    		
    		request.setAttribute("pageBean", pageBean);
    		request.getRequestDispatcher("list.jsp").forward(request, response);
    	}
    
    }

#### Service层： ####

package pers.zhang.service;
    
    import java.sql.SQLException;
    import java.util.List;
    
    import pers.zhang.dao.UserDao;
    import pers.zhang.domain.PageBean;
    import pers.zhang.domain.User;
    
    public class UserService { 
    
    	
    	//封装pageBean并返回
    	public PageBean findPageBean(int currentPage, int currentCount) throws SQLException{ 
    		UserDao userDao = new UserDao();
    		//获取总条数
    		int totalCount = userDao.getUserCount();
    		
    		
    		PageBean pageBean = new PageBean();
    		
    		//当前页
    		pageBean.setCurrentPage(currentPage);
    		//每页显示条数
    		pageBean.setCurrentCount(currentCount);
    		//总条数
    		pageBean.setTotalCount(totalCount);
    		//总页数
    		pageBean.setTotalPage((int)(Math.ceil(1.0 * totalCount / currentCount)));
    		//每页显示的数据
    		int index = (currentPage - 1) * currentCount;//index为查询开始位置=（当前页-1）*每页显示条数
    		List<User> list = userDao.findUserListForPageBean(index, currentCount);
    		pageBean.setUserList(list);
    		
    		return pageBean;
    	}
    }

#### Dao层： ####

package pers.zhang.dao;
    
    import java.util.List;
    
    import org.hibernate.Criteria;
    import org.hibernate.Session;
    import org.hibernate.Transaction;
    import org.hibernate.criterion.Projections;
    
    import pers.zhang.domain.User;
    import pers.zhang.utils.HibernateUtils;
    
    public class UserDao { 
    
    
    	//获取总条数
    	public int getUserCount() { 
    		Session session = HibernateUtils.openSession();
    		Transaction tx = session.beginTransaction();
    
    		Criteria criteria = session.createCriteria(User.class);
    		//设置查询的聚合函数 => 总行数
    		criteria.setProjection(Projections.rowCount());
    		Long count = (Long) criteria.uniqueResult();
    		tx.commit();
    		session.close();
    		return count.intValue();
    	}
    	
    	
    	//分页查询
    	public List<User> findUserListForPageBean(int index, int currentCount) { 
    		
    		Session session = HibernateUtils.openSession();
    		Transaction tx = session.beginTransaction();
    
    		Criteria criteria = session.createCriteria(User.class);
    		//设置分页信息 limit ?,? 
    		criteria.setFirstResult(index);
    		criteria.setMaxResults(currentCount);
    		List<User> list = criteria.list();
    
    		tx.commit();
    		session.close();
    		return list;
    	}
    }

#### 前端页面： ####

<%@ page language="java" contentType="text/html; charset=utf-8"
        pageEncoding="utf-8"%>
    <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
    <!DOCTYPE html>
    <html>
    	<head>
    		<meta charset="UTF-8">
    		<title></title>
    		<script type="text/javascript" src="js/jquery-2.1.0.js" ></script>
    		<script type="text/javascript" src="js/bootstrap.min.js" ></script>
    		<link rel="stylesheet" href="css/bootstrap.css" />
    	</head>
    	<body>
    		<div style="text-align: center; width: 600px;">
    		<table class="table table-hover">
    		  <tr><td>编号</td><td>用戶ID</td><td>用户名</td><td>昵称</td><td>密码</td></tr>
    		  
    		  <c:forEach items="${pageBean.userList }" var="list">
    		  	<tr><td>${list.user_id }</td><td>${list.user_code }</td><td>${list.user_name }</td><td>${list.user_password }</td><td>${list.user_state }</td></tr>
    		  </c:forEach>
    		  <tr><td colspan="5">
    		  	<div>
    		  		<ul class="pagination">
    		  			
    		  			<c:if test="${pageBean.currentPage == 1 }">
    		  				<li class="disabled"><a href="${pageContext.request.contextPath }/findUser?currentPage=${pageBean.currentPage-1}">«</a></li>
    		  			</c:if>
    		  			<c:if test="${pageBean.currentPage != 1 }">
    		  				<li><a href="${pageContext.request.contextPath }/findUser?currentPage=${pageBean.currentPage-1}">«</a></li>
    		  			</c:if>
    		  			
    		  			<c:forEach begin="1" end="${pageBean.totalPage }" var="page">
    		  				
    		  				<c:if test="${pageBean.currentPage == page }">
    		  					<li class="active"><a href="javascript:void(0);">${page }</a></li>
    		  				</c:if>
    		  				<c:if test="${pageBean.currentPage != page }">
    		  					<li><a href="${pageContext.request.contextPath }/findUser?currentPage=${page}">${page }</a></li>
    		  				</c:if>
    		  				
    		  			</c:forEach>
    		  			
    		  			<c:if test="${pageBean.currentPage != pageBean.totalPage }">
    		  				<li><a href="${pageContext.request.contextPath }/findUser?currentPage=${pageBean.currentPage+1}">»</a></li>
    		  			</c:if>
    		  			<c:if test="${pageBean.currentPage == pageBean.totalPage }">
    		  				<li class="disabled"><a href="${pageContext.request.contextPath }/findUser?currentPage=${pageBean.currentPage+1}">»</a></li>
    		  			</c:if>
    				</ul>
    		  	</div>
    		  	</td>
    		  </tr>
    		</table>
    	</div>
    
    
    	</body>
    </html>

#### 测试： ####

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