JavaWeb分页实现

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一、项目结构

bean实体包，dao数据库操作包，webServlet包，utils工具包。

二、项目实现

1.实体：Ninja

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package pers.zx.bean;

public class Ninja {
	private Integer NinjaId;
    private String NinjaName;
    private String NinjaSex;
    private Integer NinjaAge;
    private String NinjaPassword;
    private String NinjaLevel;
    
	public Ninja() {
		// TODO Auto-generated constructor stub
	}
	public Ninja(Integer ninjaId, String ninjaName, String ninjaSex, Integer ninjaAge,
			String ninjaLevel) {
		NinjaId = ninjaId;
		NinjaName = ninjaName;
		NinjaSex = ninjaSex;
		NinjaAge = ninjaAge;
		NinjaLevel = ninjaLevel;
	}
	public String getNinjaName() {
		return NinjaName;
	}
	public void setNinjaName(String ninjaName) {
		NinjaName = ninjaName;
	}
	public String getNinjaSex() {
		return NinjaSex;
	}
	public void setNinjaSex(String ninjaSex) {
		NinjaSex = ninjaSex;
	}
	public String getNinjaPassword() {
		return NinjaPassword;
	}
	public void setNinjaPassword(String ninjaPassword) {
		NinjaPassword = ninjaPassword;
	}
	public String getNinjaLevel() {
		return NinjaLevel;
	}
	public void setNinjaLevel(String ninjaLevel) {
		NinjaLevel = ninjaLevel;
	}
	public Integer getNinjaAge() {
		return NinjaAge;
	}
	public void setNinjaAge(Integer ninjaAge) {
		NinjaAge = ninjaAge;
	}
	public Integer getNinjaId() {
		return NinjaId;
	}
	public void setNinjaId(Integer ninjaId) {
		NinjaId = ninjaId;
	}
	@Override
	public String toString() {
		// TODO Auto-generated method stub
		return NinjaId+" "+NinjaName+" "+NinjaSex+" "+NinjaAge+" "+NinjaLevel;
	}
}



2.Utils:数据库链接类以及关闭类

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package pers.zx.utils;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class JdbcConnection {
	  // 获取数据库连接
    public static Connection getConnection() {
        String url="jdbc:mysql://localhost:3306/h5_sql?allowMultiQueries=true&useUnicode=true&characterEncoding=utf8";
        String user="****";
        String password ="****";
        Connection connection = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        
        try {
            connection =  DriverManager.getConnection(url, user, password);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        
        return connection;
    }

}

#########################################################################
package pers.zx.utils;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class JdbcClose {
	protected Connection conn;
    protected PreparedStatement ps;
    protected ResultSet rs;
    
    public void close(){
        // 关闭资源
        try {
            if (rs!=null) {
                rs.close();
            }
            if (ps!=null) {
                ps.close();
            }
            if (conn!=null) {
                conn.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}



3.dao层：数据库相关操作

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package pers.zx.dao;

import java.util.List;

import pers.zx.bean.Ninja;

public interface NinjaDao {

	//根据每一页的条数 得到总页数
	public int pages(int rows);
	//根据所要查询的条数返回实体,从start开始查，查size条
	public List<Ninja> ninja(int start,int size);
}
#########################################################################
package pers.zx.dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import pers.zx.bean.Ninja;
import pers.zx.utils.JdbcClose;
import pers.zx.utils.JdbcConnection;

public class NinjaDaoImpl extends JdbcClose implements NinjaDao {

	protected Connection conn;
    protected PreparedStatement ps;
    protected ResultSet rs;
	@Override
	public int pages(int rows) {
		// TODO Auto-generated method stub
	  int num=0;
	  int page=0;//页数
	  conn=JdbcConnection.getConnection();
	  String sql="select COUNT(*) from ninja";
	  try {
		ps=conn.prepareStatement(sql);
		rs=ps.executeQuery();
		if(rs.next()) {
			num=rs.getInt(1);//获取总数
		}
		 if(num%rows==0) {
			  page=num/rows;
		  }else {
			  page=num/rows+1;
		  }
	} catch (SQLException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	}finally {
		super.close();//关闭资源
	}
	  
		return page;
	}

	@Override
	public List<Ninja> ninja(int start, int size) {
		// TODO Auto-generated method stub
		List<Ninja> list=new ArrayList<Ninja>();//创建集合
		 conn=JdbcConnection.getConnection();
		  String sql = "SELECT NinjaId,NinjaName,NinjaAge,NinjaSex,NinjaLevel FROM ninja LIMIT ?,?";//limit限制从start开始取size
		  try {
			ps=conn.prepareStatement(sql);
			//设置相关参数,在数据库中从start开始取size个
            ps.setInt(1, start);
            ps.setInt(2,size);
            rs = ps.executeQuery();
            while(rs.next()){
               Ninja ninja = new Ninja();
               ninja.setNinjaId(rs.getInt("NinjaId"));
               ninja.setNinjaName(rs.getString("NinjaName"));
               ninja.setNinjaAge(rs.getInt("NinjaAge"));
               ninja.setNinjaSex(rs.getString("NinjaSex"));
               ninja.setNinjaLevel(rs.getString("NinjaLevel"));
               list.add(ninja);
            }
            

		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {
			super.close();
		}
		return list;
	}

}



4.web层Servlet实现

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package pers.zx.web;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import pers.zx.dao.NinjaDao;
import pers.zx.dao.NinjaDaoImpl;

/**
 * Servlet implementation class PageServlet
 */
@WebServlet("/PageServlet")
public class PageServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public PageServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		int rows=5;//一页显示条信息
		int pageNos;//页号
		int countPage;
		NinjaDao list=new NinjaDaoImpl();
		countPage=list.pages(rows);//总页数
		
		HttpSession session = request.getSession(); // 将数据存到session中以便于在前台获取
		
        session.setAttribute("countPage", countPage);
	    if (request.getParameter("pageNos") == null|| Integer.parseInt(request.getParameter("pageNos"))<1) {
	    	pageNos = 1;
           session.setAttribute("NinjaList", list.ninja(0, rows));
           //当前页数
           session.setAttribute("pageNos", pageNos);
        } else {
        	pageNos = Integer.parseInt(request.getParameter("pageNos"));
            session.setAttribute("NinjaList",list.ninja((pageNos-1)*rows, rows));
            //当前页数
            session.setAttribute("pageNos", pageNos);
        }
        request.getRequestDispatcher("page.jsp").forward(request, response);
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}



5.page.jsp

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<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>分页</title>
</head>
<body>
<form action="PageServlet">
<center>
 <table>
        <tr>
            <th>NinjaId</th>
            <th>NinjaName</th>
            <th>NinjaAge</th>
            <th>NinjaSex</th>
            <th>NinjaLevel</th>
        </tr>
<c:forEach items="${NinjaList}" var="ninja" >
            <tr>
                <td>${ninja.ninjaId }</td>
                <td>${ninja.ninjaName }</td>
                <td>${ninja.ninjaAge}</td>
                <td>${ninja.ninjaSex}</td>
                <td>${ninja.ninjaLevel}</td>
            </tr>
       
    </c:forEach>
    
 </table>   
</center>
    <center>
<a href="PageServlet?pageNos=1" >首页</a>
<c:choose>
<c:when test="${pageNos==1}">
<a href="PageServlet?pageNos=${pageNos}">上一页</a>
</c:when>
<c:otherwise>
<a href="PageServlet?pageNos=${pageNos-1}">上一页</a>
</c:otherwise>
</c:choose>
<c:choose>
<c:when test="${pageNos==countPage}">
<a href="PageServlet?pageNos=${countPage }">下一页</a>
</c:when>
<c:otherwise>
<a href="PageServlet?pageNos=${pageNos+1 }">下一页</a>
</c:otherwise>
</c:choose>
<a href="PageServlet?pageNos=${countPage }">末页</a>
</center>

<h4 align="center">共${countPage}页  
<input type="text" value="${pageNos}" name="pageNos" size="1">页
<input type="submit" value="go">
</h4>
</form>
</body>
</html>



6.index.jsp

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<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<% response.sendRedirect("PageServlet"); %>
</body>
</html>

7.web.xml

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<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>Page</display-name>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

三、结果显示

四、总结

算是初次尝试分页，通过网上的代码，自己稍作修改，实现了一个简单的分页web程序。还需很多改进，比如：
1.应该把分页操作专门做一个工具类而不是放在dao层
2.还有很多细节要处理，让其复用性更好
总之，通过这次尝试感觉还是很有收获的。

注:

  • 如有不正确还请见谅。
  • 如需代码请访问我的github
  • 另外，我做了一些关于Spring、Struts、Hibernate的小应用可以帮助理解这些框架，如需代码请访问我的Github：https://github.com/Zxnaruto
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      categories: false
      tags: true

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