简单分页查询(web基础学习笔记十三)

2023-07-16 17:53:45

一、建立资源文件和工具类

1.1 、database.properties

jdbc.driver_class=oracle.jdbc.driver.OracleDriver

jdbc.connection.url=jdbc:oracle:thin:@localhost:1521:orcl

jdbc.connection.username=scott

jdbc.connection.password=tiger

1.2、建立包：com.pb.emp.untily

ConfigManager类

package com.pb.emp.untily;

import java.io.IOException;

import java.io.InputStream;

import java.util.Properties;

public class ConfigManager {

    private static ConfigManager configManager;

    private static Properties properties;

    private ConfigManager(){

        String configfile="database.properties";

        properties=new Properties();

        InputStream in=ConfigManager.class.getClassLoader().getResourceAsStream(configfile);

        try {

            properties.load(in);

            in.close();

        } catch (IOException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }

    }

    public static ConfigManager getInstance(){

        if(configManager==null){

            configManager=new ConfigManager();

        }

        return configManager;

    }

    public static String getString(String key){

        return properties.getProperty(key);

    }

}

1.3、建立员工实体类

package com.pb.emp.entity;

import java.util.Date;

/**

 * 员工实体类

 * @author 森林森

 *

 */

public class Emp {

    private int empno;

    private String ename;

    private String job;

    private int mgr;

    private Date hiredate;

    private double sal;

    private double comm;

    private int deptno;

    //getter和setter方法

    public int getEmpno() {

        return empno;

    }

    public void setEmpno(int empno) {

        this.empno = empno;

    }

    public String getEname() {

        return ename;

    }

    public void setEname(String ename) {

        this.ename = ename;

    }

    public String getJob() {

        return job;

    }

    public void setJob(String job) {

        this.job = job;

    }

    public int getMgr() {

        return mgr;

    }

    public void setMgr(int mgr) {

        this.mgr = mgr;

    }

    public Date getHiredate() {

        return hiredate;

    }

    public void setHiredate(Date hiredate) {

        this.hiredate = hiredate;

    }

    public double getSal() {

        return sal;

    }

    public void setSal(double sal) {

        this.sal = sal;

    }

    public double getComm() {

        return comm;

    }

    public void setComm(double comm) {

        this.comm = comm;

    }

    public int getDeptno() {

        return deptno;

    }

    public void setDeptno(int deptno) {

        this.deptno = deptno;

    }

}

二、建立BaseDao基类

2.1、建立基类

package com.pb.emp.dao;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import com.pb.emp.untily.ConfigManager;

public class BaseDao {

    protected Connection conn;

    protected PreparedStatement ps;

    protected ResultSet rs;

    //建立连接

    public boolean getConnection(){

        String driver=ConfigManager.getInstance().getString("jdbc.driver_class");

        String url=ConfigManager.getInstance().getString("jdbc.connection.url");

        String username=ConfigManager.getInstance().getString("jdbc.connection.username");

        String password=ConfigManager.getInstance().getString("jdbc.connection.password");

        try {

            Class.forName(driver);

            conn=DriverManager.getConnection(url,username, password);

        } catch (ClassNotFoundException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

            return false;

        } catch (SQLException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

            return false;

        }

        return true;

    }

    //增加，修改，删除

    public int executeUpdate(String sql, Object[] params){

        getConnection();

        int updateRow=0;

        try {

            ps=conn.prepareStatement(sql);

            //填充占位符

            for(int i=0;i<params.length;i++){

                ps.setObject(i+1, params[i]);

            }

            updateRow = ps.executeUpdate();

        } catch (SQLException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }

        return updateRow;

    }

    //

    //查询

        public ResultSet executeSQL(String sql, Object[] params){

            getConnection();

            try {

                ps=conn.prepareStatement(sql);

                //填充占位符

                for(int i=0;i<params.length;i++){

                    ps.setObject(i+1, params[i]);

                }

                rs = ps.executeQuery();

            } catch (SQLException e) {

                // TODO Auto-generated catch block

                e.printStackTrace();

            }

            return rs;

        }

    // 关闭资源

        public boolean closeResource() {

            if(rs!=null){

                try {

                    rs.close();

                } catch (SQLException e) {

                    // TODO Auto-generated catch block

                    e.printStackTrace();

                    return false;

                }

            }

            if(ps!=null){

                try {

                    ps.close();

                } catch (SQLException e) {

                    // TODO Auto-generated catch block

                    e.printStackTrace();

                    return false;

                }

            }

            if(conn!=null){

                try {

                    conn.close();

                } catch (SQLException e) {

                    // TODO Auto-generated catch block

                    e.printStackTrace();

                    return false;

                }

            }

            return true;

        }

}

2.2、建立分页类

package com.pb.emp.untily;

public class Page {

    private int currPageNo=1;  //当前页号

    private int pageSize=0; //每页显示的记录数

    private int recordCount=0; //总记录数

    private int totalPageCount=1; //总页数

    public int getCurrPageNo() {

        //条中不能加this

        if(totalPageCount==0)

            return 0;

        return currPageNo;

    }

    public void setCurrPageNo(int currPageNo) {

        if(currPageNo>0)

        this.currPageNo = currPageNo;

    }

    public void setPageSize(int pageSize) {

        //条中不能加this

        if(pageSize>0)

        this.pageSize = pageSize;

    }

    public int getPageSize() {

        return pageSize;

    }

    public int getTotalPageCount() {

        return totalPageCount;

    }

    public void setTotalPageCount(int totalPageCount) {

        this.totalPageCount = totalPageCount;

    }

    public int getRecordCount() {

        return recordCount;

    }

    public void setRecordCount(int recordCount) {

        //条中不能加this

        if(recordCount>0)

        this.recordCount = recordCount;

        //调用总页数设置方法为totalPageCount赋值

        //this.settotalPageCountByRs();

    }

    //设置总页数

    public int settotalPageCountByRs(){

        if(this.recordCount%this.pageSize==0){

            this.totalPageCount=this.recordCount/this.pageSize;

        }else if(this.recordCount%this.pageSize>0){

            this.totalPageCount=this.recordCount/this.pageSize+1;

    }else{

        this.totalPageCount=0;

        }

        return this.totalPageCount;

    }

   //开始记录数

    public int getStartRow(){

        return (currPageNo-1) * pageSize+1;

    }

      //结束记录数

    public int  getEndRow(){

        return currPageNo * pageSize;

    }

    public static void main(String[] args) {

        Page p=new Page();

        p.setCurrPageNo(2);

        System.out.println(p.getCurrPageNo());

        p.setPageSize(3);

        System.out.println(p.getPageSize());

        int i=p.getStartRow();

        System.out.println("启始记录"+i);

        int j=p.getEndRow();

        System.out.println("结束记录"+j);

    }

}

三、建立分页查询的实现类

3.1、实现类

package com.pb.emp.dao.empl;

import java.sql.SQLException;

import java.util.ArrayList;

import java.util.Date;

import java.util.List;

import com.pb.emp.dao.BaseDao;

import com.pb.emp.dao.EmpDao;

import com.pb.emp.entity.Emp;

import com.pb.emp.untily.Page;

public class EmpDaoImpl extends BaseDao implements EmpDao {

    /**

     * 获取新闻总数量

     * */

    public int getTotalCount() {

        int totalCount=0;

        String sql="select count(*) from emp";

        Object[] params={};

         rs=this.executeSQL(sql, params);

        try {

            while(rs.next()){

                totalCount=rs.getInt(1);

            }

        } catch (SQLException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }finally{

            this.closeResource();

        }

        return totalCount;

    }

    /**

     * 分页获取新闻信息

     * */

    public List<Emp> getEmpByPage(int pageNo, int pageSize) {

        // 建立集合存放查询结果

        List<Emp> emplist = new ArrayList<Emp>();

        String sql = "SELECT empno,ename,job,mgr,hiredate,sal,comm,deptno FROM(SELECT empno,ename,job,mgr,hiredate,sal,comm,deptno,ROWNUM rn FROM emp) e WHERE e.rn BETWEEN ? AND ?";

        Page pages=new Page();

        //设置当前页和页显示显示记录数

        pages.setCurrPageNo(pageNo); //设置当前页码

        pages.setPageSize(pageSize); //每页显示记录数

        //计算开始和结束记录数

        int startRow = pages.getStartRow();

        int endRow = pages.getEndRow();

        //填充占位符?

        Object [] params={startRow,endRow};

        //调用类BaseDao的查询方法并接收结果

        rs=this.executeSQL(sql, params);

        try {

            while(rs.next()){

                 int empno=rs.getInt("empno");

                 String ename=rs.getString("ename");

                 String job=rs.getString("job");

                 int mgr=rs.getInt("mgr");

                 Date hiredate=rs.getDate("hiredate");

                 double sal=rs.getDouble("sal");

                 double comm=rs.getDouble("comm");

                 int deptno=rs.getInt("deptno");

                 //声明Emp对象

                 Emp emp=new Emp();

                 //将得到的值添加到对象中

                 emp.setEmpno(empno);

                 emp.setEname(ename);

                 emp.setJob(job);

                 emp.setMgr(mgr);

                 emp.setHiredate(hiredate);

                 emp.setSal(sal);

                 emp.setComm(comm);

                 emp.setDeptno(deptno);

                 //将对象添加到集合

                 emplist.add(emp);

            }

        } catch (SQLException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }finally{

            this.closeResource();

        }

        return emplist;

    }

    public static void main(String[] args) {

        EmpDaoImpl  e=new EmpDaoImpl();

        System.out.println(e.getTotalCount());

        List<Emp> emplist=e.getEmpByPage(2, 3);

        System.out.println("=====员工信息====");

        for (Emp emp : emplist) {

            System.out.println(emp.getSal()+"\t"+emp.getComm()+"\t"+emp.getDeptno() );

        }

    }

}

3.2、分离出接口

package com.pb.emp.dao;

import java.util.List;

import com.pb.emp.entity.Emp;

public interface EmpDao {

    /**

     * 获取新闻总数量

     * */

    public int getTotalCount();

    public List<Emp> getEmpByPage(int pageNo, int pageSize);

}

3.3、分享出service接口和实现类

package com.pb.service;

import java.util.List;

import com.pb.emp.entity.Emp;

public interface Service {

    public List<Emp> getEmpByPage(int pageNo, int pageSize);

    public int getTotalCount();

}
package com.pb.service.impl;

import java.util.List;

import com.pb.emp.dao.EmpDao;

import com.pb.emp.entity.Emp;

import com.pb.service.Service;

public class ServiceImpl implements Service {

      private EmpDao empDao;

   /**

    * 一定要加setter和getter方法，不然无法调用

    * @森林森

    */

    public EmpDao getEmpDao() {

        return empDao;

    }

    public void setEmpDao(EmpDao empDao) {

        this.empDao = empDao;

    }

    @Override

    public List<Emp> getEmpByPage(int pageNo, int pageSize) {

        return empDao.getEmpByPage(pageNo, pageSize);

    }

    @Override

    public int getTotalCount() {

        // TODO Auto-generated method stub

        return empDao.getTotalCount();

    }

}

四、建立页面

4.1导入service类

建立common.jsp页面

<jsp:useBean id="empService" class="com.pb.service.impl.ServiceImpl" scope="page"></jsp:useBean>

<jsp:useBean id="empDao" class="com.pb.emp.dao.empl.EmpDaoImpl" scope="page"></jsp:useBean>

<jsp:setProperty property="empDao" name="empService" value="<%=empDao%>" />

4.2 实现页面get方式

<%@page import="com.pb.emp.untily.Page"%>

<%@page import="com.pb.emp.entity.Emp"%>

<%@page import="java.util.List"%>

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<%@include file="../common/common.jsp" %>

<!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>Insert title here</title>

<script type="text/javascript">

function go(){

    var goid=document.getElementById("goid").value;

    var regexp=/^\d+$/;

    if(!regexp.test(goid)){

        alert("请输入数字");

    }else{

        window.location="emp.jsp?pageIndex="+goid;

    }

}

</script>

</head>

<body>

<table border="1" width="80%" align="center">

<tr>

<td>员工编号</td>

<td>员工姓名</td>

<td>职位</td>

<td>入职日期</td>

<td>工资</td>

<td>奖金</td>

<td>部门编号</td>

</tr>

<%

request.setCharacterEncoding("utf-8");

int pageSize=5;

String currPageno=request.getParameter("pageIndex");

if(currPageno==null){

    currPageno="1";

}

//当前页

int pageNo=Integer.parseInt(currPageno);

//总记录娄

int recordCount=empService.getTotalCount();

//每页显示记录数

Page pages=new Page();

//当前页

pages.setCurrPageNo(pageNo);

//页面显示多少条记录

pages.setPageSize(pageSize);

//总记录数

pages.setRecordCount(recordCount);

//总页数

int totalPageCount=pages.settotalPageCountByRs();

//对首面和最后一面设置不重小于1和大于最后一页

if(pageNo<1){

    pageNo=1;

}else if (pageNo>totalPageCount){

    pageNo=totalPageCount;

}

 List<Emp> emplist=empService.getEmpByPage(pageNo, pageSize);

 for(Emp emp:emplist){

%>

<tr>

<td><%=emp.getEmpno() %></td>

<td><%=emp.getEname() %></td>

<td><%=emp.getJob() %></td>

<td><%=emp.getHiredate() %></td>

<td><%=emp.getSal() %></td>

<td><%=emp.getComm() %></td>

<td><%=emp.getDeptno() %></td>

</tr>

<%

 }

%>

<tr>

<td>共<%=recordCount %>条记录&nbsp;&nbsp; <%=pageNo %>/<%=totalPageCount %>页</td>

<% //控制首页的显示

if(pageNo>1){

%>

<td><a href="emp.jsp?pageIndex=1">首页</a></td>

<td><a href="emp.jsp?pageIndex=<%=pageNo-1%>">上一页</a></td>

<%

}

if(pageNo<totalPageCount){

    //控制最后一页的显示

%>

<td><a href="emp.jsp?pageIndex=<%=pageNo+1%>">下一页</a></td>

<td><a href="emp.jsp?pageIndex=<%=totalPageCount%>">最后一页</a></td>

<%

}

%>

<td><input type="text" id="goid" name="goid"> </td>

<td><a href="javascript:go();">GO</a></td>

</tr>

</table>

</body>

</html>

4.3 实现页面Post方式

小弟没持明白，搞明白了再写

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