简单分页查询(web基础学习笔记十三)

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