记录学习的脚步
使用jdbc方式连接oracle数据库,然后分页显示scott用户的emp表中的记录
其中 让人比较费劲的就是oracle的分页查询 需要用到子查询和rownum
rownum是按记录的插入顺序生成的行编号,默认情况下为1,所以只有进行小于操作的时候,rownum才有意义
而对于rownum的详细详解 参看这位老兄写的 http://www.cnblogs.com/zjrstar/archive/2006/08/31/491090.html
index.jsp的代码
<%@page import="com.undergrowth.EmpBean"%>
<%@page import="java.sql.ResultSet"%>
<%@page import="java.sql.PreparedStatement"%>
<%@page import="com.undergrowth.ConnDB"%>
<%@page import="java.sql.Connection"%>
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<center>
<%
int pageNow=1;
String s_pageNow=request.getParameter("pageNow");
if(s_pageNow!=null) pageNow=Integer.parseInt(s_pageNow);
int pageSize=3; //每一页显示多少条记录
int rowCount=ConnDB.getRowCount(); //总共有多少行
int pageCount=0; //总共有多少页
//获取总共有多少页
if(rowCount%pageSize==0) {
pageCount=rowCount/pageSize;
}else {
pageCount=rowCount/pageSize+1;
}
ArrayList<EmpBean> alBeans=ConnDB.getAllRecord(pageNow,pageSize);
if(alBeans.size()>0){
out.print("<table align='center' border=1>"+
"<caption>雇员信息表</caption>"+"<tr><th>编号</th><th>姓名</th><th>工作</th><th>领导</th><th>雇佣日期</th><th>薪水</th><th>补贴</th><th>部门编号</th></tr>");
//显示记录
for(EmpBean bean:alBeans)
{
out.print("<tr>");
out.print("<td>"+bean.getEmpno()+"</td>");
out.print("<td>"+bean.getEname()+"</td>");
out.print("<td>"+bean.getJob()+"</td>");
out.print("<td>"+bean.getMgr()+"</td>");
out.print("<td>"+bean.getHiredate()+"</td>");
out.print("<td>"+bean.getSal()+"</td>");
out.print("<td>"+bean.getComm()+"</td>");
out.print("<td>"+bean.getDeptno()+"</td>");
out.print("</tr>");
}
out.print("<tr align='center'>");
out.print("<td colspan=8>");
//显示上一页
if(pageNow!=1) out.print("[<a href=index.jsp?pageNow="+(pageNow-1)+">上一页</a>]");
for(int i=1;i<=pageCount;i++)
{
out.print("[<a href=index.jsp?pageNow="+i+">"+i+"</a>]");
}
//显示下一页
if(pageNow!=pageCount) out.print("[<a href=index.jsp?pageNow="+(pageNow+1)+">下一页</a>]");
out.print("</td>");
out.print("</tr>");
out.print("</table>");
}
%>
</center>
</body>
</html>
用于连接数据库的ConnDB.java
package com.undergrowth;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
public class ConnDB {
private static String driverName="oracle.jdbc.driver.OracleDriver";
private static String url="jdbc:oracle:thin:@localhost:1521:under";
private static String user="scott";
private static String password="scott";
private static Connection connection=null;
private static PreparedStatement ps=null;
private static ResultSet rs=null;
public static Connection getConnection()
{
try {
//注册驱动
Class.forName(driverName);
//建立连接
connection=DriverManager.getConnection(url, user, password);
} catch (Exception e) {
e.printStackTrace();
}
return connection;
}
public static int getRowCount()
{
int rowCount=0;
connection=getConnection();
//获取到员工表中有多少条记录
String sql="select count(*) from emp";
try {
ps = connection.prepareStatement(sql);
rs=ps.executeQuery();
if(rs.next()){
rowCount=Integer.parseInt(rs.getString(1));
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
closeRes(rs, ps, connection);
}
return rowCount;
}
public static ArrayList<EmpBean> getAllRecord(int pageNow,int pageSize)
{
ArrayList<EmpBean> alBeans=new ArrayList<EmpBean>();
try {
connection=getConnection();
//String sql="select * from emp where rownum<="+pageNow*pageSize + "and rownum>="+(pageNow-1)*pageSize+1;
String sql="select a2.* from (select a1.*,rownum rn from (select * from emp) a1 where rownum<="+pageNow*pageSize+") a2 where a2.rn>="+((pageNow-1)*pageSize+1);
//System.out.println(sql);
ps=connection.prepareStatement(sql);
rs=ps.executeQuery();
while(rs.next())
{
EmpBean empBean=new EmpBean();
empBean.setEmpno(rs.getString(1));
empBean.setEname(rs.getString(2));
empBean.setJob(rs.getString(3));
empBean.setMgr(rs.getString(4));
empBean.setHiredate(rs.getDate(5));
empBean.setSal(rs.getFloat(6));
empBean.setComm(rs.getFloat(7));
empBean.setDeptno(rs.getString(8));
alBeans.add(empBean);
}
} catch (Exception e) {
// TODO: handle exception
}
return alBeans;
}
public static void closeRes(ResultSet rs,PreparedStatement ps,Connection connection)
{
if(rs!=null)
try {
rs.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
if(ps!=null)
try {
ps.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
if(connection!=null)
try {
connection.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
辅助Bean EmpBean.java
package com.undergrowth;
import java.util.Date;
public class EmpBean {
private String empno;
public String getEmpno() {
return empno;
}
public void setEmpno(String 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 String getMgr() {
return mgr;
}
public void setMgr(String mgr) {
this.mgr = mgr;
}
public Date getHiredate() {
return hiredate;
}
public void setHiredate(Date hiredate) {
this.hiredate = hiredate;
}
public Float getSal() {
return sal;
}
public void setSal(Float sal) {
this.sal = sal;
}
public Float getComm() {
return comm;
}
public void setComm(Float comm) {
this.comm = comm;
}
public String getDeptno() {
return deptno;
}
public void setDeptno(String deptno) {
this.deptno = deptno;
}
private String ename;
private String job;
private String mgr;
private Date hiredate;
private Float sal;
private Float comm;
private String deptno;
}
测试效果
输入: http://localhost:8080/PagingOracle/
效果:
