Oracle 高效分页技术 根据ROWNUM分页

/**

* 这个分页比较高较，项目中的数据是上千万级的数量级

* 当然了，我的数据库用了索引，where 条件中根据索引来查询是很快的哦，索引怎么用就不在本章的讨论范围之内了

* 核心SQL语句是：SELECT * FROM (SELECT SUB_TAB.*, ROWNUM RN FROM (your_sql) SUB_TAB WHERE ROWNUM <= 20) WHERE RN >= 1

* DataSource.java：获取数据库的链接

* GlobalConst.java：定义全局变量

* Page.java：分页的核心java bean

* PageTest.java：一个测试类

* jdbc.properties：jdbc的配置文件

*/

/*

* @author Sugar.Tan<br>

*/

package common;

import java.sql.Connection;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import java.util.List;

/**

* pageSize, pageCount, hasNextPage, hasPreviousPage<br>

* rule: the value of -1 is last page; 1 is the first page.

*/

public class Page {

private int pageSize; //一页显示的记录数

private int pageCount; //总页数

private boolean hasNextPage; //是否有下一页

private boolean hasPrePage; //是否有上一页

private int curPage = 1; //待显示的页面

private int tolCount; //总记录数量

@SuppressWarnings("unchecked")

private List dataList;

private int startRow = 0;

private int endRow = 10;

private void calPreNext() {

//this.hasNextPage = curPage == pageCount ? false : true;

this.hasNextPage = (pageCount == 0 ||curPage == pageCount) ? false : true;

this.hasPrePage = (curPage > 1) ? true : false;

}

private void calPage() {

pageCount = (tolCount + pageSize - 1) / pageSize;

}

private void calStartEnd () {

startRow = pageSize * (curPage - 1) + 1; //1

endRow = pageSize * curPage; //10

}

private void volidate() {

if (curPage == -1 || curPage > pageCount) curPage = pageCount;

if (curPage == 0 || curPage < -1) curPage = 1;

}

public void cal() {

calPage();

volidate();

calStartEnd();

calPreNext();

}

public int getTolCount() {

return tolCount;

}

public int getStartRow() {

return startRow;

}

public int getEndRow() {

return endRow;

}

public void setEndRow(int endRow) {

this.endRow = endRow;

}

public void setTolCount(int tolCount) {

this.tolCount = tolCount;

this.cal();

}

public boolean isHasPrePage() {

return hasPrePage;

}

@SuppressWarnings("unchecked")

public List getDataList() {

return dataList;

}

@SuppressWarnings("unchecked")

public void setDataList(List dataList) {

this.dataList = dataList;

}

/**

* 构造方法

*/

public Page(int curPage) {

this.pageSize = 10; //初始设置一页的记录数

this.hasNextPage = false; //初始

this.hasPrePage = false; //初始

this.curPage = curPage;

}

public Page(){}

public int getPageSize() {

return pageSize;

}

public void setPageSize(int pageSize) {

this.pageSize = pageSize;

}

public int getPageCount() {

return pageCount;

}

public void setPageCount(int pageCount) {

this.pageCount = pageCount;

}

public boolean isHasNextPage() {

return hasNextPage;

}

public void setHasNextPage(boolean hasNextPage) {

this.hasNextPage = hasNextPage;

}

public void setHasPrePage(boolean hasPrePage) {

this.hasPrePage = hasPrePage;

}

public int getCurPage() {

return curPage;

}

public void setCurPage(int curPage) {

this.curPage = curPage;

}

public static Page newInstance(String curPage, String pageSize) {

Page page = null;

if (curPage == null || curPage.equals("")) {

page = new Page(1);

} else {

page = new Page(Integer.parseInt(curPage));

page.setPageSize(Integer.parseInt(pageSize));

}

return page;

}

/**

* set the totalCount of page, then calculate

* @param page

* @param hphm

*/

public static void setTolCount(Connection conn, Page page, String sql) {

Statement st = null;

ResultSet rs = null;

try {

st = conn.createStatement();

rs = st.executeQuery(new StringBuffer()

.append(GlobalConst.STR_COUNT)

.append(sql).append(")").toString());

if (rs.next()) {

page.setTolCount(rs.getInt(1));

page.cal();

}

} catch (SQLException e) {

e.printStackTrace();

} finally {

if (rs != null) try {rs.close();} catch (SQLException e) {}

if (st != null) try {st.close();} catch (SQLException e) {}

}

}

public static int getTolCount(Connection conn, String sql) {

Statement st = null;

ResultSet rs = null;

try {

st = conn.createStatement();

rs = st.executeQuery(new StringBuffer()

.append(GlobalConst.STR_COUNT)

.append(sql).append(")").toString());

if (rs.next()) {

return rs.getInt(1);

}

} catch (SQLException e) {

e.printStackTrace();

return -1;

} finally {

if (rs != null) try {rs.close();} catch (SQLException e) {}

if (st != null) try {st.close();} catch (SQLException e) {}

}

return 0;

}

/*

public static void main(String args[]){

Page page = new Page(0);

page.setTolCount(101);

page.cal();

System.out.println("有" + page.getPageCount() + "页");

System.out.println("StartRow(): " + page.getStartRow());

System.out.println("EndRow(): " + page.getEndRow());

System.out.println("有下一页: " + page.isHasNextPage());

System.out.println("有上一页: " + page.isHasPrePage());

}

*/

}

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

//GlobalConst.java

package common;

/**

* 定义一些通用常量

* @author Sugar.Tan

*

*/

public interface GlobalConst {

public static final String STR_COUNT = "SELECT COUNT(*) FROM (";

//for page

public static final String STR_PAGE_START = "SELECT * FROM (SELECT SUB_TAB.*, ROWNUM RN FROM (";

/**

* param1: EndRow number, param2: startRow number.

*/

public static final String STR_PAGE_END = ") SUB_TAB WHERE ROWNUM <= ?) WHERE RN >= ?";

}

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

//DataSource.java

package common;

import java.io.InputStream;

import java.sql.Connection;

import java.sql.DriverManager;

import java.util.Properties;

import common.DataSource;

public class DataSource

{

public Connection getconnection() {

Connection conn = null;

try {

InputStream in = DataSource.class.getResourceAsStream("/jdbc.properties");

Properties pro = new Properties();

pro.load(in);

String classname = pro.getProperty("classname");

String url = pro.getProperty("url");

String userid = pro.getProperty("userid");

String password = pro.getProperty("password");

Class.forName(classname);

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

} catch(Exception e) {

e.printStackTrace();

}

return conn;

}

}

//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

#jdbc.properties, 放在src类路径下

classname=oracle.jdbc.driver.OracleDriver

url=jdbc:oracle:thin:@192.168.1.125:1521:MYORCL

userid=USERONE

password=123456

////////////////////////////////////////////// 测试类 /////////////////////////////////////////////////////////////////////////////////////

//PageTest .java

package common;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import config.DataSource;

public class PageTest {

public static void main(String[] args) {

StringBuffer sbSql = new StringBuffer();

//在这里拼SQL

sbSql.append("SELECT * FROM ITS_TABLE1 W");

sbSql.append(" ORDER BY W.C1 DESC ");

//获取数据库链接

Connection conn = new DataSource().getconnection();

String curPage = "1";

String pageSize = "10";

Page page = Page.newInstance(curPage, pageSize);

common.Page.setTolCount(conn, page, sbSql.toString());

// do the lst result

if (page.getTolCount() > 0) {

PreparedStatement ps = null;

ResultSet rs = null;

try {

ps = conn.prepareStatement(new StringBuffer().append(GlobalConst.STR_PAGE_START)

.append(sbSql)

.append(GlobalConst.STR_PAGE_END).toString());

ps.setInt(1, page.getEndRow());

ps.setInt(2, page.getStartRow());

rs = ps.executeQuery();

while (rs.next()) {

System.out.println("读一条记录");

// ItsObject itsWf = new ItsWf();

// itsWf.setHphm(rs.getString(1));

// //.........

// itsWf.setClbj(rs.getString(12));

// lstItsWf.add(itsWf);

}

} catch (SQLException e) {

e.printStackTrace();

} finally {

if (rs != null) try {rs.close();} catch (SQLException e) {}

if (ps != null) try {ps.close();} catch (SQLException e) {}

if (conn != null) try {conn.close();} catch(SQLException e) {}

}

}

}

}