pagehelper.java

企业进销存源码

package com.web.util;

import java.sql.*;
import java.util.*;

import com.common.*;
import com.common.util.Item;
import com.common.util.ReadHelper;
import com.dao.util.DbConnect;




public abstract class PageHelper {

	//get pageNum data.
	public Page getPage(String pageNum, int pageSize) {

		long numberPerPage = pageSize;
		int pNum = 1;
		int currPageNum = 1;

		Connection conn = null;
		Statement stm = null;
		ResultSet rs = null;

		long rCount = 0;

		ArrayList list = new ArrayList();

		String sqlstr = getSqlStr();

		if (pageNum == null)
			pageNum = "1";

		try {
			pNum = (Integer.parseInt(pageNum) - 1) * (int) numberPerPage + 1;
			currPageNum = Integer.parseInt(pageNum);

		} catch (Exception ex) {
			ex.printStackTrace();
		}

		try {
			DbConnect db = new DbConnect();
			conn=db.getConnection();
			stm =
				conn.createStatement(
					ResultSet.TYPE_SCROLL_INSENSITIVE,
					ResultSet.CONCUR_READ_ONLY);

			rs = stm.executeQuery(sqlstr);

			//whether pNum is great than record count.
			long recordCount = this.getCount(rs);
			//long recordCount = this.getCount(sqlstr);

			if (recordCount < pNum)
				throw new Exception("Not found more data.");

			//rs.setFetchSize((int) numberPerPage);

			int count = 0;
			rs.absolute((int) pNum);

			ResultSetMetaData rsmd = rs.getMetaData();
			int colCount = rsmd.getColumnCount();

			do{

				Item item = new Item();

				//Add a row data into item.
				for (int i = 1; i <= colCount; i++) {
					Object obj = rs.getObject(i);

					if (rs.wasNull())
						obj = "";

					item.addAttribute(rsmd.getColumnName(i), obj);
				}

				//Add the item into arraylist.
				list.add(item);

				count++;

			}while(count < numberPerPage && rs.next());


			rCount = recordCount;

		} catch (Exception ex) {
			//ex.printStackTrace();
		} finally {
			try {
				if (rs != null)
					rs.close();
				if (stm != null)
					stm.close();
				rs = null;
				stm = null;
				conn.close();
			} catch (Exception ex) {
				ex.printStackTrace();
			}
		}

		Page pg = new Page(list, rCount, currPageNum, pageSize);

		return pg;
	}

	protected long getCount(ResultSet rs) {
		long result = 0;

		try {
			int pos = rs.getRow();

			rs.last();

			result = rs.getRow();

			rs.first();

		} catch (Exception ex) {
			ex.printStackTrace();
		}

		return result;
	}

	protected long getCount(String sqlStr) {

		long result = 0;
		ReadHelper rh = new ReadHelper();

		Item item =
			rh.getItem("SELECT COUNT(*) AS total FROM " + getTableName(sqlStr));

		result = item.getLong("total");

		return result;
	}

	public abstract String getSqlStr();

	//public abstract getSqlStr(File settingsFile,String tags);

	private String getTableName(String sqlStr) {
		String tableName = "";

		String tempStr = sqlStr.toUpperCase();
		int firstPos = tempStr.indexOf("FROM");
		
		tableName = tempStr.substring(firstPos + 4);


		return tableName;
	}

	public static void main(String args[]) {

	}
}