package?dao;

import?java.sql.Connection;
import?java.sql.PreparedStatement;
import?java.sql.ResultSet;
import?java.sql.SQLException;

import?db.DBConnection;

/**
?*?
?*?取出數(shù)據(jù)，存到二維數(shù)組里
?*?
?*?@return?flowers
?*?@author?lsy
?*/
public?class?SelectData?{
	public?static?final?String?SELECT?=?“select*?from?iris_PCA“;
	public?static?final?int?k?=?4;//?4個(gè)屬性

	public?double[][]?getFlowers（）?throws?SQLException?{
		Connection?con?=?DBConnection.dBConnection（）;
		ResultSet?rs;//?創(chuàng)建結(jié)果集
		PreparedStatement?pstmt?=?con.prepareStatement（SELECT）;//?創(chuàng)建一個(gè)PreparedStatement對(duì)象
		rs?=?pstmt.executeQuery（）;

		//?為初始化數(shù)組的大小提供方便
		int?sample?=?0;
		while?（rs.next（））?{
			sample++;
		}

		double[][]?flower?=?new?double[sample][k];
		rs?=?pstmt.executeQuery（）;//?特別重要，否則取到的全是0。因?yàn)閳?zhí)行上面的while（rs.next（））后，ResultSet對(duì)象的下標(biāo)已指到0。
		//?API：當(dāng)生成ResultSet對(duì)象的Statement對(duì)象關(guān)閉、重新執(zhí)行或用來從多個(gè)結(jié)果的序列獲取下一個(gè)結(jié)果時(shí)，ResultSet對(duì)象將自動(dòng)關(guān)閉。
		for?（int?i?=?0;?rs.next（）;?i++）?{
			for?（int?j?=?0;?j?				flower[i][j]?=?rs.getDouble（j?+?2）;
			}
		}

		pstmt.close（）;
		rs.close（）;
		con.close（）;
		return?flower;
	}
}

?屬性????????????大小?????日期????時(shí)間???名稱
-----------?---------??----------?-----??----
?????目錄???????????0??2015-05-12?15:54??PCA\
?????文件?????????459??2015-05-09?08:35??PCA\.classpath
?????文件?????????379??2015-05-07?08:54??PCA\.project
?????目錄???????????0??2015-05-12?15:54??PCA\.settings\
?????文件?????????629??2015-05-07?08:54??PCA\.settings\org.eclipse.jdt.core.prefs
?????目錄???????????0??2015-05-12?15:54??PCA\bin\
?????目錄???????????0??2015-05-12?15:54??PCA\bin\dao\
?????文件????????1327??2015-05-10?09:27??PCA\bin\dao\SelectData.class
?????目錄???????????0??2015-05-12?15:54??PCA\bin\db\
?????文件????????1363??2015-05-09?22:29??PCA\bin\db\DBConnection.class
?????目錄???????????0??2015-05-12?15:54??PCA\bin\test\
?????文件?????????942??2015-05-12?15:07??PCA\bin\test\Jama_Matrix.class
?????文件?????????773??2015-05-09?08:35??PCA\bin\test\Person.class
?????文件????????2854??2015-05-09?08:35??PCA\bin\test\Sort.class
?????文件????????1528??2015-05-09?08:35??PCA\bin\test\matrixMultiply.class
?????目錄???????????0??2015-05-12?15:54??PCA\bin\util\
?????文件????????5132??2015-05-12?15:49??PCA\bin\util\PCA.class
?????文件????????2872??2015-05-12?15:41??PCA\bin\util\PCAMain.class
?????目錄???????????0??2015-05-12?15:54??PCA\src\
?????目錄???????????0??2015-05-12?15:54??PCA\src\dao\
?????文件????????1232??2015-05-10?09:27??PCA\src\dao\SelectData.java
?????目錄???????????0??2015-05-12?15:54??PCA\src\db\
?????文件?????????976??2015-05-09?22:29??PCA\src\db\DBConnection.java
?????目錄???????????0??2015-05-12?15:54??PCA\src\util\
?????文件????????5366??2015-05-12?15:49??PCA\src\util\PCA.java
?????文件????????2701??2015-05-12?15:41??PCA\src\util\PCAMain.java