c3p0连接池

DBManagement

DBManagement/** * * @main This class manager DB connect for a application. * * @author yb * @version 1.0 * @date 2010.4.1 */

import java.sql.Connection;

import java.sql.SQLException;



import com.mchange.v2.c3p0.ComboPooledDataSource;

import com.mchange.v2.c3p0.DataSources;



public class DBManagement {



	private static ComboPooledDataSource cpds = null;



	static {

		try {

			DBManagement.getDataSource();

		} catch (SQLException e) {



			e.printStackTrace();

		}

	}



	public static void getDataSource() throws SQLException {

		cpds = new ComboPooledDataSource();

	}



	public static void destroyDataSource() throws SQLException {

		// 判断连接池是否存在

		if (cpds != null) {

			// 调用C3P0接口，关闭数据库连接池

			DataSources.destroy(cpds);

		}



	}



	public static Connection getConnection() throws SQLException {

		// 判断连接是否已经创建

		if (cpds == null) {



			// 如果没有创建，则新创建一个

			getDataSource();

		}

		// 从连接池中取出一个数据库连接

		return cpds.getConnection();

	}



	/** * @param args */

	public static void main(String[] args) {

		// TODO Auto-generated method stub



	}



}

DBblogic

DBblogicimport java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;



public class DBblogic {



	/** * * @param table * @param con * 完整的条件 */

	public void selectTable(String table, String con) {



		try {

			Connection conc = DBManagement.getConnection();

			String sql = "";

			if (con == null) {

				sql = "SELECT * FROM " + table;

			} else {

				sql = "SELECT * FROM " + table + " where " + con;

			}

			PreparedStatement pstmt = conc.prepareStatement(sql);

			ResultSet rs = pstmt.executeQuery();

			while (rs.next()) {

				System.out.println(rs.getString(1) + rs.getString(2));

			}



		} catch (SQLException e) {

			e.printStackTrace();



		} finally {

			try {

				DBManagement.destroyDataSource();

			} catch (SQLException e) {

				e.printStackTrace();

				System.out.println("数据库重载释放错误 err02");

			}

		}

	}



	/** * @param args */

	public static void main(String[] args) {

		DBblogic dd = new DBblogic();

		dd.selectTable("user", null);



	}



}