c3p0连接池

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

import 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);

	}

}