讓不同版本的oracle jdbc driver並存於同一個JVM

package manager;

import java.sql.Connection;
import java.sql.DriverManager;
public class OracleDriverManager
{
  public Connection getConnection(String databaseURL, String userName, String password)
  {
    Connection ret = null;
    try {
      Class.forName("oracle.jdbc.driver.OracleDriver");
      ret = DriverManager.getConnection(databaseURL, userName, password);
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
    return ret;
  }
}

當程式需同時連接oracle 8i及oracle 11g而需不同的jdbc driver時，可另外用一個UrlClassLoader將舊的jdbc driver load進來，並將上面的class也load進與舊版jdbc driver同一個ClassLoader，再主程式用reflection的方式來使用OracleDriverManager去取得connection，如此才能讓DriverManager裡註冊的driver一致。

package tester;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

import aic.Oracle8iManager;

public class Oracle8iTester {

    /**
     * @param args
     */
    public static void main(String[] args) {
        new Oracle8iTester().test();

    }

    private void test() {
        String driverClassName = "oracle.jdbc.driver.OracleDriver";
        String orclURL = "jdbc:oracle:thin:@localhost:1521:orcl";//11g
        String ora8iURL = "jdbc:oracle:thin:@ora8ihost:1521:ora8i";//8i
        String userName = "apps";
        String password = "apps";

        try {
            Connection ora8iConn = Oracle8iManager.getInstance().getConnection(ora8iURL, userName, password);
            println(ora8iConn);
            testConnection(ora8iConn);
        } catch (Exception e) {
            e.printStackTrace();
        }

        try {
            Class.forName(driverClassName);
            Connection orclConn = DriverManager.getConnection(orclURL, userName, password);
            println(orclConn);
            testConnection(orclConn);
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    private void testConnection(Connection conn) throws Exception {
        Statement statement = conn.createStatement();
        ResultSet resultSet = statement.executeQuery("SELECT 'success' FROM dual");

        String str = null;
        if (resultSet.next()) {
            str = resultSet.getString(1);
        }
        resultSet.close();
        statement.close();
        conn.close();

        println(str);
    }

    private void println(Object o) {
        System.out.println(o);
    }

}