import java.io.*;
import java.util.*;
import java.sql.*;
import javax.naming.*;
import javax.sql.*;
public class ConnectionFactory
{

/**

oracle   分页

select * from (
select a.*, ROWNUM rn from ( select * from user_info )  a
where ROWNUM<=40 )
where rn >=21

*/
    private static Properties config = new Properties();
   
    static
    {
        try
        {
            InputStream in = ConnectionFactory.class.getClassLoader().getResourceAsStream("dbconfig.properties");
            config.load(in);
            in.close();
        }catch(IOException e)
        {
            e.printStackTrace();
            throw new ExceptionInInitializerError(e.getMessage());
        }
    }
   
    public static Connection getConnection()
    {
        if(config.getProperty("jndi-name") != null)
        {
            return getJndiConnection();
        }
       
        return getDirectConnection();
    }
   
    public static Connection getJndiConnection()
    {
        Connection con = null;
        try
        {
/**context.xml

数据源的配置
<Context>
      <Resource name="jdbc/oracle" auth="Container" type="javax.sql.DataSource" maxActive="2" maxIdle="1" maxWait="-1"
      username="openlab" password="open123" driverClassName="oracle.jdbc.driver.OracleDriver" url="jdbc:oracle:thin:@192.168.0.20:1521:tarena"/>
</Context 
*/
            Context ctx = new InitialContext();
            DataSource ds = (DataSource)ctx.lookup("java:comp/env/" + config.getProperty("jndi-name"));
            con = ds.getConnection();
        }catch(Exception e)
        {
            e.printStackTrace();
        }
        return con;
    }
   
    public static Connection getDirectConnection()
    {
        Connection con = null;
        try
        {
            Class.forName(config.getProperty("driver"));
            con = DriverManager.getConnection(config.getProperty("dburl") ,config.getProperty("user"), config.getProperty("password"));
        }catch(ClassNotFoundException cne)
        {
            cne.printStackTrace();
        }catch(SQLException sqle)
        {
            sqle.printStackTrace();
        }
       
        return con;
    }
   
    public static void close(ResultSet rs, Statement st, Connection con)
    {
        try
        {
            rs.close();
        }catch(Exception e)
        {
        }
       
        try
        {
            st.close();
        }catch(Exception e)
        {
        }
       
        try
        {
            con.close();
        }catch(Exception e)
        {
        }
    }
   
    public static void main(String[] args) throws Exception
    {
        Connection con = ConnectionFactory.getConnection();
        System.out.println(con);
        con.close();
    }
}