c3p0数据库连接池问题

public class DBConnectionManager {
	private static  DBConnectionManager instance = null;
	private static Logger log = Logger.getLogger(DBConnectionManager.class);
	ComboPooledDataSource cpds = null;
	private DBConnectionManager() {
		try{
			cpds = new ComboPooledDataSource();
			cpds.setDriverClass( "com.mysql.jdbc.Driver" ); //loads the jdbc driver            
			cpds.setJdbcUrl( "jdbc:mysql://localhost/uso" );
			cpds.setUser("root");                                  
			cpds.setPassword("123456");
		}catch(Exception ex){			
		}
	}
	public static synchronized DBConnectionManager getInstance() {
		if (instance == null){
			instance = new DBConnectionManager();
		}
		return instance;
	}
	public Connection getConnection() throws SQLException{
		log.info("GET CONNECTION");
		try{
			Connection conn = cpds.getConnection();
			log.info(conn);
			return conn;
		}catch(Exception ex){			
			return null;
		}
	}

}
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