docs: private static DSFactory doCreate(Setting setting) {
  		try {
  			return new HikariDSFactory(setting);
  		} catch (NoClassDefFoundError e) {
  			// ignore
  		}
  		try {
  			return new DruidDSFactory(setting);
  		} catch (NoClassDefFoundError e) {
  			// ignore
  		}
  		try {
  			return new TomcatDSFactory(setting);
  		} catch (NoClassDefFoundError e) {
  			//如果未引入包，此处会报org.apache.tomcat.jdbc.pool.PoolConfiguration未找到错误
  			//因为org.apache.tomcat.jdbc.pool.DataSource实现了此接口，会首先检查接口的存在与否
  			// ignore
  		}
  		try {
  			return new DbcpDSFactory(setting);
  		} catch (NoClassDefFoundError e) {
  			// ignore
  		}
  		try {
  			return new C3p0DSFactory(setting);
  		} catch (NoClassDefFoundError e) {
  			// ignore
  		}
  		return new PooledDSFactory(setting);
  	}