public static Integer getInteger(String propertyName, String envName, Integer defaultValue) {
		checkEnvName(envName);
		Integer propertyValue = NumberUtil.toIntObject(System.getProperty(propertyName), null);
		if (propertyValue != null) {
			return propertyValue;
		} else {
			propertyValue = NumberUtil.toIntObject(System.getenv(envName), null);
			return propertyValue != null ? propertyValue : defaultValue;
		}
	}
public static Integer getInteger ( String propertyName , String envName , Integer defaultValue ) { checkEnvName ( envName ) ; Integer propertyValue = NumberUtil . toIntObject ( System . getProperty ( propertyName ) , null ) ; if ( propertyValue != null ) { return propertyValue ; } else { propertyValue = NumberUtil . toIntObject ( System . getenv ( envName ) , null ) ; return propertyValue != null ? propertyValue : defaultValue ; } }
合并系统变量(-D)，环境变量 和默认值，以系统变量优先