fileLogger.go
func NewDefaultLogger(fileDir, fileName string) *FileLogger {
	return NewSizeLogger(fileDir, fileName, "",
		DEFAULT_FILE_COUNT, DEFAULT_FILE_SIZE, DEFAULT_FILE_UNIT, DEFAULT_LOG_SCAN, DEFAULT_LOG_SEQ)
}
func NewDefaultLogger(fileDir, fileName string) *FileLogger {
	return NewSizeLogger(fileDir, fileName, "",
		DEFAULT_FILE_COUNT, DEFAULT_FILE_SIZE, DEFAULT_FILE_UNIT, DEFAULT_LOG_SCAN, DEFAULT_LOG_SEQ)
}
// NewDefaultLogger return a logger split by fileSize by default