Add a file to a multipart writer.

Add params to a url string.

Base64URLDecode 因为Base64转码后可能包含有+,/,=这些不安全的URL字符串，所以要进行换字符'+' -> '-''/' -> '_''=' -> ''字符串长度不足4倍的位补"=".

Does the params contain a file?.

CreateOrder 生成订单号.

EncodeURLParams 获取sign 加密 order = 1 正序 order =2 倒叙.

Exists 判断文件或目录是否存在.

Find获取一个切片并在其中查找元素。如果找到它，它将返回它的密钥，否则它将返回-1和一个错误的bool。.

GenerateTraceId 获取链路TraceId.

GenValidateCode 生成6位随机验证码.

GetAddressByIP 获取省市区通过ip.

获取用户IP地址.

GetLock acquireTimeout Get the lock timeout period, If no lock is obtained within this period, err will be returned here lockTimeOut Lock timeout to prevent deadlock, lock automatically unlocked by this time.

GetRandomString 获取随机字符串.

GetRandomString6 获取6位随机字符串.

GetRequestIdKey 获取链路ID.

GetString 只能是map和slice.

InSliceString string是否在[]string里面.

Md5 md5.

Merge headers(latter ones have higher priority).

Merge options(latter ones have higher priority).

NewTime creates a new Time.

ReleaseLock var count = 0 // test assist.

RemoteIp 返回远程客户端的 IP，如 192.168.1.1.

SingCheng 获取sign加密对比 order = 1 正序 order =2 倒叙.

Strval interface转string.

TimeFrom creates a new Time that will always be valid.

TimeFromPtr creates a new Time that will be null if t is nil.

链路ID.

默认时间.

外部链路ID.

Time is a nullable time.Time.