GroupFileContainerFileExists 方法

判断当前的文件名是否在文件的列表里，传入文件实际的名称，例如 123.txt，如果文件存在，返回 true, 如果不存在，返回 false
Determine whether the current file name is in the file list, and pass in the actual file name, such as 123.txt, if it exists, return true, if it does not exist, return false

public bool FileExists(
	string fileName
)

Public Function FileExists ( 
	fileName As String
) As Boolean

public:
bool FileExists(
	String^ fileName
)

member FileExists : 
        fileName : string -> bool