文件、文件夹删除
boolean java.io.File.delete()
若是文件，删除。若是文件夹，只有它为非空时才删除。
Deletes the file or directory denoted by this abstract pathname. If this pathname denotes a directory, then the directory must be empty in order to be deleted.
boolean java.io.File.delete()
若是文件，删除。若是文件夹，只有它为非空时才删除。
Deletes the file or directory denoted by this abstract pathname. If this pathname denotes a directory, then the directory must be empty in order to be deleted.
