cos 支持创建同名的文件和目录，使用 fileSystem.isDirectory 返回的是文件不合理，无法判断目录是文件合适目录，而 hadoop 是不支持在同一个目录创建同名的文件和目录。

[e-mhui]

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通过文件后缀判断不太合理呀。

Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

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