java 中File.length() 和InputStream.avalible()

最新推荐文章于 2023-11-02 20:59:34 发布

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最新推荐文章于 2023-11-02 20:59:34 发布

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本文介绍了如何使用File.length()获取文件的字节长度，并解释了该方法在文件不存在时的返回值。此外，还讨论了InputStream.available()方法，它可以估算在不阻塞等待更多输入的情况下可以读取或跳过的字节数。需要注意的是，available()方法的返回值不应直接用于容器大小的设置。

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1. File.length()

Returns the length of this file in bytes. Returns 0 if the file does not exist. The result for a directory is not defined.

2. InputStream.avalible()

Returns an estimated number of bytes that can be read or skipped without blocking for more input.

..It is particularly important to realize that you must not use this method to size a container and assume that you can read the entirety of the stream without needing to resize the container.

..if you're reading from a file, length() returns the current length of the file (though assuming the file's length can't change may be incorrect, reading a file is inherently racy).