canonicalpath和absolutepath之间的区别是什么？ [英] what's the difference between canonicalpath and absolutepath?

问题描述

可能重复：

Java中的getPath（），getAbsolutePath（）和getCanonicalPath（）有什么区别？

这两者之间有什么区别？

Any difference between those two?

canonicalpath和absolutepath？

canonicalpath and absolutepath?

如果有差异，将需要一个真实世界的例子。

If having difference, a real world example will be needed.

推荐答案

区别在于文件 ^[1] 只有一条规范路径，而文件的绝对路径可能很多（取决于系统）。例如，在Unix系统上， / usr / local /../ bin 与 / usr / bin 。 getCanonicalPath（）解决这些歧义并返回（唯一的）规范路径。因此，如果当前目录是 / usr / local ，那么：

The difference is that there is only one canonical path to a file^[1], while there can be many absolute paths to a file (depending on the system). For instance, on a Unix system, /usr/local/../bin is the same as /usr/bin. getCanonicalPath() resolves those ambiguities and returns the (unique) canonical path. So if the current directory was /usr/local, then:

File file = new File("../bin");
System.out.println(file.getPath());
System.out.println(file.getAbsolutePath());
System.out.println(file.getCanonicalPath());

将打印：

../ bin

/usr/local/../bin

/ usr / bin

../bin
/usr/local/../bin
/usr/bin

Per Voo的建议：在Unix系统上，如果符号链接存在， getCanonicalPath（）也将解析符号链接。硬链接被视为普通文件（基本上就是它们）。但请注意，这些方法不需要存在文件才能成功。

Per Voo's suggestion: on Unix systems, getCanonicalPath() will also resolve symbolic links if the symbolic link exists. Hard links are treated like normal files (which is basically what they are). Note, however, that a file need not exist for these methods to succeed.

^[1] _{嗯，不完全。正如@Tom Hale在评论中指出的那样，如果文件系统支持硬链接目录，则可能存在指向给定文件的多个规范路径。}

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