Java：将文件名分割为基础和扩展名 [英] Java: splitting the filename into a base and extension

问题描述

有更好的方法来获取文件的基本名称和扩展名，比如

Is there a better way to get file basename and extension than something like

File f = ...
String name = f.getName();
int dot = name.lastIndexOf('.');
String base = (dot == -1) ? name : name.substring(0, dot);
String extension = (dot == -1) ? "" : name.substring(dot+1);

推荐答案

我知道其他人提到 String.split ，但这里是一个变体，只能产生两个标记（基数和扩展名）：

I know others have mentioned String.split, but here is a variant that only yields two tokens (the base and the extension):

String[] tokens = fileName.split("\\.(?=[^\\.]+$)");

例如：

"test.cool.awesome.txt".split("\\.(?=[^\\.]+$)");

收益率：

["test.cool.awesome", "txt"]

正则表达式告诉Java在随后任何数量的非周期的任何时间段分割，后跟输入结束。只有一个时期符合这个定义（即最后一个期）。

The regular expression tells Java to split on any period that is followed by any number of non-periods, followed by the end of input. There is only one period that matches this definition (namely, the last period).

技术上从根本上说，这种技术称为零宽正面的前瞻。

Technically Regexically speaking, this technique is called zero-width positive lookahead.

BTW，如果要拆分路径获取完整的文件名，包括但不限于点扩展名，使用带有斜杠的路径，

BTW, if you want to split a path and get the full filename including but not limited to the dot extension, using a path with forward slashes,

    String[] tokens = dir.split(".+?/(?=[^/]+$)");

例如：

    String dir = "/foo/bar/bam/boozled"; 
    String[] tokens = dir.split(".+?/(?=[^/]+$)");
    // [ "/foo/bar/bam/" "boozled" ] 

这篇关于Java：将文件名分割为基础和扩展名的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！