两个分隔符之间的子串 [英] substring between two delimiters

问题描述

我有一个字符串：这是一个网址 http://www.google.com/MyDoc应该使用的.pdf

I have a string as : "This is a URL http://www.google.com/MyDoc.pdf which should be used"

我只需要提取从http开始并以pdf结尾的URL：
http://www.google.com/MyDoc.pdf

I just need to extract the URL that is starting from http and ending at pdf : http://www.google.com/MyDoc.pdf

String sLeftDelimiter = "http://";
String[] tempURL = sValueFromAddAtt.split(sLeftDelimiter );
String sRequiredURL = sLeftDelimiter + tempURL[1];

这使我的输出为http://www.google.com/MyDoc.pdf应该使用

This gives me the output as "http://www.google.com/MyDoc.pdf which should be used"

需要帮助。

推荐答案

这个问题是正则表达式的用法：

This kind of problem is what regular expressions were made for:

Pattern findUrl = Pattern.compile("\\bhttp.*?\\.pdf\\b");
Matcher matcher = findUrl.matcher("This is a URL http://www.google.com/MyDoc.pdf which should be used");
while (matcher.find()) {
  System.out.println(matcher.group());
}

正则表达式解释：

• \ b 在http之前有一个单词边界（即xhttp不匹配）


• http 字符串http（请注意，这也匹配https和httpsomething）


• 。*？任意数字（。）任意次数（ * ），但尝试使用最少量的字符（？）


• \。 pdf 文字字符串.pdf


• \ b 在.pdf之后单词边界（即.pdfoo不匹配）

• \b before the "http" there is a word boundary (i.e. xhttp does not match)
• http the string "http" (be aware that this also matches "https" and "httpsomething")
• .*? any character (.) any number of times (*), but try to use the least amount of characters (?)
• \.pdf the literal string ".pdf"
• \b after the ".pdf" there is a word boundary (i.e. .pdfoo does not match)

如果您只想匹配http和https，请尝试使用此代替字符串中的 http ：

If you would like to match only http and https, try to use this instead of http in your string:

• https？\\ \\： - 这匹配字符串http，然后是一个可选的s（在s之后由？表示）然后是冒号。

• https?\: - this matches the string http, then an optional "s" (indicated by the ? after the s) and then a colon.

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