用于在两个字符之间查找字符串的正则表达式模式-但第二个字符首次出现

Question

I want a regex to find string between two characters but only from start delimiter to first occurrence of end delimiter

I want to extract story from the lines of following format

<metadata name="user" story="{some_text_here}" \/>

So I want to extract only : {some_text_here}

For that I am using the following regex:

<metadata name="user" story="(.*)" \/>

And java code:

public static void main(String[] args) throws IOException {
        String regexString = "<metadata name="user" story="(.*)" \/>";
        String filePath = "C:\\Desktop\\temp\\test.txt";
        Pattern p = Pattern.compile(regexString);
        Matcher m;
        try (BufferedReader br = new BufferedReader(new FileReader(filePath))) {
            String line;
            while ((line = br.readLine()) != null) {
                m = p.matcher(line);
                if (m.find()) {                     
                    System.out.println(m.group(1));
                }
            }
        }

    }

This regex mostly works fine but surprisingly if the line is:

<metadata name="user" story="My name is Nick" extraStory="something" />

Running the code also filters My name is Nick" extraStory="something where as I only want to make sure that I get My name is Nick

Also I want to make sure that there is actually no information between story="My name is Nick" and before />

Answer 1

<metadata name="user" story="([^"]*)" \/>

[^"]* will match everything except the ". In this case the string

<metadata name="user" story="My name is Nick" extraStory="something" />

will not be matched.

Answer 2

The following XPath should solve your problem :

//metadata[@name='user' and @story and count(@*) = 2]/@story

It address the story attribute of any metadata node in the document whose name attribute is user , which also has a story attribute but no others (attributes count is 2).

(Note : //metadata[@name='user' and count(@*)=2]/@story would be enough since it would be impossible to address the story attribute of a metadata node whose second attribute isn't story )

In Java code, supposing you are handling an instance of org.w3c.dom.Document and already have an instance of XPath available, the code would be the following :

xPath.evaluate("//metadata[@name='user' and @story and count(@*) = 2]/@story", xmlDoc);

You can try the XPath here or the Java code here .

Answer 3

Just use Jsoup . right tool for the problem :).

its this easy :

String html; //read html file

Document document = Jsoup.parse(html);

String story = document.select("metadata[name=user]").attr("story");

System.out.println(story);