Java模式正则表达式可在标签之间提取

Question

I am trying to design my custom XML Reader for RSS Feeds. Below is my JAVA Code in testing:

Pattern pattern = Pattern.compile("<(item)(.*?)>((.*))</\\1>", Pattern.CASE_INSENSITIVE);

Matcher matcher = pattern.matcher("<item value=\"key\" atr='none'><title val=\"has value\">Good</title><link>www</link></item>"
+ "<item value=\"key\" atr='none'><title val=\"has value\">Bad</title><link>http</link></item>"
+ "<item value=\"key\" atr='none'><title val=\"has value\">Neutral</title><link>ftp</link></item>");

while (matcher.find()) {
for (int i = 0; i < matcher.groupCount(); i++) {
        System.out.println("\n" + i + ":" + matcher.group(i));
}}

Here is the output:

0:<item value="key" atr='none'><title val="has value">Good</title><link>www</link></item><item value="key" atr='none'><title val="has value">Bad</title><link>http</link></item><item value="key" atr='none'><title val="has value">Neutral</title><link>ftp</link></item>

1:item

2: value="key" atr='none'

3:<title val="has value">Good</title><link>www</link></item><item value="key" atr='none'><title val="has value">Bad</title><link>http</link></item><item value="key" atr='none'><title val="has value">Neutral</title><link>ftp</link>

Desired Output:

<title val="has value">Good</title><link>www</link>
<title val="has value">Bad</title><link>http</link>
<title val="has value">Neutral</title><link>ftp</link>

Basically I want loop should run as much time as much the number of item tag is present in Source String. Currently the 3rd group in regex is extracting the String till the last end tag matching 1st group, which should not be the case. 3rd group should contain the string till the matching the respective end tag of 1st group.

EDIT: On the recommendation of @11thdimension, I am adding some more information what I need:

1. XML Structure can contain other tags also in ITEM tag, like date, author, etc. The code should retrieve those tags also with title & link tags.
2. Hierarchy of tags is not fixed. They can be any order: title, link, date or link, title, date or date, link, title etc.

Answer 1

You should use an XML parser as suggested by Lucero.

However if you must use RegEx then you can use following.

<title.*?<\/link>

Working regex101 link https://regex101.com/r/EWG2Io/2

Edit

For the special case where you need everything inside <item></item> use following

<item.*?>(.*?)<\/item>

Working example https://regex101.com/r/Ow1A5F/1

Also here's Java sample

public class TestRegex {
    public static void main(String[] args) {
        String str = "<item value=\"key\" atr='none'><date><date><title val=\"has value\">Good</title><link>www</link></item><item value=\"key\" atr='none'><title val=\"has value\">Bad</title><link>http</link><author></author></item><item value=\"key\" atr='none'><title val=\"has value\">Neutral</title><link>ftp</link></item>";

        Pattern pattern = Pattern.compile("<item.*?>(.*?)<\\/item>");

        Matcher match = pattern.matcher(str);

        while(match.find()) {
            System.out.println(match.group(1));
        }
    }
}

Output

<date><date><title val="has value">Good</title><link>www</link>
<title val="has value">Bad</title><link>http</link><author></author>
<title val="has value">Neutral</title><link>ftp</link>