我需要帮助得到正则表达式正确

Question

我试图得到一个正则表达式来查找我的模式的多个条目在一行上。注意:我已经使用Regex大约一个小时了…=/

例如:

<a href="G2532" id="1">back</a> <a href="G2564" id="2">next</a>

应该匹配两次:

1) <a href="G2532" id="1">back</a>
2) <a href="G2564" id="2">next</a>

我认为答案在于正确掌握贪婪、不情愿和占有欲，但我似乎无法做到这一点。

我想我很接近，到目前为止我创建的Regex字符串是:

(<a href=").*(" id="1">).*(</a>)

但是Regex匹配器返回1匹配，整个字符串…

我有一个(可编译的)Java正则表达式测试工具在下面的代码。这是我最近(徒劳的)尝试使用该程序，输出应该是相当直观的。

Enter your regex: (<a href=").*(" id="1">).*(</a>)
Enter input string to search: <a href="G2532" id="1">back</a> <a href="G2564" id="2">next</a>
I found the text "<a href="G2532" id="1">back</a> <a href="G2564" id="2">next</a>" starting at index 0 and ending at index 63.
Enter your regex: (<a href=").*(" id="1">).*(</a>)?
Enter input string to search: <a href="G2532" id="1">back</a> <a href="G2564" id="2">next</a>
I found the text "<a href="G2532" id="1">back</a> <a href="G2564" id="2">next</a>" starting at index 0 and ending at index 63.
Enter your regex: (<a href=").*(" id="1">).*(</a>)+
Enter input string to search: <a href="G2532" id="1">back</a> <a href="G2564" id="2">next</a>
I found the text "<a href="G2532" id="1">back</a> <a href="G2564" id="2">next</a>" starting at index 0 and ending at index 63.
Enter your regex: (<a href=").*(" id="1">).*(</a>)?
Enter input string to search: <a href="G2532" id="1">back</a> <a href="G2564" id="2">next</a>
I found the text "<a href="G2532" id="1">back</a> <a href="G2564" id="2">next</a>" starting at index 0 and ending at index 63.
Enter your regex: ((<a href=").*(" id="1">).*(</a>))?
Enter input string to search: <a href="G2532" id="1">back</a> <a href="G2564" id="2">next</a>
I found the text "<a href="G2532" id="1">back</a> <a href="G2564" id="2">next</a>" starting at index 0 and ending at index 63.
I found the text "" starting at index 63 and ending at index 63.
Enter your regex: ((<a href=").*(" id="1">).*(</a>))+?
Enter input string to search: <a href="G2532" id="1">back</a> <a href="G2564" id="2">next</a>
I found the text "<a href="G2532" id="1">back</a> <a href="G2564" id="2">next</a>" starting at index 0 and ending at index 63.
Enter your regex: (((<a href=").*(" id="1">).*(</a>))+?)
Enter input string to search: <a href="G2532" id="1">back</a> <a href="G2564" id="2">next</a>
I found the text "<a href="G2532" id="1">back</a> <a href="G2564" id="2">next</a>" starting at index 0 and ending at index 63.

Java:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.regex.Pattern;
import java.util.regex.Matcher;
public class RegexTestHarness {
    public static void main(String[] args){
        try{
            while (true) {
                System.out.print("nEnter your regex: ");
                BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
                Pattern pattern = Pattern.compile(reader.readLine());
                System.out.print("Enter input string to search: ");
                Matcher matcher = pattern.matcher(reader.readLine());
                boolean found = false;
                while (matcher.find()) {
                    System.out.println("I found the text "" + matcher.group() + "" starting at " +
                       "index " + matcher.start() + " and ending at index " + matcher.end() + ".");
                    found = true;
                }
                if(!found){
                    System.out.println("No match found.");
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
            System.exit(-1);
        }
    }
}

Answer 1

试试这个:

<a href=".*?" id="1">.*?</a>

我通过在.*

后添加?将捕获转换为非贪婪

但是当你有疑问的时候，你可以使用这个技巧:

<a href="[^"]*" id="1">[^<]*</a>

[^"]*表示非双引号的任意数量的字符
[^<]*表示非左角的任意字符

所以你不用担心贪心/非贪心