英文:
Java Regex to match Dockerfile arg values
问题
我正在尝试提取Dockerfile ARG值，这些值通常有以下形式：
$foo，预期输出：foo
${foo}，预期输出：foo
我想捕获$后面的字符串。我目前正在尝试以下正则表达式，但似乎对于带有花括号的第二个测试用例不起作用：
private static String extract(String input) {
Pattern argPattern = Pattern.compile("^\$([^{}]+)$");
Matcher matcher = argPattern.matcher(input);
if (matcher.find()) {
return (matcher.group(1));
}
return null;
}
请问有谁可以告诉我在这里漏掉了什么？
英文:
I'm trying to extract Dockerfile ARG values which are usually of these forms:
$foo, expected output: foo
${foo}, expected output: foo
I want to capture the string after $. I'm trying this regex right now but it doesn't seem to working for second test case with curly braces:
private static String extract(String input) {
Pattern argPattern = Pattern.compile("^\\$([^{}]+)$");
Matcher matcher = argPattern.matcher(input);
if (matcher.find()) {
return (matcher.group(1));
}
return null;
}
Could anyone please tell me what I'm missing here?
答案1
得分: 1
你可以使用以下正则表达式：
$(?:\{([^{}]+)\}|(\w+))
详情：
\$- 匹配$字符(?:\{([^{}]+)\}|(\w+))- 两个可能的选择之一：\{([^{}]+)\}- 匹配{，然后捕获组 1 匹配除了{和}之外的一个或多个字符，最后匹配}|- 或者(\w+)- 捕获组 2：匹配一个或多个字母、数字或下划线字符
在 Java 演示 中的应用：
String s = "$foo1 expected output: foo ${foo2}, expected output: foo2";
Pattern pattern = Pattern.compile("\$(?:\\{([^{}]+)\\}|(\\w+))");
Matcher matcher = pattern.matcher(s);
while (matcher.find()){
if (matcher.group(1) != null) {
System.out.println(matcher.group(1));
} else {
System.out.println(matcher.group(2));
}
}
输出：foo1 和 foo2。
英文:
You can use
$(?:\{([^{}]+)\}|(\w+))
See the regex demo. Details:
\$- a$char(?:\{([^{}]+)\}|(\w+))- either of the two alternatives:\{([^{}]+)\}-{, then Group 1 capturing one or more chars other than{and}and then a}|- or(\w+)- Group 2: any one or more letters, digits or underscores.
See a Java demo:
String s = "$foo1 expected output: foo ${foo2}, expected output: foo2";
Pattern pattern = Pattern.compile("\\$(?:\\{([^{}]+)\\}|(\\w+))");
Matcher matcher = pattern.matcher(s);
while (matcher.find()){
if (matcher.group(1) != null) {
System.out.println(matcher.group(1));
} else {
System.out.println(matcher.group(2));
}
}
Output: foo1 and foo2.
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