Java 从 HTML 标签获取属性的正则表达式
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Regular expression to get an attribute from HTML tag
提问by Krishna Kumar
I am looking for a regular expression that can get me src (case insensitive) tag from following HTML snippets in java.
我正在寻找一个正则表达式，它可以从 Java 中的以下 HTML 片段中获取 src（不区分大小写）标签。
<html><img src="kk.gif" alt="text"/></html>
<html><img src='kk.gif' alt="text"/></html>
<html><img src = "kk.gif" alt="text"/></html>
采纳答案by DMI
One possibility:
一种可能：
String imgRegex = "<img[^>]+src\s*=\s*['\"]([^'\"]+)['\"][^>]*>";
is a possibility (if matched case-insensitively). It's a bit of a mess, and deliberately ignores the case where quotes aren't used. To represent it without worrying about string escapes:
是一种可能性（如果不区分大小写匹配）。有点乱，故意忽略不使用引号的情况。要在不担心字符串转义的情况下表示它：
<img[^>]+src\s*=\s*['"]([^'"]+)['"][^>]*>
This matches:
这匹配：
<img- one or more characters that aren't
>(i.e. possible other attributes) src- optional whitespace
=- optional whitespace
- starting delimiter of
'or" - image source(which may not include a single or double quote)
- ending delimiter
- although the expression can stop here, I then added:
- zero or more characters that are not
>(more possible attributes) >to close the tag
- zero or more characters that are not
<img- 一个或多个不是的字符
>（即可能的其他属性） src- 可选空格
=- 可选空格
'或的起始分隔符"- 图片来源（可能不包括单引号或双引号）
- 结束分隔符
- 虽然表达式可以停在这里，但我接着补充说：
- 零个或多个不是的字符
>（更多可能的属性） >关闭标签
- 零个或多个不是的字符
Things to note:
注意事项：
- If you want to include the
src=as well, move the open bracket further left :-) - This does not care about delimiter balancing or attribute values without delimiters, and it can also choke on badly-formed attributes (such as attributes that include
>or image sources that include'or"). - Parsing HTML with regular expressions like this is non-trivial, and at best a quick hack that works in the majority of cases.
- 如果您还想包含
src=，请将左括号移到更远的地方:-) - 这并不关心平衡定界符或无定界符属性值，并且它也可以呛严重形成的属性（例如包括属性
>包括或图像源'或"）。 - 使用像这样的正则表达式解析 HTML 并非易事，充其量是在大多数情况下都有效的快速技巧。
回答by cletus
This question comes up a lot here.
这个问题在这里经常出现。
Regular expressions are a badway of handling this problem. Do yourself a favour and use an HTML parser of some kind.
正则表达式是处理这个问题的糟糕方法。帮自己一个忙，使用某种 HTML 解析器。
Regexes are flaky for parsing HTML. You'll end up with a complicated expression that'll behave unexpectedly in some corner cases that willhappen otherwise.
正则表达式在解析 HTML 时很不稳定。您最终会得到一个复杂的表达式，该表达式会在某些极端情况下表现出乎意料，否则会发生。
Edit:Ifyour HTML is that simple then:
编辑：如果您的 HTML 如此简单，那么：
Pattern p = Pattern.compile("src\s*=\s*([\"'])?([^ \"']*)");
Matcher m = p.matcher(str);
if (m.find()) {
String src = m.group(2);
}
And there are any number of Java HTML parsersout there.
回答by Mnementh
You mean the src-attribute of the img-Tag? In that case you can go with the following:
你是说 img-Tag 的 src-attribute 吗？在这种情况下，您可以使用以下方法：
<[Ii][Mm][Gg]\s*([Ss][Rr][Cc]\s*=\s*[\"'].*?[\"'])
That should work. The expression src='...' is in parantheses, so it is a matcher-group and can be processed separately.
那应该工作。表达式 src='...' 在括号中，因此它是一个匹配器组，可以单独处理。
回答by Shree Krishna
This answer is for google searchers, Because it's too late
这个答案是针对谷歌搜索者的，因为为时已晚
Copying cletus's showed error and
Modifying his answer and passing modified String src\\s*=\\s*([\"'])?([^\"']*)as parameter passed into Pattern.compileworked for me,
复制 cletus 的显示错误并修改他的答案并将修改后的字符串src\\s*=\\s*([\"'])?([^\"']*)作为参数传递Pattern.compile给我工作，
Here is the full example
这是完整的例子
String htmlString = "<div class=\"current\"><img src=\"img/HomePageImages/Paris.jpg\"></div>"; //Sample HTML
String ptr= "src\s*=\s*([\"'])?([^\"']*)";
Pattern p = Pattern.compile(ptr);
Matcher m = p.matcher(htmlString);
if (m.find()) {
String src = m.group(2); //Result
}
