正则表达式去除 HTML 标签

Question

我有这个 HTML 输入：

<font size="5"><p>some text</p>
<p> another text</p></font>

我想使用正则表达式来删除 HTML 标签，这样输出是：

some text
another text

谁能建议如何使用正则表达式来做到这一点？

Answer 1

既然你问了，这里有一个快速而肮脏的解决方案：

String stripped = input.replaceAll("<[^>]*>", "");

(Ideone.com demo)

虽然使用正则表达式处理 HTML 是一个非常糟糕的主意。上面的 hack 不会处理像

这样的东西

• <tag attribute=">">Hello</tag>
• <script>if (a < b) alert('Hello>');</script>

等等

更好的方法是使用例如Jsoup。要从字符串中删除所有标签，您可以例如执行Jsoup.parse(html).text()。

Answer 2

使用 HTML 解析器。这是一个Jsoup 示例。

String input = "<font size=\"5\"><p>some text</p>\n<p>another text</p></font>";
String stripped = Jsoup.parse(input).text();
System.out.println(stripped);

结果：

一些文本另一个文本

或者如果你想保留换行符：

String input = "<font size=\"5\"><p>some text</p>\n<p>another text</p></font>";
for (String line : input.split("\n")) {
    String stripped = Jsoup.parse(line).text();
    System.out.println(stripped);
}

结果：

一些文字 另一个文本

Jsoup 也提供了更多优势。您可以使用select() 方法轻松提取 HTML 文档的特定部分，该方法接受类似 jQuery 的 CSS 选择器。它只要求文档在语义上格式正确。自 1998 年以来已弃用的 <font> 标签的存在已经不是一个很好的指示，但如果您事先深入了解 HTML 结构，它仍然是可行的。

另见：

• Pros and cons of leading HTML parsers in Java

Answer 3

您可以使用名为 Jericho Html 解析器的 HTML 解析器。

你可以从这里下载它 - http://jericho.htmlparser.net/docs/index.html

Jericho HTML Parser 是一个 java 库，允许分析和操作 HTML 文档的各个部分，包括服务器端标签，同时逐字复制任何无法识别或无效的 HTML。它还提供高级 HTML 表单操作功能。

存在格式错误的 HTML 不会干扰解析

Answer 4

从aioobe的代码开始，我尝试了更大胆的：

String input = "<font size=\"5\"><p>some text</p>\n<p>another text</p></font>";
String stripped = input.replaceAll("</?(font|p){1}.*?/?>", "");
System.out.println(stripped);

去除每个 HTML 标记的代码如下所示：

public class HtmlSanitizer {

    private static String pattern;

    private final static String [] tagsTab = {"!doctype","a","abbr","acronym","address","applet","area","article","aside","audio","b","base","basefont","bdi","bdo","bgsound","big","blink","blockquote","body","br","button","canvas","caption","center","cite","code","col","colgroup","content","data","datalist","dd","decorator","del","details","dfn","dir","div","dl","dt","element","em","embed","fieldset","figcaption","figure","font","footer","form","frame","frameset","h1","h2","h3","h4","h5","h6","head","header","hgroup","hr","html","i","iframe","img","input","ins","isindex","kbd","keygen","label","legend","li","link","listing","main","map","mark","marquee","menu","menuitem","meta","meter","nav","nobr","noframes","noscript","object","ol","optgroup","option","output","p","param","plaintext","pre","progress","q","rp","rt","ruby","s","samp","script","section","select","shadow","small","source","spacer","span","strike","strong","style","sub","summary","sup","table","tbody","td","template","textarea","tfoot","th","thead","time","title","tr","track","tt","u","ul","var","video","wbr","xmp"};

    static {
        StringBuffer tags = new StringBuffer();
        for (int i=0;i<tagsTab.length;i++) {
            tags.append(tagsTab[i].toLowerCase()).append('|').append(tagsTab[i].toUpperCase());
            if (i<tagsTab.length-1) {
                tags.append('|');
            }
        }
        pattern = "</?("+tags.toString()+"){1}.*?/?>";
    }

    public static String sanitize(String input) {
        return input.replaceAll(pattern, "");
    }

    public final static void main(String[] args) {
        System.out.println(HtmlSanitizer.pattern);

        System.out.println(HtmlSanitizer.sanitize("<font size=\"5\"><p>some text</p><br/> <p>another text</p></font>"));
    }

}

我写这个是为了符合 Java 1.4，出于一些可悲的原因，所以请随意使用 StringBuilder...

优点：

• 您可以生成要去除的标签列表，这意味着您可以保留您想要的标签
• 避免剥离不是 HTML 标记的内容
• 保留空格

缺点：

• 您必须列出所有要从字符串中去除的 HTML 标记。这可能很多，例如，如果您想剥离所有内容。

如果您发现任何其他缺点，我真的很高兴知道它们。

Answer 5

如果你使用Jericho，那么你只需要使用这样的东西：

public String extractAllText(String htmlText){
    Source source = new Source(htmlText);
    return source.getTextExtractor().toString();
}

当然，即使使用Element，您也可以这样做：

for (Element link : links) {
  System.out.println(link.getTextExtractor().toString());
}