如何在 Java 中解析 CSS 文件，根據選擇器提取特定規則並檢索其樣式？

Java 中的 CSS 解析

在尋找 Java 的 CSS 解析器時，您可以考慮 W3C SAC 介面及其實作。然而，找到這些教程和範例可能具有挑戰性。

推薦和程式碼範例

我強烈建議使用 CSSParser，它以其出色的錯誤回饋而聞名。以下是基於 CSSParser 的修改範例程式碼：

<code class="java">import com.steadystate.css.parser.CSSOMParser;
import org.w3c.css.sac.InputSource;
import org.w3c.dom.css.CSSStyleSheet;
import org.w3c.dom.css.CSSRuleList;
import org.w3c.dom.css.CSSRule;
import org.w3c.dom.css.CSSStyleRule;
import org.w3c.dom.css.CSSStyleDeclaration;
import java.io.*;


public class CSSParserTest {

    protected static CSSParserTest oParser;

    public static void main(String[] args) {
        oParser = new CSSParserTest();
        if (oParser.Parse("design.css")) {
            System.out.println("Parsing completed OK");
        } else {
            System.out.println("Unable to parse CSS");
        }
    }

    public boolean Parse(String cssfile) {
        FileOutputStream out = null;
        PrintStream ps = null;
        boolean rtn = false;

        try {
            // Access CSS file as a resource (must be in package)
            InputStream stream = oParser.getClass().getResourceAsStream(cssfile);
            // Overwrite existing file contents
            out = new FileOutputStream("log.txt");

            if (out != null) {
                // Log file
                ps = new PrintStream(out);
                System.setErr(ps);
            } else {
                return rtn;
            }

            InputSource source = new InputSource(new InputStreamReader(stream));
            CSSOMParser parser = new CSSOMParser();
            CSSStyleSheet stylesheet = parser.parseStyleSheet(source, null, null);

            // Iterate through DOM and inspect
            CSSRuleList ruleList = stylesheet.getCssRules();
            ps.println("Number of rules: " + ruleList.getLength());

            for (int i = 0; i < ruleList.getLength(); i++) {
                CSSRule rule = ruleList.item(i);
                if (rule instanceof CSSStyleRule) {
                    CSSStyleRule styleRule = (CSSStyleRule) rule;
                    ps.println("Selector:" + i + ": " + styleRule.getSelectorText());
                    CSSStyleDeclaration styleDeclaration = styleRule.getStyle();

                    for (int j = 0; j < styleDeclaration.getLength(); j++) {
                        String property = styleDeclaration.item(j);
                        ps.println("Property: " + property);
                        ps.println("Value: " + styleDeclaration.getPropertyCSSValue(property).getCssText());
                        ps.println("Priority: " + styleDeclaration.getPropertyPriority(property));
                    }
                }
            }
        } catch (IOException ioe) {
            System.err.println("IO Error: " + ioe);
        } catch (Exception e) {
            System.err.println("Error: " + e);
        } finally {
            if (ps != null) ps.close();
            if (out != null) out.close();
            if (stream != null) stream.close();
        }
        return rtn;
    }
}</code>

此程式碼可讓您解析 CSS 文件，基於選擇器存取特定規則，並從 CSSStyleDeclaration 物件擷取其樣式。

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