String calculateHttpEncoding()

in src/main/java/org/apache/commons/io/input/XmlStreamReader.java [670:735]
49 lines of code
20 McCabe index (conditional complexity)

    String calculateHttpEncoding(final String httpContentType, final String bomEnc, final String xmlGuessEnc, final String xmlEnc, final boolean lenient)
            throws IOException {

        // Lenient and has XML encoding
        if (lenient && xmlEnc != null) {
            return xmlEnc;
        }

        // Determine mime/encoding content types from HTTP Content Type
        final String cTMime = getContentTypeMime(httpContentType);
        final String cTEnc = getContentTypeEncoding(httpContentType);
        final boolean appXml = isAppXml(cTMime);
        final boolean textXml = isTextXml(cTMime);

        // Mime type NOT "application/xml" or "text/xml"
        if (!appXml && !textXml) {
            final String msg = MessageFormat.format(HTTP_EX_3, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
            throw new XmlStreamReaderException(msg, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
        }

        // No content type encoding
        if (cTEnc == null) {
            if (appXml) {
                return calculateRawEncoding(bomEnc, xmlGuessEnc, xmlEnc);
            }
            return defaultEncoding == null ? US_ASCII : defaultEncoding;
        }

        // UTF-16BE or UTF-16LE content type encoding
        if (cTEnc.equals(UTF_16BE) || cTEnc.equals(UTF_16LE)) {
            if (bomEnc != null) {
                final String msg = MessageFormat.format(HTTP_EX_1, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
                throw new XmlStreamReaderException(msg, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
            }
            return cTEnc;
        }

        // UTF-16 content type encoding
        if (cTEnc.equals(UTF_16)) {
            if (bomEnc != null && bomEnc.startsWith(UTF_16)) {
                return bomEnc;
            }
            final String msg = MessageFormat.format(HTTP_EX_2, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
            throw new XmlStreamReaderException(msg, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
        }

        // UTF-32BE or UTF-132E content type encoding
        if (cTEnc.equals(UTF_32BE) || cTEnc.equals(UTF_32LE)) {
            if (bomEnc != null) {
                final String msg = MessageFormat.format(HTTP_EX_1, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
                throw new XmlStreamReaderException(msg, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
            }
            return cTEnc;
        }

        // UTF-32 content type encoding
        if (cTEnc.equals(UTF_32)) {
            if (bomEnc != null && bomEnc.startsWith(UTF_32)) {
                return bomEnc;
            }
            final String msg = MessageFormat.format(HTTP_EX_2, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
            throw new XmlStreamReaderException(msg, cTMime, cTEnc, bomEnc, xmlGuessEnc, xmlEnc);
        }

        return cTEnc;
    }