private void detectEncoding()

in src/main/java/org/apache/commons/io/output/XmlStreamWriter.java [205:250]
36 lines of code
9 McCabe index (conditional complexity)

    private void detectEncoding(final char[] cbuf, final int off, final int len)
            throws IOException {
        int size = len;
        final StringBuffer xmlProlog = prologWriter.getBuffer();
        if (xmlProlog.length() + len > BUFFER_SIZE) {
            size = BUFFER_SIZE - xmlProlog.length();
        }
        prologWriter.write(cbuf, off, size);

        // try to determine encoding
        if (xmlProlog.length() >= 5) {
            if (xmlProlog.substring(0, 5).equals("<?xml")) {
                // try to extract encoding from XML prolog
                final int xmlPrologEnd = xmlProlog.indexOf("?>");
                if (xmlPrologEnd > 0) {
                    // ok, full XML prolog written: let's extract encoding
                    final Matcher m = XmlStreamReader.ENCODING_PATTERN.matcher(xmlProlog.substring(0,
                            xmlPrologEnd));
                    if (m.find()) {
                        final String encName = m.group(1).toUpperCase(Locale.ROOT);
                        charset = Charset.forName(encName.substring(1, encName.length() - 1));
                    } else {
                        // no encoding found in XML prolog: using default
                        // encoding
                        charset = defaultCharset;
                    }
                } else if (xmlProlog.length() >= BUFFER_SIZE) {
                    // no encoding found in first characters: using default
                    // encoding
                    charset = defaultCharset;
                }
            } else {
                // no XML prolog: using default encoding
                charset = defaultCharset;
            }
            if (charset != null) {
                // encoding has been chosen: let's do it
                prologWriter = null;
                writer = new OutputStreamWriter(out, charset);
                writer.write(xmlProlog.toString());
                if (len > size) {
                    writer.write(cbuf, off + size, len - size);
                }
            }
        }
    }