/**
     * Parse session id in URL.
     */
    protected void parseSessionId(org.apache.coyote.Request req, Request request) {

        ByteChunk uriBC = req.requestURI().getByteChunk();
        int semicolon = uriBC.indexOf(match, 0, match.length(), 0);

        if (semicolon > 0) {

            // Parse session ID, and extract it from the decoded request URI
            int start = uriBC.getStart();
            int end = uriBC.getEnd();

            int sessionIdStart = semicolon + match.length();
            int semicolon2 = uriBC.indexOf(';', sessionIdStart);//看这行,就知道为什么是;了
            if (semicolon2 >= 0) {
                request.setRequestedSessionId
                    (new String(uriBC.getBuffer(), start + sessionIdStart, 
                            semicolon2 - sessionIdStart));
                // Extract session ID from request URI
                byte[] buf = uriBC.getBuffer();
                for (int i = 0; i < end - start - semicolon2; i++) {
                    buf[start + semicolon + i] 
                        = buf[start + i + semicolon2];
                }
                uriBC.setBytes(buf, start, end - start - semicolon2 + semicolon);
            } else {
                request.setRequestedSessionId
                    (new String(uriBC.getBuffer(), start + sessionIdStart, 
                            (end - start) - sessionIdStart));
                uriBC.setEnd(start + semicolon);
            }
            request.setRequestedSessionURL(true);

        } else {
            request.setRequestedSessionId(null);
            request.setRequestedSessionURL(false);
        }

    }