XmlJavaxFormat.java 文件源码

private void handleMissingField(String fieldName, XMLEventReader parser,
        XMLEvent event, ExtensionRegistry extensionRegistry, 
        UnknownFieldSet.Builder builder) throws XMLStreamException {

    // skip over the unknown fields, since we can't map them by id, then this message must not know about them.
    // We 'could' map them into the UnknownFieldSet, however none of the other formatters support this..
    // but in the future it would probably be useful for the case: Message A (v2) -> Message B (v1) -> Xml -> Message A (v2) 
    // this would require extra meta data in the xml to know the type of the unknown-field.


    if (event.isStartElement()) {
        /**
         * This loop will eat up everything inside "6"
         * So when this method is called, fieldName = 6, and event is set at index="11"
         * <unknown-field index="6">
         *      <unknown-field index="11">566667</unknown-field>
         *      <unknown-field index="15">
         *          <unknown-field index="16">566667</unknown-field>
         *      </unknown-field>
         * </unknown-field>
         */
        int depth = 1; // we start 1 level down, the value of "6"
        while (parser.hasNext()) {
            XMLEvent nextEvent = parser.nextEvent();
            if (nextEvent.isEndElement()) {
                depth--;
                if (depth <= 0 && parser.peek().isEndElement()) {
                    break;
                }
            } else if (nextEvent.isStartElement()) {
                depth++;
            }
        }
    } else if (event.isCharacters()) {
        // done, let it slide.
    }
}