libxml2用xpath进行查找

xml文档

    <?xml version="1.0" encoding="UTF-8"?>
    <radios>
        <radio>
            <name>Bayern</name>
            <url>http://mp3.webradio.antenne.de:80</url>
            <classification>
                <area>usa</area>
                <style>music</style>
            </classification>
        </radio>
        <radio>
            <name>DEU-Antenne Bayern</name>
            <url>http://mp3.webradio.antenne.de:80</url>
        </radio>
        <radio>
            <name>DEU-Antenne Bayern</name>
            <url>http://test</url>
        </radio>
    </radios>

代码

    static xmlXPathObjectPtr getNodeset(xmlDocPtr doc, const xmlChar *xpath)
    {
        xmlXPathContextPtr context;
        xmlXPathObjectPtr result;
        context = xmlXPathNewContext(doc);  

        if (context == NULL) {
            printf("context is NULL\n");
            return NULL;
        }  

        result = xmlXPathEvalExpression(xpath, context);
        xmlXPathFreeContext(context);
        if (result == NULL) {
            printf("xmlXPathEvalExpression return NULL\n");
            return NULL;
        }  

        if (xmlXPathNodeSetIsEmpty(result->nodesetval)) {
            xmlXPathFreeObject(result);
            printf("nodeset is empty\n");
            return NULL;
        }  

        return result;
    }

playlistDoc 为 xmlDocPtr类型.

    xmlChar *xpath = BAD_CAST("/radios/radio[name='DEU-Antenne Bayern']");   //关键在这行
    xmlXPathObjectPtr app_result = getNodeset(playlistDoc, xpath);
    if (app_result == NULL)
    {
        printf("app_result is NULL\n");
        return;
    }  

    int i = ;
    xmlChar *value;
    if(app_result)
    {
        xmlNodeSetPtr nodeset = app_result->nodesetval;
        xmlNodePtr cur;  

        for (i=; i < nodeset->nodeNr; i++)
        {
            cur = nodeset->nodeTab[i];
            cur = cur->xmlChildrenNode;  

            while (cur != NULL)
            {
                if (!xmlStrcmp(cur->name, (const xmlChar *)"name"))
                    printf("%s\n", ((char*)XML_GET_CONTENT(cur->xmlChildrenNode)));
                else if (!xmlStrcmp(cur->name, (const xmlChar *)"url"))
                    printf("%s\n", ((char*)XML_GET_CONTENT(cur->xmlChildrenNode)));  

                cur = cur->next;
            }
        }  

        xmlXPathFreeObject(app_result);
    }  

输出:

DEU-Antenne Bayern
http://mp3.webradio.antenne.de:80
DEU-Antenne Bayern
http://test

更多xpath的写法可参考

http://www.w3.org/TR/xpath/

http://www.w3school.com.cn/xpath/index.asp