libxml2用xpath进行查找

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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>

上代码

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 = 0;    xmlChar *value;    if(app_result)    {        xmlNodeSetPtr nodeset = app_result->nodesetval;        xmlNodePtr cur;        for (i=0; 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

xmlChar *xpath = BAD_CAST("/radios/radio[name='DEU-Antenne Bayern']");

改成

 xmlChar *xpath = BAD_CAST("/radios/radio[name='DEU-Antenne Bayern' and url='http://mp3.webradio.antenne.de:80']");DEU-Antenne Bayern

输出:

http://mp3.webradio.antenne.de:80

更多xpath的写法可参考

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

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

作者:帅得不敢出门 c++哈哈堂:31843264