iOS: libxml2 xpath 函数调用示例, 网页解析

在XPath中使用Contains函数

#import <Foundation/Foundation.h>

#import <libxml/HTMLparser.h>
#import <libxml/HTMLtree.h>
#import <libxml/xpath.h>
#import <libxml/xpathInternals.h>

//读取URL地址的内容
NSString * ReadURLContent(NSString *sURL, NSStringEncoding enc)
{
NSURL *url = [NSURL URLWithString:sURL];
NSString *sResponse = [NSString stringWithContentsOfURL:url encoding:enc error:nil];
return sResponse;
}

//测试解析Baidu的网页
void TestParseBaidu()
{
xmlDocPtr doc = NULL;
xmlNodePtr node = NULL;

//读取网页内容
NSString *sURL = @"http://www.baidu.com";
NSStringEncoding enc = NSUTF8StringEncoding;
NSString *sContent = ReadURLContent(sURL, enc);

//解析网页
doc = htmlReadDoc((xmlChar *)[sContent cStringUsingEncoding:enc], NULL, NULL, HTML_PARSE_NOWARNING | HTML_PARSE_NOERROR);
if (doc == NULL) {
printf("无法解析网页%s\n", [sURL cStringUsingEncoding: NSUTF8StringEncoding]);
return;
}

//得到根节点
node = xmlDocGetRootElement(doc);
printf("根节点名称: %s\n", node->name);

//使用xPath函数查找Script节点
xmlXPathContextPtr context = NULL;
xmlXPathObjectPtr result = NULL;
const xmlChar *sScriptTag = (const xmlChar *)"src";
const xmlChar *sXpath = (const xmlChar *)"//script [contains(@src,'.js')]";
context = xmlXPathNewContext(doc);
result = xmlXPathEvalExpression(sXpath, context);
if(xmlXPathNodeSetIsEmpty(result->nodesetval)){
printf("没有选择结果\n");
}

//输出链接js脚本
for(int i=0; i<result->nodesetval->nodeNr; i++){
node = result->nodesetval->nodeTab[i];
xmlChar *sScriptFile = xmlGetProp(node, sScriptTag);
printf("%s: %s\n", node->name, sScriptFile);
xmlFree(sScriptFile);
}

//释放内存
xmlXPathFreeObject(result);
xmlXPathFreeContext(context);
xmlFreeDoc(doc);
xmlCleanupParser();
}

int main(int argc, const char * argv[])
{
@autoreleasepool {
TestParseBaidu();
}
return 0;
}