html - 如何解析 HTML 以搜索特定内容的针

Question

鉴于下面的 NSString 最初是从使用 NSXMLParser 解析 XML 文档检索到的 CData 对象转换而来的，我如何才能获得图书的以下属性:标题、图书图片封面、作者、价格和评级？

这是我获得以下属性的基本解决方案

1. Book Title - 我可能可以通过查看 riRssTitle span 类来获得它，但是我必须弄清楚如何在两者之间阅读标题ahref url 标签获取标题

2. Book Image - 我必须通过获取第一个 URL http://ecx.images-amazon.com/images/I/41Lg22K3ViL._SL160_PIsitb-sticker -arrow-dp,TopRight,12,-18_SH30_OU02_.jpg 然后将所有内容留给 http://ecx.images-amazon.com/images/I/41Lg22K3ViL 省略其余部分，然后附加 .jpg 标签以获得完整的 url，以便稍后检索图像。

3. Book Author - 我必须执行与第 1 步相同的步骤，但要搜索 riRssContributor span 标签。

   <

4. 书价 - 这里没有所有商品通用的价格标签，但我看到的一个共同点是价格始终在字体标签 然后它位于 BOLD 标记 中。

5. Rating - 可以通过查找包含单词 stars 的 URL 来检索，然后获取后面的数字，4 表示 4 星，任何附加有 -5 的数字表示额外的 .5 星。所以 3-5 表示 3.5 颗星。

在不弄乱的情况下最好的方法是什么？此外，我不喜欢如果亚马逊决定更改其显示其 URL 的方式，我的代码将如何中断，我的应用程序依赖于亚马逊维护其 url 命名约定。

但就目前而言，这是最好的前进方式吗？有没有一个快速解析器可以实现我想做的事情？

这是亚马逊 RSS 提要的示例:http://www.amazon.co.uk/gp/rss/bestsellers/books/72/ref=zg_bs_72_rsslink

---

下面是我为每个项目检索的 CData NSString 数据。

<div style="float:left;">
    <a class="url" href="http://www.amazon.co.uk/Gone-Girl-Gillian-Flynn/dp/0753827662/ref=pd_zg_rss_ts_b_72_9">
        <img src="http://ecx.images-amazon.com/images/I/41Lg22K3ViL._SL160_PIsitb-sticker-arrow-dp,TopRight,12,-18_SH30_OU02_.jpg" alt="Gone Girl" border="0" hspace="0" vspace="0" />
    </a>
</div>
<span class="riRssTitle">
    <a href="http://www.amazon.co.uk/Gone-Girl-Gillian-Flynn/dp/0753827662/ref=pd_zg_rss_ts_b_72_9">Gone Girl</a>
</span>
<br />
<span class="riRssContributor">
    <a href="http://www.amazon.co.uk/Gillian-Flynn/e/B001JP3W46/ref=ntt_athr_dp_pel_1">Gillian Flynn</a>
    <span class="byLinePipe">(Author)</span>
</span>
<br />
<img src="http://g-ecx.images-amazon.com/images/G/02/x-locale/common/icons/uparrow_green_trans._V192561975_.gif" width="13" align="abstop" alt="Ranking has gone up in the past 24 hours" title="Ranking has gone up in the past 24 hours" height="11" border="0" />
<font color="green">
    <strong></strong>
</font> 674 days in the top 100 
<br />
<img src="http://g-ecx.images-amazon.com/images/G/02/detail/stars-4-0._V192253865_.gif" width="64" height="12" border="0" style="margin: 0; padding: 0;"/>(5704)
<br />
<br />
<a href="http://www.amazon.co.uk/Gone-Girl-Gillian-Flynn/dp/0753827662/ref=pd_zg_rss_ts_b_72_9">Buy new: </a>
<strike>£9.07</strike>
<font color="#990000">
    <b>£3.85</b>
</font>
<br />
<a href="http://www.amazon.co.uk/gp/offer-listing/0753827662/ref=pd_zg_rss_ts_b_72_9?ie=UTF8&condition=all">60 used & new</a> from 
<span class="price">£2.21</span>
<br />
<br />(Visit the 
<a href="http://www.amazon.co.uk/Best-Sellers-Books-Crime-Thrillers-Mystery/zgbs/books/72/ref=pd_zg_rss_ts_b_72_9">Bestsellers in Crime, Thrillers & Mystery</a> list for authoritative information on this product's current rank.)

Answer 1

TFHpple 绝对是用来解析 HTML 的库。 (github 上超过 1000 颗星) https://github.com/topfunky/hpple

这是该 RSS 提要的 obj-c 解决方案:

NSString *stringURL = @"http://www.amazon.co.uk/gp/rss/bestsellers/books/72/ref=zg_bs_72_rsslink";
NSURL  *url = [NSURL URLWithString:stringURL];
NSData *htmlData = [NSData dataWithContentsOfURL:url];

TFHpple * doc = [[TFHpple alloc] initWithHTMLData:htmlData];

NSArray *titleElements = [doc searchWithXPathQuery:@"//span[@class='riRssTitle']/a"];
for (TFHppleElement *element in titleElements)
{
    NSString *title = element.firstChild.content;
    NSLog(@"title: %@", title);
}

NSArray *imageElements = [doc searchWithXPathQuery:@"//a[@class='url']/img"];
for (TFHppleElement *element in imageElements)
{
    NSString *image = element.attributes[@"src"];
    NSMutableArray *parts = [[image componentsSeparatedByString:@"/"] mutableCopy];
    NSArray *pathParts = [parts.lastObject componentsSeparatedByString:@"."];
    [parts removeLastObject];
    [parts addObject:[NSString stringWithFormat:@"%@.%@",pathParts.firstObject, pathParts.lastObject]];
    image = [parts componentsJoinedByString:@"/"];
    NSLog(@"image: %@", image);
}

NSArray *authorElements = [doc searchWithXPathQuery:@"//span[@class='riRssContributor']/a"];
for (TFHppleElement *element in authorElements)
{
    NSString *author = element.firstChild.content;
    NSLog(@"author: %@", author);
}

NSArray *priceElements = [doc searchWithXPathQuery:@"//font/b"];
for (TFHppleElement *element in priceElements)
{
    NSString *price = element.firstChild.content;
    NSLog(@"price: %@", price);
}

NSArray *ratingElements = [doc searchWithXPathQuery:@"//img"];
for (TFHppleElement *element in ratingElements)
{
    if (![element.attributes[@"src"] containsString:@"stars"])
        continue;

    NSArray *parts = [element.attributes[@"src"] componentsSeparatedByString:@"-"];
    if (parts.count < 5) continue;

    NSString *rating = [NSString stringWithFormat:@"%@.%@", parts[3], [parts[4] substringToIndex:1]];
    NSLog(@"rating: %@", rating);
}

如您所说，您受制于亚马逊的命名惯例。