php – 如何从DBLP中提取最新文章

我需要从DBLP中提取最新的文章

所有元素的描述和所有字段都可以在以下位置找到：

http://dblp.uni-trier.de/xml/dblp.dtd

帮助文件位于：

http://dblp.uni-trier.de/xml/docu/dblpxml.pdf

那么,你有一个API,你按年份做GET请求,你得到一个JSON文档;

我想从今天的文章中获得一个JSON文档;

但我不知道如何使用mdate属性发出GET请求;

这是一篇文章的结构：

<article key="journals/cacm/Szalay08"
mdate="2008-11-03">
<author>Alexander S. Szalay</author>
<title>Jim Gray, astronomer.</title>
<pages>58-65</pages>
<year>2008</year>
<volume>51</volume>
<journal>Commun. ACM</journal>
<number>11</number>
<ee>http://doi.acm.org/10.1145/
1400214.1400231</ee>
<url>db/journals/cacm/
cacm51.html#Szalay08</url>
</article>

我试过这个http://dblp.uni-trier.de/rec/bibtex/journals/acta/BayerM72并得到：

<?xml version="1.0"?>
<dblp>
<article key="journals/acta/BayerM72"
mdate="2003-11-25">
<author>Rudolf Bayer</author>
<author>Edward M. McCreight</author>
<title>Organization and Maintenance
of Large Ordered Indices</title>
...
</article>
</dblp>

我需要使用字段mdate提取所有最新文章.

这是一篇关于各种要求的文章：http://dblp.uni-trier.de/xml/docu/dblpxmlreq.pdf

php代码：

<pre>
    <?php
    $url = 'http://dblp.uni-trier.de/rec/bibtex/';
    $key = 'journals/acta/BayerM72';
    $content = file_get_contents($url . $key);
    echo $content;
    ?>
</pre>

解决方法:

对于解析xml,有XML Parser,XMLReader和SimpleXML.XML Parser和XMLReader用于大文件,SimpleXML – 用于小文件(< 1Mb).

function startElement($parser, $tag, $attrs) {
    global $articles, $isArticle, $i, $globTag;
    $globTag = $tag;
    if ($tag == 'article') {
        $isArticle = true;
        if (isset ( $attrs ['mdate'] )) {
            // add date from attribute in article
            $articles [$i] ['mdate'] = $attrs ['mdate'];
        }
    }
}
function endElement($parser, $tag) {
    global $articles, $isArticle, $i, $globTag;
    if ($tag == 'article') {
        $isArticle = false;
        ++ $i;
    }
}
function getElement($parser, $data) {
    global $articles, $isArticle, $i, $globTag;
    if ($isArticle) {
        $articles [$i] = $articles [$i] + [ 
                $globTag => $data 
        ];
    }
}
global $articles, $isArticle, $i, $globTag;
$articles = [ ];
$i = 0;
$isArticle = false;
$url = 'http://dblp.uni-trier.de/rec/bibtex/';
$key = 'journals/acta/BayerM72';
$url .= $key;
$parser = xml_parser_create ();

xml_set_element_handler ( $parser, "startElement", "endElement" );
xml_set_character_data_handler ( $parser, 'getElement' );
xml_parser_set_option ( $parser, XML_OPTION_CASE_FOLDING, false );

$file = fopen ( $url, 'rb' );
if ($file === false) {
    die ( "File isnt!!" );
}
$clasterSize = 8192;

while ( $data = fread ( $file, $clasterSize ) ) {
    if (! xml_parse ( $parser, $data, feof ( $file ) )) {
        die ( sprintf ( "XML error: %s at line %d", xml_error_string ( xml_get_error_code ( $parser ) ), xml_get_current_line_number ( $parser ) ) );
    }
}
xml_parser_free ( $parser );
fclose ( $file );

这是XML Parser中的示例.

<?php
    $url = 'http://dblp.uni-trier.de/rec/bibtex/';
    $key = 'journals/acta/BayerM72';
    $content = file_get_contents($url . $key);
$xml = new SimpleXMLElement($content);

/* Search for <dblp><article> */
$result = $xml->xpath('/dblp/article');
// $result is  an array of SimpleXMLElement objects
   var_dump($result);
    ?>

有SimpleXML示例.您在结果中获得了一个SimpleXMLElement对象数组.查看manual以获取SimpleXMLElement属性SimpleXMLElement-> attributes();.

标签：php,xml,semantics
来源： https://codeday.me/bug/20190629/1322112.html