php读取xml文件的三种实现方法

<?php
$doc = new DOMDocument();
$doc->load(&#39;books.xml&#39;);
$books = $doc->getElementsByTagName("book");
foreach ($books as $book) {
    $authors = $book->getElementsByTagName("author");
    $author = $authors->item(0)->nodeValue;
    $publishers = $book->getElementsByTagName("publisher");
    $publisher = $publishers->item(0)->nodeValue;
    $titles = $book->getElementsByTagName("title");
    $title = $titles->item(0)->nodeValue;
    echo "$title - $author - $publisher/n";
}
?>

<?php
$xml = "";
$f = fopen(&#39;books.xml&#39;, &#39;r&#39;);
while ($data = fread($f, 4096)) {
    $xml.= $data;
}
fclose($f);
preg_match_all("//<book/>(.*?)/<//book/>/s", $xml, $bookblocks);
foreach ($bookblocks[1] as $block) {
    preg_match_all("//<author/>(.*?)/<//author/>/", $block, $author);
    preg_match_all("//<title/>(.*?)/<//title/>/", $block, $title);
    preg_match_all("//<publisher/>(.*?)/<//publisher/>/", $block, $publisher);
    echo ($title[1][0] . " - " . $author[1][0] . " - " . $publisher[1][0] . "/n");
}
?>

<books> 
  <book> 
  <author>Jack Herrington</author> 
  <title>PHP Hacks</title> 
  <publisher>O&#39;Reilly</publisher> 
  </book> 
  <book> 
  <author>Jack Herrington</author> 
  <title>Podcasting Hacks</title> 
  <publisher>O&#39;Reilly</publisher> 
  </book> 
</books>

<?php
$parser = xml_parser_create(); //创建一个parser编辑器
xml_set_element_handler($parser, "startElement", "endElement"); //设立标签触发时的相应函数 这里分别为startElement和endElenment
xml_set_character_data_handler($parser, "characterData"); //设立数据读取时的相应函数
$xml_file = "1.xml"; //指定所要读取的xml文件,可以是url
$filehandler = fopen($xml_file, "r"); //打开文件
while ($data = fread($filehandler, 4096)) {
    xml_parse($parser, $data, feof($filehandler));
} //每次取出4096个字节进行处理
fclose($filehandler);
xml_parser_free($parser); //关闭和释放parser解析器
$name = false;
$position = false;
function startElement($parser_instance, $element_name, $attrs) //起始标签事件的函数
{
    global $name, $position;
    if ($element_name == "NAME") {
        $name = true;
        $position = false;
        echo "名字:";
    }
    if ($element_name == "POSITION") {
        $name = false;
        $position = true;
        echo "职位:";
    }
}
function characterData($parser_instance, $xml_data) //读取数据时的函数
{
    global $name, $position;
    if ($position) echo $xml_data . "<br>";
    if ($name) echo $xml_data . "<br>";
}
function endElement($parser_instance, $element_name) //结束标签事件的函数
{
    global $name, $position;
    $name = false;
    $position = false;
}
?>

<?xml version="1.0" 
<employees> 
<employee> 
<name>张三</name> 
<position age="45">经理</position> 
</employee> 
<employees> 
<employee> 
<name>李四</name> 
<position age="45">助理</position> 
</employee> 
</employees>