PHP5中的SimpleXML解析XML文档

   用PHP5中的SimpleXML解析XML文档:
    messages.xml文件内容如下:
    <?xml version=“1.0” ?>
    <!--Sample XML document -->
    <SystemMessage>
    <MessageTitle>System Down for Maintenance</MessageTitle>
    <MessageBody>Going down for maintenance soon!</MessageBody>
    <MessageAuthor>
    <MessageAuthorName>Joe SystemGod</MessageAuthorName>
    <MessageAuthorEmail>systemgod@someserver.com
    </MessageAuthorEmail>
    </MessageAuthor>
    <MessageDate>March 4, 2004</MessageDate>
    <MessageNumber>10</MessageNumber>
    </SystemMessage>
    xml 是一种创建元数据的语言,元数据是描述其它数据的数据,PHP中的XML处理是基于LIBXML2的,安装时默认开启.
    可以通过phpinfo()函数查看是否开启了XML处理模块,DOM,LIBXML,SAMPLEXML.
    首先,通过samplexml_load_file函数把xml文件加载到一个对象中,samplexml_load_file可以用户远程文件.
    例如:
    $xml = samplexml_load_file(“messages.xml”); // 本地文件系统,当前目录
    $xml = samplexml_load_file(“phpzixue.cn/rss1.xml”); // 远程web服务器
    用 var_dump($xml) 和 print_r($xml) 分别输出其结构.var_dump给出了变量的类型和长度,而print_r可读性更强输出对象中的所有元素名称和它的值.
    echo $xml->MessageTitle; //输出消息的标题
    echo $xml->MessageBody; // 输出消息体
    echo $xml->MessageAuthor; //消息的作者
    echo $xml->MessageDate;  // 消息产生的日期
    echo $xml->MessageNumber;  // 消息代码
    另外,还有一个函数,可以把XML字符串加载到一个simplexml对象中取.
    以下为引用的内容:
    $channel =<<<_XML_
    <channel>
    <title>What's For Dinner</title>
    <link>menu.example.com/</link>
    <description>These are your choices of what to eat tonight. </description>
    </channel>
    _XML_;
    $xml = simplexml_load_string($channel);
    rss.xml
    <?xml version=“1.0” encoding=“utf-8”?>
    <rss version=“0.91”>
    <channel>
    <title>What's For Dinner</title>
    <link>menu.example.com/</link>
    <description>These are your choices of what to eat tonight.</description>
    <item>
    <title>Braised Sea Cucumber</title>
    <link>http://menu.example.com/dishes.php?dish=cuke</link>
    <description>Gentle flavors of the sea that nourish and refresh you. </description>
    </item>
    <item>
    <title>Baked Giblets with Salt</title>
    <link>menu.example./dishes.php?dish=giblets</link>
    <description>Rich giblet flavor infused with salt and spice. </description>
    </item>
    <item>
    <title>Abalone with Marrow and Duck Feet</title>
    <link>menu.example./dishes.php?dish=abalone</link>
    <description>There's no mistaking the special pleasure of abalone. </description>
    </item>
    </channel>
    </rss>