长沙北大青鸟作者:科泰校区cyman20(翻译)
筑巢时间(Nesting Time)
前面的例子只是用来说明问题的。如果你真想把RDF内容插入到Web站点当中,就需要把事情做的更好一些。所以把前面的脚本的作了改进,新增了一些东西,从而简化格式化RDF数据的任务。
<html>
<head>
<basefont face="Verdana">
</head>
<body>
<table border="0" cellspacing="5" cellpadding="5">
<tr>
<td><b>New releases on freshmeat.net today:</b></td>
</tr>
<?php
// XML file
$file = "http://www.freshmeat.net/backend/fm-releases.rdf";
// set up some variables for use by the parser
$currentTag = "";
$flag = "";
$count = 0;
// this is an associative array of channel data with keys ("title",
"link",
"description")
$channel = array();
// this is an array of arrays, with each array element representing an
<item> // each outer array element is itself an associative array
// with keys ("title", "link", "description")
$items = array();
// opening tag handler
function elementBegin($parser, $name, $attributes)
{
global $currentTag, $flag;
$currentTag = $name;
// set flag if entering <channel> or <item> block
if ($name == "ITEM")
{
$flag = 1;
}
else if ($name == "CHANNEL")
{
$flag = 2;
}
}
// closing tag handler
function elementEnd($parser, $name)
{
global $currentTag, $flag, $count;
$currentTag = "";
// set flag if exiting <channel> or <item> block
if ($name == "ITEM")
{
$count++;
$flag = 0;
}
else if ($name == "CHANNEL")
{
$flag = 0;
}
}
// character data handler
function characterData($parser, $data)
{
global $currentTag, $flag, $items, $count, $channel;
$data = trim(htmlspecialchars($data));
if ($currentTag == "TITLE" || $currentTag == "LINK" ||
$currentTag ==
"DESCRIPTION")
{
// add data to $channels[] or $items[] array
if ($flag == 1)
{
$items[$count][strtolower($currentTag)] .=
$data;
}
else if ($flag == 2)
{
$channel[strtolower($currentTag)] .= $data;
}
}
}
// create parser
$xp = xml_parser_create();
// set element handler
xml_set_element_handler($xp, "elementBegin", "elementEnd");
xml_set_character_data_handler($xp, "characterData");
xml_parser_set_option($xp, XML_OPTION_CASE_FOLDING, TRUE);
xml_parser_set_option($xp, XML_OPTION_SKIP_WHITE, TRUE);
// read XML file
if (!($fp = fopen($file, "r")))
{
die("Could not read $file");
}
// parse data
while ($xml = fread($fp, 4096))
{
if (!xml_parse($xp, $xml, feof($fp)))
{
die("XML parser error: " .
xml_error_string(xml_get_error_code($xp)));
}
}
// destroy parser
xml_parser_free($xp);
// now iterate through $items[] array
// and print each item as a table row
foreach ($items as $item)
{
echo "<tr><td><a href=" . $item["link"] . ">" . $item["title"] .
"</a><br>" . $item["description"] . "</td></tr>"; }
?>
</table>
</body>
</html>
与先前的那段的主要区别在于,这段脚本创建了两个数组,用于保存分析过程中所提取的信息。其中,$channel是联合性数组(associative array),存放被处理的频道的基本描述信息,而$items是一个二维数组,包含关于单独的频道条目(channel intems)的信息。$items数组中的每一个元素本身又是一个联合性数组,包含title,URL和description关键字。$items数组中元素总数与RDF文档中的<item>区块总数相同。
还需注意$flag变量的变化,根据被处理的是<channel></channel>区块还是<item></item>区块,它现在保存两个值。这一点很有必要,因为只有这样,分析器才能把信息放入正确的数组里面。
一旦文档分析完毕,事情就简单了——遍历$items 数组,以表格形式打印其中的每一个条目(item)。