### 如何用 PHP 把 RDF 内容插入 Web 站点之中(5)

if (!($fp = fopen($this->file, "r")))
{
die("Could not read $this->file"),
}
// parse data
while ($xml = fread($fp, 4096))
{
if (!xml_parse($this->xp, $xml, feof($fp)))
{
die("XML parser error: " .
xml_error_string(xml_get_error_code($this->xp))),
}
}
// destroy parser
xml_parser_free($this->xp),
}
// opening tag handler
function elementBegin($parser, $name, $attributes)
{
$this->currentTag = $name,
// set flag if entering <channel> or <item> block
if ($name == "ITEM")
{
$this->flag = 1,
}
else if ($name == "CHANNEL")
{
$this->flag = 2,
}
}
// closing tag handler
function elementEnd($parser, $name)
{
$this->currentTag = "",
// set flag if exiting <channel> or <item> block
if ($name == "ITEM")
{
$this->count++,
$this->flag = 0,
}
else if ($name == "CHANNEL")
{
$this->flag = 0,
}
}
// character data handler
function characterData($parser, $data)
{
$data = trim(htmlspecialchars($data)),
if ($this->currentTag == "TITLE" || $this->currentTag ==
"LINK" || $this->currentTag == "DESCRIPTION")
{
// add data to $channels[] or $items[] array
if ($this->flag == 1)
{
$this->items[$this->count][strtolower($this->currentTag)] .= $data,
}
else if ($this->flag == 2)
{
$this->channel[strtolower($this->currentTag)] .= $data,
}
}
}
// return an associative array containing channel information
// (the $channel[] array)
function getChannelInfo()
{
return $this->channel,
}
// return an associative array of arrays containing item
information
// (the $items[] array)
function getItems()
{
return $this->items,
}
}
?>
如果你对ＰＨＰ类较为熟悉的话，那么理解这段代码是相当容易的。如果不太懂的话，那么请直接跳到文章末尾的链接部分，看一篇关于类工作原理的好文章。然后在回来继续阅读上面的代码。
在使用这个类之前，我要特别花几分钟指出其中的一行代码——即上面对 xml_set_object()函数调用的那一行。
现在的问题是如何使用这个类实际生成具有多个内容来源的 Web 页。
<?
include("class.RDFParser.php"),
// how many items to display in each channel
$maxItems = 5,
?>
<html>
<head>
<basefont face="Verdana">
<body>
<table width="100%" border="0" cellspacing="5" cellpadding="5"> <tr>
<!-- first cell -->
<td valign=top align=left>
<font size="-1">
<?
// get and parse freshmeat.net channel
$f = new RDFParser(),
$f->setResource("http://www.freshmeat.net/backend/fm-releases.rdf"),
$f->parseResource(),
$f_channel = $f->getChannelInfo(),
$f_items = $f->getItems(),
// now format and print it...
?>
The latest from <a href=<? echo $f_channel["link"], ?>><? echo
$f_channel["title"], ?></a> <br> <ul> <? // iterate through items array
for ($x=0, $x<$maxItems, $x++) {
if (is_array($f_items[$x]))
{
// print data
$item = $f_items[$x],
echo "<li><a href=" . $item["link"] . ">" .
$item["title"] . "</a>",
}
}
?>
</ul>
</font>
</td>
<!-- second cell -->
<td align=center width=50%>
<i>Primary page content here</i>
</td>
<!-- third cell -->
<td valign=top align=left>
<font size="-1">
<?
// get and parse slashdot.org channel
$s = new RDFParser(),
$s->setResource("http://slashdot.org/slashdot.rdf"),
$s->parseResource(),
$s_channel = $s->getChannelInfo(),
$s_items = $s->getItems(),
// now format and print it...
?>
The latest from <a href=<? echo $s_channel["link"], ?>><? echo
$s_channel["title"], ?></a> <br> <ul> <? // iterate through items array
for ($x=0, $x<$maxItems, $x++) {
if (is_array($s_items[$x]))
{
// print data
$item = $s_items[$x],
echo "<li><a href=" . $item["link"] . ">" .
$item["title"] . "</a>",
}
}
?>
</ul>
</font>
</td>
</tr>
</table>
</body>
</head>
</html>
这段代码相当简单。一旦你用“new”关键字生成一个类的实例，
$f = new RDFParser(),
那么就可以用类方法来设置要分析的 RDF 文件的位置，
$f->setResource("http://www.freshmeat.net/backend/fm-releases.rdf"),
$f->parseResource(),
并且获取$channel 和$items 数组，以用于后面的处理。
<?
$f_channel = $f->getChannelInfo(),
$f_items = $f->getItems(),
?>
The latest from <a href=<? echo $f_channel["link"], ?>><? echo
$f_channel["title"], ?></a> <br> <ul> <? // iterate through items array
for ($x=0, $x<$maxItems, $x++) {
if (is_array($f_items[$x]))
{
// print data
$item = $f_items[$x],