PHP扩展之XML操作（三）——XML解析器使用及相关函数

时间：2017-02-13 15:02

一、XML 元素结构例程

第一个例程缩进显示文档中的开始元素结构。

Example #1 显示 XML 元素结构

<?php$file = "data.xml";$depth = array();
function startElement($parser, $name, $attrs){
global $depth;
for ($i = 0; $i < $depth[$parser]; $i++) 
{
echo "  ";
}
echo "$name\n";
$depth[$parser]++;
}
function endElement($parser, $name){
global $depth;
$depth[$parser]--;
}
$xml_parser = xml_parser_create();
xml_set_element_handler($xml_parser, "startElement", "endElement");
if (!($fp = fopen($file, "r"))) 
{die("could not open XML input");
}
while ($data = fread($fp, 4096)) 
{
if (!xml_parse($xml_parser, $data, feof($fp))) {
die(sprintf("XML error: %s at line %d",xml_error_string(xml_get_error_code($xml_parser)),
xml_get_current_line_number($xml_parser)));
}
}xml_parser_free($xml_parser);
?>

二、XML 标签映射例程

Example #1 将 XML 映射为 HTML

此例程直接地将 XML 标签映射为 HTML 标签。在“map_array”中未找到的元素将被忽略。当然，此例程只针对特定的 XML 文档类型起作用。

<?php$file = "data.xml";
$map_array = array("BOLD"     => "B","EMPHASIS" => "I","LITERAL"  => "TT");
function startElement($parser, $name, $attrs){
global $map_array;
if (isset($map_array[$name])) {
echo "<$map_array[$name]>";
}
}
function endElement($parser, $name){global $map_array;
if (isset($map_array[$name])) {
echo "</$map_array[$name]>";}
}
function characterData($parser, $data){
echo $data;
}
$xml_parser = xml_parser_create();
// use case-folding so we are sure to find the tag in 
$map_arrayxml_parser_set_option($xml_parser, XML_OPTION_CASE_FOLDING, true);
xml_set_element_handler($xml_parser, "startElement", "endElement");
xml_set_character_data_handler($xml_parser, "characterData");
if (!($fp = fopen($file, "r"))) 
{die("could not open XML input");
}
while ($data = fread($fp, 4096)) {
if (!xml_parse($xml_parser, $data, feof($fp))) {
die(sprintf("XML error: %s at line %d",
xml_error_string(xml_get_error_code($xml_parser)),
xml_get_current_line_number($xml_parser)));}
}
xml_parser_free($xml_parser);
?>

三、XML 外部实体例程

此例程用于加亮 XML 代码。举例说明如何使用外部实体引用来包含和解析其他文档，及处理指令是如何被处理的，及判断处理指令所包含代码是否“可信任”的一种方法

用于此例程的 XML 文档位于此例程的下方( 和 )。

Example #1 外部实体例程

<?php$file = "xmltest.xml";
function trustedFile($file){
// 仅信任本地文件
if (!preg_match("@^([a-z]+)\:\/\/@i", $file)&& fileowner($file) == getmyuid()) {return true;}return false;}
function startElement($parser, $name, $attribs){
echo "&lt;<font color=\"#0000cc\">$name</font>";
if (count($attribs)) {
foreach ($attribs as $k => $v) {
echo " <font color=\"#009900\">$k</font>=\"<fontcolor=\"#990000\">$v</font>\"";}}
echo "&gt;";
}
function endElement($parser, $name){
echo "&lt;/<font color=\"#0000cc\">$name</font>&gt;";
}
function characterData($parser, $data){
echo "<b>$data</b>";
}
function PIHandler($parser, $target, $data){
switch (strtolower($target)) {case "php":global $parser_file;
// 如何要解析的文档是“可信任”的, 则说明可安全// 地执行其内部的 PHP 代码。否则，显示代码内容。
if (trustedFile($parser_file[$parser])) {
eval($data);
} 
else {printf("Untrusted PHP code: <i>%s</i>",htmlspecialchars($data));
}
break;}}
function defaultHandler($parser, $data){
if (substr($data, 0, 1) == "&" && substr($data, -1, 1) == ";") {
printf('<font color="#aa00aa">%s</font>',htmlspecialchars($data));
} 
else {printf('<font size="-1">%s</font>',htmlspecialchars($data));}}
function externalEntityRefHandler($parser, $openEntityNames, $base, $systemId,$publicId) {
if ($systemId) {if (!list($parser, $fp) = new_xml_parser($systemId)) {printf("Could not open entity %s at %s\n", $openEntityNames,$systemId);
return false;}while ($data = fread($fp, 4096)) {if (!xml_parse($parser, $data, feof($fp))) {
printf("XML error: %s at line %d while parsing entity %s\n",xml_error_string(xml_get_error_code($parser)),xml_get_current_line_number($parser), 
$openEntityNames);xml_parser_free($parser);return false;}}xml_parser_free($parser);return true;}return false;}
function new_xml_parser($file){global $parser_file;
$xml_parser = xml_parser_create();xml_parser_set_option($xml_parser, XML_OPTION_CASE_FOLDING, 1);
xml_set_element_handler($xml_parser, "startElement", "endElement");
xml_set_character_data_handler($xml_parser, "characterData");
xml_set_processing_instruction_handler($xml_parser, "PIHandler");
xml_set_default_handler($xml_parser, "defaultHandler");
xml_set_external_entity_ref_handler($xml_parser, "externalEntityRefHandler");
if (!($fp = @fopen($file, "r"))) {return false;}
if (!is_array($parser_file)) {settype($parser_file, "array");}$parser_file[$xml_parser] = $file;
return array($xml_parser, $fp);}
if (!(list($xml_parser, $fp) = new_xml_parser($file))) {die("could not open XML input");}
echo "<pre>";
while ($data = fread($fp, 4096)) {
if (!xml_parse($xml_parser, $data, feof($fp))) {
die(sprintf("XML error: %s at line %d\n",
xml_error_string(xml_get_error_code($xml_parser)),
xml_get_current_line_number($xml_parser)));}}
echo "</pre>";echo "parse complete\n";
xml_parser_free($xml_parser);
?>

Example #2 xmltest.xml

<?xml version='1.0'?>
<!DOCTYPE chapter SYSTEM "/just/a/test.dtd" [
<!ENTITY plainEntity "FOO entity">
<!ENTITY systemEntity SYSTEM "xmltest2.xml">
]>
<chapter>
 <TITLE>Title &plainEntity;</TITLE>
 <para>
  <informaltable>
   <tgroup cols="3">
    <tbody>
     <row><entry>a1</entry><entry morerows="1">b1</entry><entry>c1</entry></row>
     <row><entry>a2</entry><entry>c2</entry></row>
     <row><entry>a3</entry><entry>b3</entry><entry>c3</entry></row>
    </tbody>
   </tgroup>
  </informaltable>
 </para>
 &systemEntity;
 <section id="about">
  <title>About this Document</title>
  <para>
   <!-- this is a comment -->
   <?php echo 'Hi!  This is PHP version ' . phpversion(); ?>
  </para>
 </section>
</chapter>

此文件包含在中:

Example #3 xmltest2.xml

<?xml version="1.0"?>
<!DOCTYPE foo [
<!ENTITY testEnt "test entity">
]>
<foo>
   <element attrib="value"/>
   &testEnt;
   <?php echo "This is some more PHP code being executed."; ?>
</foo>