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PHP用SAX解析XML的实现代码与问题分析

WBOY
Release: 2016-06-06 20:38:33
Original
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近日在做一个解析XML的小程序,因为服务器是PHP4的,XML解析函数只能用SAX方式的xml_parser来解析了。

代码如下:
$g_books = array();
$g_elem = null;
function startElement( $parser, $name, $attrs )
{
global $g_books, $g_elem;
if ( $name == 'BOOK' ) $g_books []= array();
$g_elem = $name;
}
function endElement( $parser, $name )
{
global $g_elem;
$g_elem = null;
}
function textData( $parser, $text )
{
global $g_books, $g_elem;
if ( $g_elem == 'AUTHOR' ||
$g_elem == 'PUBLISHER' ||
$g_elem == 'TITLE' )
{
$g_books[ count( $g_books ) - 1 ][ $g_elem ] = $text;
}
}
$parser = xml_parser_create();
xml_set_element_handler( $parser, "startElement", "endElement" );
xml_set_character_data_handler( $parser, "textData" );
$f = fopen( 'books.xml', 'r' );
while( $data = fread( $f, 4096 ) )
{
xml_parse( $parser, $data );
}
xml_parser_free( $parser );
foreach( $g_books as $book )
{
echo $book['TITLE']." - ".$book['AUTHOR']." - ";
echo $book['PUBLISHER']."\n";
}
?>

PHP中用SAX方式解析XML发现的问题
XML如下:
so.xml
代码如下:



1047869
2008-08-28 14:54:51
红花还需绿叶扶--浅谈脚架云台的选购
很多专业摄影师在选购三脚架的时候,往往出手阔绰,3、4000元一个的捷信或者曼富图三脚架常常不用经过思考就买下来了,可是,他们却总是忽视了云台的精挑细眩其实,数码相机架在三脚架上面究竟稳不稳,起决定作用的是云台,那么我们如何才能挑选到一款稳如磐石的云台呢?云台家族种类繁多用途迥异简单的说,脚架云台是用于连接相机与脚架进行角度调节的部件,主要分成三维云台和球型云台。三维云台在横向旋转

...(省略若干行)


xml_class.php
代码如下:
class xml {
var $parser;
var $i =0;
var $search_result = array();
var $row = array();
var $data = array();
var $now_tag;
var $tags = array("ID", "CLASSID", "SUBCLASSID", "CLASSNAME", "TITLE", "SHORTTITLE", "AUTHOR", "PRODUCER", "SUMMARY", "CONTENT", "DATE");
function xml()
{
$this->parser = xml_parser_create();
xml_set_object($this->parser, $this);
xml_set_element_handler($this->parser, "tag_open", "tag_close");
xml_set_character_data_handler($this->parser, "cdata");
}
function parse($data)
{
xml_parse($this->parser, $data);
}
function tag_open($parser, $tag, $attributes)
{
$this->now_tag=$tag;
if($tag=='RESULT') {
$this->search_result = $attributes;
}
if($tag=='ROW') {
$this->row[$this->i] = $attributes;
}
}
function cdata($parser, $cdata)
{
if(in_array($this->now_tag, $this->tags)){
$tagname = strtolower($this->now_tag);
$this->data[$this->i][$tagname] = $cdata;
}
}
function tag_close($parser, $tag)
{
$this->now_tag="";
if($tag=='ROW') {
$this->i++;
}
}
}
?>

search.php
代码如下:
require_once("./xml_class.php");
$xml = file_get_contents("./so.xml");
$xml_parser = new xml();
$xml_parser->parse($xml);
print_r($xml_parser);
?>

最后得到的结果中summary中的数据少了很多,总是得不到完整的summary内容。有时还会得到乱码,在网上也找了半天也不知道是什么问题引起的。
  后来才发现问题是因为xml_parser解析XML是循环处理节点中的数据的,每次只取大概300个字符长度(具体是多少,我也不太清楚,只是用strlen输出大概在300左右),于是才知道是因为每次的循环就会把前次的数据给复盖了,这样就会出现数据不全的问题。
  解决办法就是把xml_class文件中的xml类中的cdata方法中$this->data[$this->i][$tagname] = $cdata;改为$this->data[$this->i][$tagname] .= $cdata;即可解决(其中有一些NOTICE错误,PHP已忽略了).
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