PHP uses SAX to parse XML implementation code and problem analysis

PHP uses SAX to parse XML implementation code and problem analysis_PHP tutorial

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Release： 2016-07-21 15:25:18

Original

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复制代码代码如下:

 
$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

复制代码代码如下:

 
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

复制代码代码如下:

 
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

复制代码代码如下:

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

In the final result, the data in the summary is much less, and the complete summary content is never obtained. Sometimes I get garbled codes, and even after searching online for a long time, I still don’t know what is causing the problem.
Later I discovered that the problem was because xml_parser parsed XML and processed the data in the node in a loop, and only took about 300 characters in length each time (I don’t know the specific length, but I just used strlen to output about 300) , then I realized that it was because each cycle would overwrite the previous data, which would cause the problem of incomplete data.
The solution is to change $this->data[$this->i][$tagname] = $cdata; in the cdata method in the xml class in the xml_class file to $this->data[$ this->i][$tagname] .= $cdata; can be solved (there are some NOTICE errors, which PHP has ignored).