php clean html 可以设置过滤及保留属性
类：
<?phpfunction reg_escape( $str ){$conversions = array( "^" => "\^", "[" => "\[", "." => "\.", "$" => "\$", "{" => "\{", "*" => "\*", "(" => "\(", "\" => "\\\", "/" => "\/", "+" => "\+", ")" => "\)", "|" => "\|", "?" => "\?", "<" => "\<", ">" => "\>" );return strtr( $str, $conversions );}/*** Strip attribute Class* Remove attributes from XML elements* @author David (semlabs.co.uk)* @version 0.2.1*/class cleanHtml{public $str= '';public $allow= array();public $exceptions= array();public $ignore= array();public function strip( $str ){$this->str = $str;if( is_string( $str ) && strlen( $str ) > 0 ){$res = $this->findElements();if( is_string( $res ) )return $res;$nodes = $this->findAttributes( $res );$this->removeAttributes( $nodes );}return $this->str;}private function findElements(){# Create an array of elements with attributes$nodes = array();preg_match_all( "/<([^ !\/\>\n]+)([^>]*)>/i", $this->str, $elements );foreach( $elements[1] as $el_key => $element ){if( $elements[2][$el_key] ){$literal = $elements[0][$el_key];$element_name = $elements[1][$el_key];$attributes = $elements[2][$el_key];if( is_array( $this->ignore ) && !in_array( $element_name, $this->ignore ) )$nodes[] = array( 'literal' => $literal, 'name' => $element_name, 'attributes' => $attributes );}}# Return the XML if there were no attributes to removeif( !$nodes[0] )return $this->str;elsereturn $nodes;}private function findAttributes( $nodes ){# Extract attributesforeach( $nodes as &$node ){preg_match_all( "/([^ =]+)\s*=\s*["|']{0,1}([^"']*)["|']{0,1}/i", $node['attributes'], $attributes );if( $attributes[1] ){foreach( $attributes[1] as $att_key => $att ){$literal = $attributes[0][$att_key];$attribute_name = $attributes[1][$att_key];$value = $attributes[2][$att_key];$atts[] = array( 'literal' => $literal, 'name' => $attribute_name, 'value' => $value );}}else$node['attributes'] = null;$node['attributes'] = $atts;unset( $atts );}return $nodes;}private function removeAttributes( $nodes ){# Remove unwanted attributesforeach( $nodes as $node ){# Check if node has any attributes to be kept$node_name = $node['name'];$new_attributes = '';if( is_array( $node['attributes'] ) ){foreach( $node['attributes'] as $attribute ){if( ( is_array( $this->allow ) && in_array( $attribute['name'], $this->allow ) ) || $this->isException( $node_name, $attribute['name'], $this->exceptions ) )$new_attributes = $this->createAttributes( $new_attributes, $attribute['name'], $attribute['value'] );}}$replacement = ( $new_attributes ) ? "<$node_name $new_attributes>" : "<$node_name>";$this->str = preg_replace( '/'. reg_escape( $node['literal'] ) .'/', $replacement, $this->str );}}private function isException( $element_name, $attribute_name, $exceptions ){if( array_key_exists($element_name, $this->exceptions) ){if( in_array( $attribute_name, $this->exceptions[$element_name] ) )return true;}return false;}private function createAttributes( $new_attributes, $name, $value ){if( $new_attributes )$new_attributes .= " ";$new_attributes .= "$name="$value"";return $new_attributes;}}?实例：
$str = 'Here is some sample html that is <span id="good" style="abc" font="3"> <font color="red"> getting broken </font> </span> <iframe width="540" height="304" src="http://www.youtube.com/embed/YacZqlFz2bI?fs=1&feature=oembed" frameborder="0" allowfullscreen></iframe> <img id="featuredon" src="http://www.goodfinancialcents.com/wp-content/themes/thesis_182/custom/images/featuredon.jpg" height="23" width="265" />';$sa = new cleanHtml;$sa->allow = array( 'id' ); $sa->exceptions = array( 'img' => array( 'src', 'alt' ), 'a' => array( 'href', 'title' ),'iframe'=>array('src','frameborder'), );echo $str = $sa->strip( $str ); ?来源：semlabs.co.uk
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