PHP XML 操作類實現：從構建到輸出的完整封裝

PHP XML 操作類實現：從構建到輸出的完整封裝

本文提供一個純 PHP 實現的 XML 操作類，支持文檔聲明、根節點、屬性、子節點、CDATA 區塊的靈活構建，並提供文件保存與直接輸出功能。雖然現代項目推薦使用 DOMDocument 或 SimpleXML 內置擴展，但該類展示了手動拼接 XML 的核心邏輯，適合學習理解 XML 結構生成原理。

類核心功能

• 初始化 XML 版本、編碼、RSS 結構
• 設置根元素 (root())
• 添加根子節點 (append_root_node()) 及屬性
• 添加子節點 (append_child_node()) 支持 CDATA
• 節點關閉 (append_root_node_end())
• 輸出 HTTP Header 並打印 (display())
• 保存至文件 (save())
• 字符過濾 (filter()) 防止非法字符破壞結構

完整類代碼

';
    private $rssEnd = '';

    public function __construct($version = '1.0', $encoding = 'UTF-8') {
        $this->version = $version;
        $this->encoding = $encoding;
    }

    public function newFile($filename) {
        $this->filename = $filename;
        return true;
    }

    public function root($element) {
        $element = $this->filter($element);
        if ($this->rootStart) {
            throw new Exception('XML 只允許一個根元素');
        }
        $this->rootStart = "<{$element}>";
        $this->rootEnd = "";
        $this->xml = "version}\" encoding=\"{$this->encoding}\" standalone=\"yes\"?>\n{$this->rssStart}\n{$this->rootStart}\n";
        return true;
    }

    public function appendRootNode($title, $property = null, $proVal = null) {
        $title = $this->filter($title);
        $property = $this->filter($property);
        $proVal = $this->filter($proVal);
        $attr = $property ? " {$property}=\"{$proVal}\"" : '';
        $this->xml .= "<{$title}{$attr}>\n";
        $this->rootEnd = "";
        return true;
    }

    public function appendRootNodeEnd() {
        $this->xml .= "{$this->rootEnd}\n";
        return true;
    }

    public function appendChildNode($title = 'undefined', $content = 'undefined', $property = null, $proVal = null, $cdata = false) {
        $title = $this->filter($title);
        $content = $this->filter($content, false);
        $property = $this->filter($property);
        $proVal = $this->filter($proVal);
        $attr = $property ? " {$property}=\"{$proVal}\"" : '';
        
        if ($cdata) {
            $this->xml .= "<{$title}{$attr}>\n";
        } else {
            $this->xml .= "<{$title}{$attr}>{$content}\n";
        }
        return true;
    }

    public function display() {
        header("Content-Type: text/xml; charset={$this->encoding}");
        echo $this->xml . $this->rootEnd . "\n" . $this->rssEnd;
    }

    public function save() {
        $fullXml = $this->xml . $this->rootEnd . "\n" . $this->rssEnd;
        $handle = fopen($this->filename, 'wb+');
        $result = fwrite($handle, $fullXml);
        fclose($handle);
        if (!$result) {
            throw new Exception("寫入文件失敗，請檢查目錄權限");
        }
        return true;
    }

    private function filter($string, $removeSpace = true) {
        $filters = ['"', "'", "\n", "\r", "\t"];
        if ($removeSpace) $filters[] = ' ';
        return str_replace($filters, '', $string);
    }
}

使用示例

$xml = new XMLBuilder();
$xml->newFile('test.xml');
$xml->root('document');

$xml->appendRootNode('book');
$xml->appendChildNode('author', 'linage');
$xml->appendChildNode('page', 100);
$xml->appendChildNode('money', '35 RMB');
$xml->appendRootNodeEnd();

$xml->appendRootNode('book', 'name', 'The Web Servers');
$xml->appendChildNode('author', 'linage');
$xml->appendChildNode('page', 100);
$xml->appendChildNode('money', '35 RMB');
$xml->appendRootNodeEnd();

$xml->display();  // 瀏覽器直接查看
$xml->save();     // 保存文件

生成的 XML 結構

linage
100
35 RMB


linage
100
35 RMB

現代替代方案推薦

DOMDocument 等價實現片段

$dom = new DOMDocument('1.0', 'UTF-8');
$dom->formatOutput = true;
$rss = $dom->createElement('rss');
$rss->setAttribute('version', '2.0');
$dom->appendChild($rss);

$doc = $dom->createElement('document');
$rss->appendChild($doc);

$book = $dom->createElement('book');
$book->setAttribute('name', 'The Web Servers');
$doc->appendChild($book);

$author = $dom->createElement('author', 'linage');
$book->appendChild($author);
// ... 其他節點
echo $dom->saveXML();

總結

手工拼接 XML 類適合教學與極簡場景，但缺乏對實體轉義、命名空間、Schema 驗證的完善支持。實際項目中請優先使用 DOMDocument 或 XMLWriter，確保輸出合規、安全且高效。