Php 简明教程

PHP - DOM Parser Example

PHP 中的 DOM 扩展提供广泛的功能，我们可借此对 XML 和 HTML 文档执行各种操作。我们可以动态构造一个 DOM 对象，从一个 HTML 文件或包含 HTML 标记树的字符串加载一个 DOM 文档。我们还可以将 DOM 文档保存到 XML 文件中，或者从 XML 文档中提取 DOM 树。

The DOM extension in PHP comes with extensive functionality with which we can perform various operations on XML and HTML documents. We can dynamically construct a DOM object, load a DOM document from a HTML file or a string with HTML tag tree. We can also save the DOM document to a XML file, or extract the DOM tree from a XML document.

DOMDocument 类是 DOM 扩展中定义的最重要类之一。

The DOMDocument class is one the most important classes defined in the DOM extension.

$obj = new DOMDocument($version = "1.0", $encoding = "")

它表示整个 HTML 或 XML 文档；用作文档树的根。DOMDocument 类包括许多静态方法的定义，其中一些如下 -

It represents an entire HTML or XML document; serves as the root of the document tree. The DOMDocument class includes definitions of a number of static methods, some of which are introduced here −

Sr.No	Methods & Description
1	createElement Create new element node
2	createAttribute Create new attribute
3	createTextNode Create new text node
4	getElementById Searches for an element with a certain id
5	getElementsByTagName Searches for all elements with given local tag name
6	load Load XML from a file
7	loadHTML Load HTML from a string
8	loadHTMLFile Load HTML from a file
9	loadXML Load XML from a string
10	save Dumps the internal XML tree back into a file
11	saveHTML Dumps the internal document into a string using HTML formatting
12	saveHTMLFile Dumps the internal document into a file using HTML formatting
13	saveXML Dumps the internal XML tree back into a string

Example

让我们对以下 HTML 文件使用此示例 −

Let us use the following HTML file for this example −

<html>
<head>
   <title>Tutorialspoint</title>
</head>
<body>
   <h2>Course details</h2>
   <table border = "0">
      <tbody>
         <tr>
            <td>Android</td>
            <td>Gopal</td>
            <td>Sairam</td>
         </tr>
         <tr>
            <td>Hadoop</td>
            <td>Gopal</td>
            <td>Satish</td>
         </tr>
         <tr>
            <td>HTML</td>
            <td>Gopal</td>
            <td>Raju</td>
         </tr>
         <tr>
            <td>Web technologies</td>
            <td>Gopal</td>
            <td>Javed</td>
         </tr>
         <tr>
            <td>Graphic</td>
            <td>Gopal</td>
            <td>Satish</td>
         </tr>
         <tr>
            <td>Writer</td>
            <td>Kiran</td>
            <td>Amith</td>
         </tr>
         <tr>
            <td>Writer</td>
            <td>Kiran</td>
            <td>Vineeth</td>
         </tr>
      </tbody>
   </table>
</body>
</html>

我们现在将通过在以下 PHP 代码中调用 loadHTMLFile() 方法从上述 HTML 文件中提取文档对象模型 −

We shall now extract the Document Object Model from the above HTML file by calling the loadHTMLFile() method in the following PHP code −

<?php

   /*** a new dom object ***/
   $dom = new domDocument;

   /*** load the html into the object ***/
   $dom->loadHTMLFile("hello.html");

   /*** discard white space ***/
   $dom->preserveWhiteSpace = false;

   /*** the table by its tag name ***/
   $tables = $dom->getElementsByTagName('table');

   /*** get all rows from the table ***/
   $rows = $tables[0]->getElementsByTagName('tr');

   /*** loop over the table rows ***/
   foreach ($rows as $row) {

      /*** get each column by tag name ***/
      $cols = $row->getElementsByTagName('td');

      /*** echo the values ***/
      echo 'Designation: '.$cols->item(0)->nodeValue.'<br />';
      echo 'Manager: '.$cols->item(1)->nodeValue.'<br />';
      echo 'Team: '.$cols->item(2)->nodeValue;
      echo '<hr />';
   }

?>

它将生成以下 output −

It will produce the following output −

Designation: Android
Manager: Gopal
Team: Sairam
________________________________________
Designation: Hadoop
Manager: Gopal
Team: Satish
________________________________________
Designation: HTML
Manager: Gopal
Team: Raju
________________________________________
Designation: Web technologies
Manager: Gopal
Team: Javed
________________________________________
Designation: Graphic
Manager: Gopal
Team: Satish
________________________________________
Designation: Writer
Manager: Kiran
Team: Amith
________________________________________
Designation: Writer
Manager: Kiran
Team: Vineeth
________________________________________