PHP xmlwriter_start_dtd()用法及代码示例

定义和用法

XML 是一种 mark-up 语言，用于在网络上共享数据，XML 用于人类 read-able 和机器 read-able。 XMLWriter 扩展内部具有 libxml xmlWriter API，用于编写/创建 XML 文档的内容。由此生成的 XML 文档是非缓存的和 forward-only。

这个xmlwriter_start_dtd()函数用于创建 DTD 标记的开始。

用法

xmlwriter_start_dtd($writer, $name, $public_id, $system_id);

参数

Sr.No	参数及说明
1	writer(Mandatory) 这是 XMLWriter 类的一个对象，表示您要修改/创建的 XML 文档。
2	name(Mandatory) 这是一个字符串值，表示文档类型的限定名称。
3	public_id(Optional) 这是一个字符串值，表示文档类型的限定名称。
4	system_id(Optional) 这是一个字符串值，表示文档类型的限定名称。

返回值

此函数返回一个布尔值，成功时为 TRUE，失败时为 FALSE。

PHP版本

这个函数最初是在 PHP 版本 5 中引入的，并且适用于所有后续版本。

示例

下面的例子演示了xmlwriter_start_dtd()函数 -

<?php
   //Opening a writer
   $uri = "result.xml";
   $writer = xmlwriter_open_uri($uri);

   //Starting the document
   xmlwriter_start_document($writer);

   //Starting the Dtd tag
   xmlwriter_start_dtd($writer, 'test_dtd', 'pub_1001', 'sys_1001');

   //Ending the Dtd tag
   xmlwriter_end_dtd($writer); 
   xmlwriter_set_indent($writer, TRUE);
   xmlwriter_set_indent_string($writer, "    ");

   //Starting an element
   xmlwriter_start_element($writer, 'Tutorial');

   //Starting a element tag
   xmlwriter_start_element($writer, 'name');

   //Adding text to the element
   xmlwriter_text($writer, 'JavaFX');  
   xmlwriter_end_element($writer);
   xmlwriter_start_element($writer, 'Author');
   
   //Adding text to the element
   xmlwriter_text($writer, 'Krishna');  
   xmlwriter_end_element($writer);

   //Ending the element
   xmlwriter_end_element($writer);

   //Ending the document
   xmlwriter_end_document($writer);
?>

这将生成以下 XML 文档 -

<?xml version="1.0"?>
<!DOCTYPE test_dtd PUBLIC "pub_1001" "sys_1001"><Tutorial>
   <name>JavaFX</name>
   <Author>Krishna</Author>
</Tutorial>

示例

以下是面向对象风格的此函数的示例 -

<?php
   //Creating an XMLWriter
   $writer = new XMLWriter();

   //Opening a writer
   $uri = "result.xml";
   $writer->openUri($uri);

   //Starting the document
   $writer->startDocument();

   //Setting the indentation on
   $writer->setIndent(TRUE);
   
   //Setting the indentation
   $writer->setIndentString("    ");

   //Starting the Dtd tag
   $writer->startDtd('test_dtd', 'pub_1001', 'sys_1001');

   //Ending the Dtd tag
   $writer->endDtd(); 

   //Starting an element
   $writer->startElement('Tutorial');
   $writer->startElement('name');
   
   //Adding text to the element
   $writer->text('JavaFX');  
   $writer->endElement();
   $writer->startElement('Author');
   
   //Adding text to the element
   $writer->text('Krishna');  
   $writer->endElement();

   //Ending the element
   $writer->endElement();
   
   //Ending the document
   $writer->endDocument();
?>

这将生成以下 XML 文档 -

<?xml version="1.0"?>
<!DOCTYPE test_dtd PUBLIC "pub_1001" "sys_1001">
<Tutorial>
   <name>JavaFX</name>
   <Author>Krishna</Author>
</Tutorial>