PHP generates XML simple example code_PHP tutorial-PHP Tutorial-php.cn

When working with XML-based applications, developers often need to create XML-encoded data structures. For example, XML status templates in the Web based on user input, server request XML statements, and client responses based on runtime parameters.
Although the construction of XML data structure is time-consuming, if you use the mature PHP DOM application programming interface, everything will become simple and clear. This article will introduce you to the main functions of the PHP DOM application interface and demonstrate how to generate a correct complete XML file and save it to disk.
Create a document type declaration
Generally speaking, XML declarations are placed at the top of the document. Declaration in PHP is very simple: just instantiate an object of the DOM document class and give it a version number. View program listing A:
Program listing A

Copy code The code is as follows:

 
 // create doctype 
$dom = new DOMDocument("1.0"); 
// display document in browser as plain text 
// display document in browser as plain text 
// for readability purposes 
header("Content-Type: text/plain"); 
// save and display tree 
echo $dom->saveXML(); 
?> 

Please note the saveXML() method of the DOM document object. I'll go into more detail about this method later, but for now you just need to briefly realize that it is used to output the current snapshot of the XML document to a file or browser. In this example, I've output the ASCII text directly to the browser to enhance readability. In practical applications, text/XML header files can be sent to the browser.
If you view the output in a browser, you can see the following code:

Add elements and text nodes
The truly powerful feature of XML is Content from its elements and encapsulation. Fortunately, once you initialize the DOM document, many operations become very simple. This process includes the following two steps:
For each element or text node you want to add, call the createElement() or createTextNode() method of the DOM document object through the element name or text content. This creates a new object corresponding to the element or text node.
Add an element or text node to a parent node in the XML document tree by calling the node's appendChild() method, passing it the object created in the previous step.
The following example will clearly demonstrate these 2 steps, please see Listing B.
Program List B

Copy code The code is as follows:

 
// create doctype 
$dom = new DOMDocument("1.0"); 
// display document in browser as plain text 
// for readability purposes 
header("Content-Type: text/plain"); 
// create root element 
$root = $dom->createElement("toppings"); 
$dom->appendChild($root); 
// create child element 
 $item = $dom->createElement("item"); 
$root->appendChild($item); 
// create text node 
$text = $dom->createTextNode( "pepperoni"); 
$item->appendChild($text); 
// save and display tree 
echo $dom->saveXML(); 
?> 
 

Here, I first create a root element named and place it in the XML header file. Then, I create an element named and make it the root element. Finally, I create another text node with a value of "pepperoni" and assign it to the element. The final result is as follows:

Copy code The code is as follows:

pepperoni

If you want to add another topping, just create another Program List C

Copy code The code is as follows:

 
// create doctype 
$dom = new DOMDocument("1.0"); 
// display document in browser as plain text 
// for readability purposes 
header("Content-Type: text/plain"); 
// create root element 
$root = $dom->createElement("toppings"); 
$dom->appendChild($root); 
// create child element 
 $item = $dom->createElement("item"); 
$root->appendChild($item); 
// create text node 
$text = $dom->createTextNode( "pepperoni"); 
$item->appendChild($text); 
// create child element 
$item = $dom->createElement("item"); 
$root ->appendChild($item); 
// create another text node 
$text = $dom->createTextNode("tomato"); 
$item->appendChild($text); 
// save and display tree 
echo $dom->saveXML(); 
?> 

The following is the output after executing program listing C:

Copy the code The code is as follows:

 
pepperoni 
tomato

Add attributes
By using attributes, you can also add appropriate information to elements. For the PHP DOM API, adding an attribute requires two steps: first use the createAttribute() method of the DOM document object to create a node with the attribute name, and then add the document node to the attribute node with the attribute value. See Listing D for details.
Program List D

Copy code The code is as follows:

 
// create doctype 
$dom = new DOMDocument("1.0"); 
// display document in browser as plain text 
// for readability purposes 
header("Content-Type: text/plain"); 
// create root element 
$root = $dom->createElement("toppings"); 
$dom->appendChild($root); 
// create child element 
 $item = $dom->createElement("item"); 
$root->appendChild($item); 
// create text node 
$text = $dom->createTextNode( "pepperoni"); 
$item->appendChild($text); 
// create attribute node 
$price = $dom->createAttribute("price"); 
$item ->appendChild($price); 
// create attribute value node 
$priceValue = $dom->createTextNode("4"); 
$price->appendChild($priceValue); 
// save and display tree 
echo $dom->saveXML(); 
?> 

The output is as follows:

Copy code The code is as follows:

pepperoni

Add CDATA module and process wizard
Although the CDATA module and process wizard are not often used, by calling The createCDATASection() and createProcessingInstruction() methods of the DOM document object, and the PHP API can also support CDATA and process wizards well, see Program Listing E.
Program List E

Copy code The code is as follows:

 
// create doctype 
// create doctype 
$dom = new DOMDocument("1.0"); 
// display document in browser as plain text 
// for readability purposes 
header("Content-Type: text/plain"); 
// create root element 
$root = $dom->createElement("toppings"); 
$dom->appendChild($root); 
/ / create child element 
$item = $dom->createElement("item"); 
$root->appendChild($item); 
// create text node 
$text = $dom->createTextNode("pepperoni"); 
$item->appendChild($text); 
// create attribute node 
$price = $dom->createAttribute("price" ); 
$item->appendChild($price); 
// create attribute value node 
$priceValue = $dom->createTextNode("4"); 
$price-> ;appendChild($priceValue); 
// create CDATA section 
$cdata = $dom->createCDATASection(" Customer requests that pizza be sliced ​​into 16 square pieces "); 
$root-> appendChild($cdata); 
// create PI 
$pi = $dom->createProcessingInstruction("pizza", "bake()"); 
$root->appendChild($pi) ; 
// save and display tree 
echo $dom->saveXML(); 
?> 

The output is as follows:

Copy code The code is as follows:

 
pepperoni 
Customer requests that pizza be sliced ​​into 16 square pieces 
]]>

Saving Results
Once you have achieved your goal, you can save the results in a file or store them in a PHP variable. The results can be saved in a file by calling the save() method with the file name, or in a PHP variable by calling the saveXML() method. Please refer to the following example (Program List F):
Program List F

Copy the code The code is as follows:

 
// create doctype 
$dom = new DOMDocument("1.0"); 
// create root element 
$root = $dom->createElement("toppings"); 
$dom->appendChild($root); 
$dom->formatOutput=true; 
// create child element 
$item = $dom->createElement("item"); 
$root->appendChild($item); 
// create text node 
$text = $dom->createTextNode("pepperoni"); 
$item->appendChild($text); 
// create attribute node 
$price = $dom->createAttribute("price"); 
$item->appendChild($price); 
// create attribute value node 
$priceValue = $dom->createTextNode("4"); 
$price->appendChild($priceValue); 
// create CDATA section 
$cdata = $dom->createCDATASection(" Customer requests that pizza be 
sliced into 16 square pieces "); 
$root->appendChild($cdata); 
// create PI 
$pi = $dom->createProcessingInstruction("pizza", "bake()"); 
$root->appendChild($pi); 
// save tree to file 
$dom->save("order.xml"); 
// save tree to string 
$order = $dom->save("order.xml"); 
?> 

下面是实际的例子，大家可以测试下。
xml.php(生成xml)

复制代码代码如下:

 
$conn = mysql_connect('localhost', 'root', '123456') or die('Could not connect: ' . mysql_error()); 
mysql_select_db('vdigital', $conn) or die ('Can't use database : ' . mysql_error()); 
$str = "SELECT id,username FROM `admin` GROUP BY `id` ORDER BY `id` ASC"; 
$result = mysql_query($str) or die("Invalid query: " . mysql_error()); 
if($result) 
{ 
$xmlDoc = new DOMDocument(); 
if(!file_exists("01.xml")){ 
$xmlstr = ""; 
$xmlDoc->loadXML($xmlstr); 
$xmlDoc->save("01.xml"); 
} 
else { $xmlDoc->load("01.xml");} 
$Root = $xmlDoc->documentElement; 
while ($arr = mysql_fetch_array($result)){ 
$node1 = $xmlDoc->createElement("id"); 
$text = $xmlDoc->createTextNode(iconv("GB2312","UTF-8",$arr["id"])); 
$node1->appendChild($text); 
$node2 = $xmlDoc->createElement("name"); 
$text2 = $xmlDoc->createTextNode(iconv("GB2312","UTF-8",$arr["username"])); 
$node2->appendChild($text2); 
$Root->appendChild($node1); 
$Root->appendChild($node2); 
$xmlDoc->save("01.xml"); 
} 
} 
mysql_close($conn); 
?> 

test.php(应用测试)

复制代码代码如下:

 
$xmlDoc = new DOMDocument(); 
$xmlDoc->load("http://localhost/xml/xml.php"); 
$x=$xmlDoc->getElementsByTagName('name'); 
for ($i=0; $i<=$x->length-1; $i++) 
{ 
if(strpos($x->item($i)->nodeValue,"fang")!==false) 
{ 
echo $x->item($i)->parentNode->childNodes->item(1)->nodeValue; 
} 
} 
?> 