1# XML Generation 2 3 4XML is a widely supported data exchange format used by various systems and applications. For example, web services often transmit structured data in XML format. 5 6 7XML can also serve as a messaging format for communication between nodes in distributed systems. 8 9 10## Precautions 11 12- XML tags must always appear in pairs: one start tag and one end tag. 13 14- XML tags are case sensitive, meaning that the case of the start and end tags must match. 15 16 17## How to Develop 18 19The XML module provides the **XmlSerializer** class to generate XML data. This class takes a fixed-length ArrayBuffer or DataView object as input, which is used to store the generated XML data. 20 21You can call various methods to write different content. For example, call **startElement(name: string)** to write the start tag of an element and **setText(text: string)** to write the tag value. 22 23For details about the APIs of the XML module, see [@ohos.xml (XML Parsing and Generation)](../reference/apis-arkts/js-apis-xml.md). By calling the appropriate functions as needed, you can generate a complete XML document. 24 251. Import the module. 26 27 ```ts 28 import { xml, util } from '@kit.ArkTS'; 29 ``` 30 312. Create a buffer and construct an XmlSerializer object, either based on an ArrayBuffer or a DataView object. 32 33 ```ts 34 // Method 1: Create an XmlSerializer object based on ArrayBuffer. 35 let arrayBuffer: ArrayBuffer = new ArrayBuffer(2048); // Create a 2048-byte ArrayBuffer. 36 let serializer: xml.XmlSerializer = new xml.XmlSerializer(arrayBuffer); // Create an XmlSerializer object based on the ArrayBuffer. 37 38 // Method 2: Create an XmlSerializer object based on DataView. 39 // let arrayBuffer: ArrayBuffer = new ArrayBuffer(2048); 40 // let dataView: DataView = new DataView(arrayBuffer); 41 // let serializer: xml.XmlSerializer = new xml.XmlSerializer(dataView); 42 ``` 43 443. Call the functions to generate XML data. 45 46 ```ts 47 serializer.setDeclaration(); // Write the XML declaration. 48 serializer.startElement('bookstore'); // Write the start tag of an element. 49 serializer.startElement('book'); // Write the start tag of a nested element. 50 serializer.setAttributes('category', 'COOKING'); // Write attributes and attribute values. 51 serializer.startElement('title'); 52 serializer.setAttributes('lang', 'en'); 53 serializer.setText('Everyday'); // Write the tag value. 54 serializer.endElement(); // Write the end flag. 55 serializer.startElement('author'); 56 serializer.setText('Giana'); 57 serializer.endElement(); 58 serializer.startElement('year'); 59 serializer.setText('2005'); 60 serializer.endElement(); 61 serializer.endElement(); 62 serializer.endElement(); 63 ``` 64 654. Use **Uint8Array** to manipulate the ArrayBuffer, use **TextDecoder** to decode the Uint8Array, and output it. 66 67 ```ts 68 let uint8Array: Uint8Array = new Uint8Array(arrayBuffer); // Use Uint8Array to read data from the ArrayBuffer. 69 let textDecoder: util.TextDecoder = util.TextDecoder.create(); // Call the TextDecoder class of the util module. 70 let result: string = textDecoder.decodeToString(uint8Array); // Decode the Uint8Array. 71 console.info(result); 72 ``` 73 74 The output is as follows: 75 76 ``` 77 <?xml version="1.0" encoding="utf-8"?><bookstore> 78 <book category="COOKING"> 79 <title lang="en">Everyday</title> 80 <author>Giana</author> 81 <year>2005</year> 82 </book> 83 </bookstore> 84 ``` 85