Parsing XML (in-depth knowledge and basic usage)

1 year ago
Liam
2 minutes

XML, or Extensible Markup Language, is a markup language used for storing and transmitting data. It utilizes customized tags to describe the structure and content of the data, providing excellent readability and scalability.

XML parsing is the process of converting an XML document into a manipulable data structure, allowing it to be read, modified, and handled. Common XML parsing methods include DOM parsing and SAX parsing.

DOM parsing (Document Object Model parsing) involves loading the entire XML document into memory and constructing a tree structure document object model (DOM) which can be traversed to access and manipulate the content of the XML document. DOM parsing is suitable for small XML documents, but may use up a lot of memory for large documents.

SAX parsing, which stands for Simple API for XML parsing, is an event-driven parsing method that reads XML documents line by line and triggers events to parse the document. Unlike other methods, SAX parser does not build a complete DOM tree during the parsing process, but instead reads and processes the XML document content line by line as needed. SAX parsing is suitable for large XML documents as it requires less memory.

The fundamental usage of DOM parsing is as follows:

  1. Import the relevant libraries for the DOM parser.
  2. Create a DocumentBuilder object.
  3. Use the parse() method of the DocumentBuilder object to parse an XML file into a Document object.
  4. Use the methods of the Document object to retrieve the root node of an XML document, then traverse the child nodes of the root node to access and manipulate the content of the XML document.

Here is a basic usage of SAX parsing:

  1. Import the relevant libraries for the SAX parser.
  2. Instantiate a SAXParser object.
  3. Create a custom handler class that extends DefaultHandler, and override the relevant methods to process the content of an XML document.
  4. Parse the XML file into an input stream using the parse() method of the SAXParser object, and pass it to a custom handler class for parsing.

Both DOM and SAX parsing require writing corresponding code to parse and handle XML documents based on their structure and content. For specific usage instructions and code examples, refer to the relevant programming language documentation and tutorials.

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