Kotlin SAX Parser

SAX (Simple API for XML) is a widely-used approach for parsing XML documents in a streaming manner. In Kotlin, you can leverage the SAX parser to efficiently process XML data. This guide covers the basics of using the SAX parser in Kotlin.

Syntax

import org.xml.sax.Attributes
import org.xml.sax.InputSource
import org.xml.sax.helpers.DefaultHandler
import javax.xml.parsers.SAXParserFactory

val saxParser = SAXParserFactory.newInstance().newSAXParser()
val handler = MySAXHandler() // Your custom handler class
val inputStream = // Provide your XML input stream
saxParser.parse(InputSource(inputStream), handler)

Example

import org.xml.sax.Attributes
import org.xml.sax.InputSource
import org.xml.sax.helpers.DefaultHandler
import javax.xml.parsers.SAXParserFactory
import java.io.StringReader

class MySAXHandler : DefaultHandler() {
    override fun startElement(uri: String?, localName: String?, qName: String?, attributes: Attributes?) {
        // Handle start element event
    }

    override fun characters(ch: CharArray?, start: Int, length: Int) {
        // Handle character data
    }

    override fun endElement(uri: String?, localName: String?, qName: String?) {
        // Handle end element event
    }
}

fun main() {
    val xmlData = "<root><element>Value</element></root>"
    val saxParser = SAXParserFactory.newInstance().newSAXParser()
    val handler = MySAXHandler()
    val inputStream = InputSource(StringReader(xmlData))
    saxParser.parse(inputStream, handler)
}

Output

The output depends on your implementation of the MySAXHandler class. In this example, the SAX events are handled within the overridden methods.

Explanation

• The SAX parser processes XML data in a stream, invoking callbacks for specific events (start element, characters, end element, etc.).
• MySAXHandler is a custom class that extends DefaultHandler and overrides methods to handle SAX events.
• The XML input source can be provided from various sources, such as a file, network, or string.

Use

Use the Kotlin SAX parser when:

• You need to process large XML documents efficiently.
• Streaming processing is suitable for your use case.
• You want fine-grained control over handling XML events.

Important Points

• Implement a custom DefaultHandler to handle SAX events according to your XML structure.
• Create an instance of SAXParser using SAXParserFactory.
• Use the parser to parse an InputSource containing your XML data.

Summary

The Kotlin SAX parser is a powerful tool for efficiently processing XML data in a streaming fashion. By implementing a custom handler, you can tailor the parsing logic to suit the structure of your XML documents. Consider using SAX when dealing with large XML datasets or when a streaming approach is preferred.