The comparison of the XML PULL parsing API framework and other XML parsing methods
The comparison of the XML PULL parsing API framework and other XML parsing methods
preface:
With the rapid development of the Internet, XML (scalable markings), as a common format for data exchange and storage, has been widely used.In Java development, analysis of XML data is a common demand.This article will compare the XML PULL parsing API framework and other XML parsing methods to discuss their hierarchical structure, performance and usage scenarios, and provide corresponding Java code examples.
1. XML PULL parsing API framework
The XML PULL parsing API framework is an event -based XML parsing method.Compared with other analysis methods, XML Pull provides a simpler and more efficient way to resolve XML data.It accesses XML elements one by one in order, rather than loading the entire document to the memory to reduce memory overhead and increase the resolution speed.The following is the key category of XML PULL parsing API:
-Xmlpullparser: The parser interface defines a series of methods to read the XML event one by one, such as starting labels, ending tags, text content, etc.
-XMLPULLLPARSERFACTORY: The factory class used to create an XMLPULLPARSER instance.
The advantages of XML PULL parsing the API framework include:
-Lightweight: XML PULL parser is a lightweight library that does not rely on any third -party library.
-Hir -efficient performance: Because the XML PULL parser reads the XML event one by one, instead of loading the entire document at one time, it can have higher performance and lower memory overhead when processing large XML files.
-It is easy to use: provided simple and intuitive APIs, easy to use and integrate into existing projects.
The following is an example code that uses XML PULL to analyze the API to analyze the XML document:
try {
XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
XmlPullParser parser = factory.newPullParser();
// Set the XML input source, which can be file, network flow, etc.
InputStream inputStream = new FileInputStream("data.xml");
parser.setInput(inputStream, null);
int eventType = parser.getEventType();
while (eventType != XmlPullParser.END_DOCUMENT) {
switch (eventType) {
case XmlPullParser.START_TAG:
String tagName = parser.getName();
if ("person".equals(tagName)) {
String name = parser.getAttributeValue(null, "name");
System.out.println("Name: " + name);
}
break;
case XmlPullParser.END_TAG:
break;
case XmlPullParser.TEXT:
String text = parser.getText();
System.out.println("Text: " + text);
break;
}
eventType = parser.next();
}
inputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
2. DOM parser
DOM (Document Object Model) parser loads the entire XML document to the memory and constructs a tree structure to represent the XML document.The DOM parser provides a complete access ability to XML trees, which can be randomly access and modify any XML element.However, due to loading the entire document to the memory, the processing of large XML files may cause the problem of high memory consumption.
The following is an example code using a DOM parser to parse the XML document:
try {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
// Load the XML document
Document document = builder.parse(new File("data.xml"));
NodeList nodeList = document.getElementsByTagName("person");
for (int i = 0; i < nodeList.getLength(); i++) {
Node node = nodeList.item(i);
if (node.getNodeType() == Node.ELEMENT_NODE) {
Element element = (Element) node;
String name = element.getAttribute("name");
System.out.println("Name: " + name);
NodeList childNodes = element.getChildNodes();
for (int j = 0; j < childNodes.getLength(); j++) {
Node childNode = childNodes.item(j);
if (childNode.getNodeType() == Node.TEXT_NODE) {
String text = childNode.getTextContent();
System.out.println("Text: " + text);
}
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
3. SAX parser
SAX (Simple API For XML) parser is a XML parsing method based on event -driven, similar to the XML Pull analysis API.The SAX parser handles the XML document by triggering the event, read it one by one, and can only record the data of interest.The SAX parser does not load the entire XML document into the memory like the DOM parser, so the memory consumption is less.
The following is a sample code that uses the SAX parser to analyze the XML document:
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
try {
SAXParserFactory factory = SAXParserFactory.newInstance();
SAXParser saxParser = factory.newSAXParser();
// Create custom processing procedures for realizing defaultHandler
DefaultHandler handler = new DefaultHandler() {
boolean isPerson = false;
@Override
public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
if ("person".equals(qName)) {
isPerson = true;
String name = attributes.getValue("name");
System.out.println("Name: " + name);
}
}
@Override
public void endElement(String uri, String localName, String qName) throws SAXException {
if (isPerson) {
isPerson = false;
}
}
@Override
public void characters(char[] ch, int start, int length) throws SAXException {
if (isPerson) {
String text = new String(ch, start, length);
System.out.println("Text: " + text);
}
}
};
// Start parsing XML document
saxParser.parse(new File("data.xml"), handler);
} catch (Exception e) {
e.printStackTrace();
}
Comparison and summary:
-The XML PULL parsing API framework and SAX parser are both event -driven parsing methods. You can read XML documents one by one to avoid loading the entire document into memory.Therefore, they have low memory consumption and high performance when processing large XML files.
-Compared with the XML PULL parsing API framework, the API of the SAX parser may be more complicated to use.
-DOM parser loads the entire XML document to the memory, providing a complete access ability to XML tree, but it may cause the memory to consume too much when processing large XML files.
-We using a DOM parser is usually suitable for scenarios to modify or access the entire XML document; and use the XML Pull to parse the API framework or SAX parser to the scene where only analysis, reading or traversing XML data.
-Ap parsing the API framework for most common XML parsing tasks for most common XML parsing tasks is a good choice. It is both lightweight and efficient.
I hope this article will help you understand the comparison of the XML PULL parsing API framework and other XML parsing methods.
