The most efficient way to parse xml

XML is widely used in various developments, and Android is no exception. As an important role in carrying data, how to read and write XML has become an important skill in Android development. Today I will introduce to you several common XML parsing and creation methods on the Android platform.

In Android, common XML parsers are SAX parser, DOM parser and PULL parser. Below, I will give you a detailed introduction.

SAX parser:

SAX(Simple API for XML) parser is an event-based parser. Its core is the event processing mode, which mainly works around event sources and event processors. When the event source generates an event, call the corresponding processing method of the event processor, and an event can be processed. When the event source calls a specific method in the event handler, it must also pass the status information of the corresponding event to the event handler, so that the event handler can decide its own behavior based on the provided event information.

The advantage of the SAX parser is that it has fast parsing speed and takes up less memory. Perfect for use in Android mobile devices.

DOM parser:

DOM is a collection of nodes or information fragments based on a tree structure, allowing developers to use DOM The API traverses the XML tree and retrieves the required data. Analyzing this structure typically requires loading the entire document and constructing a tree structure before node information can be retrieved and updated.

Since DOM is stored in a tree structure in memory, retrieval and update efficiency will be higher. But for particularly large documents, parsing and loading the entire document will be resource-intensive.

PULL parser:

The PULL parser operates similarly to SAX, both are event-based. The difference is that during the PULL parsing process, we need to obtain the generated events ourselves and then perform corresponding operations, unlike SAX where the processor triggers an event and executes our code. The PULL parser is small and lightweight, has fast parsing speed, is simple and easy to use, and is very suitable for use in Android mobile devices. The PULL parser is also used internally in the Android system when parsing various XML.

In Android, the first choice is of course the pull parser. The PULL parser is small and lightweight, has fast parsing speed, is simple and easy to use, and is very suitable for use in Android mobile devices. The Android system also uses the PULL parser when parsing various XMLs. Android officials recommend developers to use Pull parsing technology. Pull parsing technology is an open source technology developed by a third party, and it can also be applied to JavaSE development.

How PULL works:

XML pull provides a start element and an end element. When an element starts, you can call parser. nextText extracts all character data from the XML document. When a document is parsed to the end, the EndDocument event is automatically generated.

Commonly used XML pull interfaces and classes:

XmlPullParser: This parser is an interface with parsing function defined in org.xmlpull.v1.

XmlSerializer: It is an interface that defines the sequence of XML information sets.

XmlPullParserFactory: This class is used to create XML in XMPULL V1 API Pull parser.

XmlPullParserException: Throws a single XML pull parser related error.

The PULL parser operates similarly to SAX, both are event-based.

The difference is that numbers are returned during the PULL parsing process, and we need to obtain the generated events ourselves and then perform corresponding operations, unlike SAX where the processor triggers an event and executes Our code:

Read the xml declaration and return START_DOCUMENT; end and return END_DOCUMENT ; Start tag returns START_TAG;

End tag returns END_TAG; Text returns TEXT.

Finally, make a comparison and summary of these three parsing technologies:
For Android mobile devices, because the resources of the device are relatively precious and the memory is limited, we need to choose the appropriate technology. Parse XML, which helps improve access speed.

When DOM processes an XML file, it parses the XML file into a tree structure and puts it into memory for processing. When the XML file is small, we can choose DOM because it is simple and intuitive.

SAX uses events as a mode for parsing XML files. It converts XML files into a series of events, and different event processors decide how to process them. When the XML file is large, it is more reasonable to choose SAX technology. Although the code size is somewhat large, it does not require loading all XML files into memory. This is more efficient with limited Android memory, and Android provides a traditional way to use SAX as well as a convenient SAX wrapper. Using Xml classes is simpler than using SAX.

XML Pull parsing does not listen to the end of the element like SAX parsing, but does most of the processing at the beginning. This is beneficial to reading XML files early and can greatly reduce parsing time. This optimization is particularly important for mobile devices with slow connection speeds. For XML documents that are large but only a portion of the document is needed, XML Pull parsers are a more efficient approach.

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