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Editor to share with you what is the use of the Javasax parser in Java, I believe most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to know it!

SAX (a simple API for XML) is a parser for XML documents based on events. Unlike DOM parsers, SAX parsers create no parse trees. SAX is a streaming interface for XML, which means that the SAX application is used to receive event notification about the elements of the XML document being processed, attributes, starting sequentially each time at the top of the document, and ending the root element with the closure.

Read the XML file from top to bottom to form a well-structured XML document markup

Tokens are processed in the same order, and they appear in the document

Report applications because of the nature of the tags encountered by the parser where they appear

The application provides the necessary parser registered "event" handlers

As a tag identification, the information related to the callback method in the handler is called

When will you use it?

When you should use the SAX parser:

Can be processed from top to bottom in XML documents in a linear manner

The file is not deeply nested

Dealing with a very large XML document, the DOM tree takes up too much memory. A typical implementation of DOM uses 10 bytes of memory to represent a byte of XML

Part of the XML document involved in solving the problem

The data is available, as long as it is seen by the parser, such a SAX can be well used to reach the XML document of the stream

Shortcomings of SAX

It is a XML document that only enters to handle random access.

If the data analyzer you need to track has seen or changed the order of the items, you must write your own code and data store

ContentHandler interface

This interface specifies that the SAX parser is used to notify the XML document that you have seen the callback method of the widget application.

VoidstartDocument ()-the call is at the beginning of a file.

VoidendDocument ()-the call is at the end of a file.

VoidstartElement (Stringuri,StringlocalName,StringqName,Attributesatts)-the call is at the beginning of an element.

VoidendElement (Stringuri,StringlocalName,StringqName)-call at the end of a component.

Voidcharacters (char [] ch,intstart,intlength)-called when character data is present.

VoidignorableWhitespace (char [] ch,intstart,intlength)-called when DTD is current and ignore whitespace encounters.

VoidprocessingInstruction (Stringtarget,Stringdata)-called when processing the approval of an instruction.

VoidsetDocumentLocator (Locatorlocator))-provides locators that can be used to identify locations in a document.

VoidskippedEntity (Stringname)-called when an unresolved entity encounters.

VoidstartPrefixMapping (Stringprefix,Stringuri)-when a new namespace mapping definition is called.

VoidendPrefixMapping (Stringprefix)-called when a namespace definition ends its scope.

Attribute interface

This interface specifies the method used to handle attributes connected to an element.

IntgetLength ()-returns the number of attributes.

StringgetQName (intindex)

StringgetValue (intindex)

StringgetValue (Stringqname)

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