Android simplifies XML sax parsing

Dom parsing takes up a lot of memory (I need to parse a variety of KML files, sometimes the 4-5m KML file uses the DOM to parse a lot of phones out of memory), and we need to introduce a third-party library, so it's a good choice to use a sax parsing that saves lots of memory and does not need to introduce other libraries. Because Sax is particularly troublesome in parsing complex XML files, it organizes a tool that simplifies the parsing of Android Sax.

Implementation idea: As with the Android touch event delivery mechanism, the node that needs to parse the sub-parser is passed down.

If there is a further simplification of the method, Welcome to Exchange! Email:[email protected].

Example program: Https://github.com/John-Chen/EasySaxParser

Simplified tool SAXParser:

Public abstract class SAXParser {protected String curqname;    protected StringBuilder Curvalue = new StringBuilder ();    protected SAXParser SAXParser;    protected String saxparserqname;    /** * required to generate the node name for sub-SAXParser */protected hashset<string> childparserqnames; Public SAXParser () {} public SAXParser (hashset<string> childparserqnames) {this.childparserqnames = c    Hildparserqnames; } protected void Startelement (String uri, String localname, String qName, Attributes Attributes) {if (QName = = N        ull) {return;        } if (SAXParser! = null) {saxparser.startelement (URI, QName, qName, attributes); }else if (childparserqnames! = null && childparserqnames.contains (qName)) {this.saxparser = Dispatchto (q            Name, attributes);                if (this.saxparser! = null) {this.saxparserqname = QName;            Saxparser.parserstart (attributes);        }}else{    Curqname = QName;            if (curvalue.length () > 0) {curvalue.delete (0, Curvalue.length ());            }}} protected void EndElement (String uri, String localname, String qName) {if (qName = = null) {        Return            } if (Qname.equals (saxparserqname)) {if (saxparser! = null) {saxparser.parserend ();            } saxparser = null;        Saxparserqname = null;        }else if (saxparser! = null) {saxparser.endelement (URI, QName, QName);            }else{parserelementend (QName, curvalue.tostring ());            Curqname = null;            if (curvalue.length () > 0) {curvalue.delete (0, Curvalue.length ());            }}} protected void characters (char[] ch, int start, int length) {if (saxparser! = null) {        Saxparser.characters (CH, start, length);            }else{String data = new String (ch, start, length); IF (data.length () > 0 && curqname! = null) {curvalue.append (data);  }}}/** * begins parsing an input stream * @param is file input stream * @param rootparserqname resolved file root node * @param rootparser                             Root parser */public static void Start (InputStream is, final String rootparserqname, Final SAXParser Rootparser) {try {saxparser parser = saxparserfactory.newinstance (            ). Newsaxparser ();  Parser.parse (IS, new DefaultHandler () {@Override public void startelement (string uri, string                        LocalName, String qName, Attributes Attributes) throws Saxexception {if (qName = = null) {                    Return } if (Rootparser! = null) {rootparser.startelement (URI, QName, qName, attributes)                    ; }else if (qname.equals (Rootparserqname)) {Rootparser.parsErstart (attributes);  }} @Override public void characters (char[] ch, int start, int length) throws saxexception {if (rootparser! = null) {rootparser.characters (ch, start, length)                    ; }} @Override public void EndElement (string uri, String localname, String qNa                    Me) throws Saxexception {if (qName = = null) {return;                            } if (Qname.contains (rootparserqname)) {if (Rootparser! = null) {                        Rootparser.parserend ();                    }}else if (rootparser! = null) {rootparser.endelement (URI, QName, QName);        }                }            });        } catch (Exception e) {e.printstacktrace ();     }    }/** * Node parsing begins */public abstract void Parserstart (Attributes Attributes);  /** * End of a child node resolution * @param value characters obtained values */public abstract void Parserelementend (String qName, String    Value); /** * Parsing events need to be passed down, returning the child SAXParser */public abstract SAXParser Dispatchto (String qName, Attributes Attributes) that need to be passed    ; /** * Node parsing end */public abstract void Parserend ();}

XML file Test.xml to parse:

<?xml version= "1.0" encoding= "UTF-8"? ><kml xmlns:gx= "http://www.google.com/kml/ext/2.2" >  < Document id= "123" >    <description>abc</description>    <author>csq</author>    <ExtendedData>      <data name= "TrackID" >        <value>293156</value>      </Data>      <data name= "Tracktypeid" >        <value>8</value>      </Data>    </extendeddata >    <Placemark>      <name> Shenzhen Bay Park </name>      <TimeStamp>        <when> 2015-03-21t10:00:13z</when>      </TimeStamp>      <Point>        <coordinates> 113.93946,22.48955,9.0</coordinates>      </Point>    </Placemark>  </Document> </kml>

　　　

Start parsing:

Root node kml, root node resolver kmlparser

Saxparser.start (Getassets (). Open ("TEST.KML"), "KML", New Kml.kmlparser (KML));

Partial node resolution implementation:

public static class Kmlparser extends SAXParser {        private kml kml;        Public Kmlparser (KML kml) {            super (new hashset<string> ());            THIS.KML = KML;            Childparserqnames.add ("Document");        }        @Override public void        Parserstart (Attributes Attributes) {        }        @Override public        void Parserelementend (String qName, String value) {        }        @Override public        saxparser Dispatchto (String qName, Attributes Attributes) {            if (qname.equals ("Document")) {                return new Document.documentparser (KML);            }            return null;        }        @Override public        void Parserend () {        }    }

　　

public static class Documentparser extends SAXParser {private KML kml;        Private document document;            Public Documentparser (KML KML) {super (New hashset<string> ());            THIS.KML = KML;            Childparserqnames.add ("Extendeddata");        Childparserqnames.add ("Placemark");            } @Override public void Parserstart (Attributes Attributes) {document = new document ();        Document.ID = Attributes.getvalue ("id");                } @Override public void Parserelementend (string qName, String value) {if (document = = NULL) {            Return            } if (Qname.equals ("description")) {document.description = value;            }else if (qname.equals ("author")) {document.author = value; }} @Override public SAXParser dispatchto (String qName, Attributes Attributes) {if (docume NT = = null) {return nUll            } if (Qname.equals ("Extendeddata")) {return new Extendeddata.extendeddataparser (document);            }else if (qname.equals ("Placemark")) {return new Placemark.placemarkparser (document);        } return null;        } @Override public void Parserend () {kml.document = document; }    }

public static class Placemarkparser extends SAXParser {private document document;        Private Placemark Placemark;            Public Placemarkparser (document document) {Super (new hashset<string> (1));            Childparserqnames.add ("point");        This.document = document;        } @Override public void Parserstart (Attributes Attributes) {placemark = new placemark ();                 } @Override public void Parserelementend (string qName, String value) {if (Qname.equals ("name")) {            Placemark.name = value;            }else if (qname.equals ("when")) {placemark.when = value; }} @Override public SAXParser dispatchto (String qName, Attributes Attributes) {if (qName.            Equals ("point")) {return new Point.pointparser (Placemark);        } return null; } @Override public void Parserend () {document.Placemark = Placemark; }    }

　　

public static class Extendeddataparser extends SAXParser {        private document document;        Private Extendeddata Extendeddata;        Public Extendeddataparser (document document) {            super (new hashset<string> (1));            Childparserqnames.add ("Data");            this.document = document;        }        @Override public        void Parserstart (Attributes Attributes) {            extendeddata = new Extendeddata ();        }        @Override public        void Parserelementend (String qName, String value) {        }        @Override public        SAXParser Dispatchto (String qName, Attributes Attributes) {            if (qname.equals ("Data")) {                return new Data.dataparser ( extendeddata);            }            return null;        }        @Override public        void Parserend () {            document.extendeddatas = extendeddata;        }    }

　　

......

Parsing results:

　　

Android simplifies XML sax parsing