Piglet's Android starter Road Day 8 Part 1

Piglet's Android starter Road Day 8 Part 1

Analysis of--xml file in Android network programming

---reprint please specify the Source: Coder-pig

Introduction to this section:

Unknowingly, this series of blog has been written to the 8th day, many friends feedback benefited a lot, to help you

I feel gratified, originally Day 8 is want to analyze the graphics and image processing of Android, but I want to go,

Or decided to first explain the network programming in Android, because a friend proposed to explain the network, so

In Day 8 we will analyze some of the applications of Android in the Web, and this blog is for beginners,

And in view of the author's level, so just analysis, not in-depth! In Day 8 We will explain some of the basic

Web applications, such as downloading data on the network, images, file Xml,json, building simple client-side and service-to-end intersection

Mutual wait! In Part 1 we will explain in detail the common methods of XML and parsing XML!

Learning Roadmap for this section:

The text of this section:

three ways Android interacts with the Internet:

An introduction to the XML file highlights:

comparison of common methods for parsing XML in Android:

Sax Parsing xml file:

The process of Sax parsing xml

Core code:

①saxservice.java:

Package Com.jay.example.service;import Java.util.arraylist;import Org.xml.sax.attributes;import Org.xml.sax.saxexception;import Org.xml.sax.helpers.defaulthandler;import Android.util.log;import Com.jay.example.bean.person;public class Saxservice extends defaulthandler{private person person;private ArrayList <Person> persons;//The element tag that is currently parsed private String TagName = null;//is triggered when read to the start of a document, and is typically done here with some initialization @overridepublic void Startdocument () throws saxexception {this.persons = new arraylist<person> (); LOG.I ("SAX", "read to document header, start parsing xml");} Called when a start tag is read, the second parameter is the signature, the last parameter is an array of attributes @overridepublic void startelement (String uri, String localname, String qName, Attributes Attributes) throws Saxexception {if (localname.equals ("person")} {person = new person ();p Erson.setid ( Integer.parseint (Attributes.getvalue ("id"))); LOG.I ("SAX", "read Tags");} This.tagname = LocalName;} The processing XML file reads to the content, the first parameter is the string content, followed by the starting position and length @overridepublic void characters (char[] ch, int start, int length) throws saxexception {//determines if the current label is valid if (This.tagName = null) {String data = new String (ch,start,length);//reads the contents of the label if (This.tagName.equals ("name")) { This.person.setName (data);} else if (this.tagName.equals ("Age")) {This.person.setAge (Integer.parseint (data));}} The end of the document section, where the object is added to the binding @overridepublic void EndElement (String uri, String localname, String qName) throws Saxexception {if ( Localname.equals ("person")) {This.persons.add (person);p Erson = null;} This.tagname = null;} Get persons Collection Public arraylist<person> Getpersons () {return persons;}}

the ReadXml () method in ②mainactivity:

Private Arraylist<person> ReadXml () throws exception{//gets the file resource to establish an input stream object InputStream is = Getassets (). Open (" Persons.xml ")//① create XML parsing processor Saxservice SS = new Saxservice ();//② get sax parsing factory SAXParserFactory factory = Saxparserfactory.newinstance ();//③ creates a sax parser saxparser parser = Factory.newsaxparser ();//④ assigns the XML parsing processor to the parser, parses the document, Send event to Processor Parser.parse (IS,SS); Is.close (); return ss.getpersons ();}

DOM parsing xml file

The flow of DOM parsing xml

Core code:

The DOM parses the XML code:

public static arraylist<person> Queryxml (context context) {arraylist<person> Persons = new arraylist< Person> (); try {//① get DOM Parser Factory Example: documentbuilderfactory dbfactory = Documentbuilderfactory.newinstance ();// ② gets the DOM parser from the DOM factory Documentbuilder Dbbuilder = Dbfactory.newdocumentbuilder ();//③ reads the XML file to parse into the DOM parser document DOC = Dbbuilder.parse (Context.getassets (). Open ("Persons2.xml")); System.out.println ("Domimplemention object to process the document =" + doc.getimplementation ());//④ gets the list of nodes for the element named person in the document nodelist NList = Doc.getelementsbytagname ("person");//⑤ iterates through the collection, displaying the elements in the collection and the names of the child elements for (int i = 0;i < Nlist.getlength (); i++) {// The element personelement = (Element) Nlist.item (i) is first parsed from the person elements. Person p = new person ();p. SetId (integer.valueof (Personelement.getattribute ("id")));// Gets the note collection for name and age under person nodelist childnolist = Personelement.getchildnodes (); for (int j = 0;j < Childnolist.getlength (); j + +) {Node Childnode = Childnolist.item (j);//Determines whether the child note type is an element NoteIf (childnode.getnodetype () = = Node.element_node) {ElemeNT Childelement = (Element) childnode;if ("Name". Equals (Childelement.getnodename ())) P.setname ( Childelement.getfirstchild (). Getnodevalue ()); else if ("Age". Equals (Childelement.getnodename ())) P.setage ( Integer.valueof (Childelement.getfirstchild (). Getnodevalue ()));}} Persons.add (P);}} catch (Exception e) {e.printstacktrace ();} return Persons;}

parsing an XML file using the Pull parser

Using code Examples:

To facilitate the presentation, three parsing methods are packaged into one program:

Parse the XML file in three different ways, and generate an XML file using the pull parser, in the data/data/< package name >/file Directory

The generated XML file can be found

:

Reference code: code Download

Piglet's Android starter Road Day 8 Part 1