"Android" Pa4d_ch6 using Internat Resources

1. In Android, the basic way to use network resources is as follows (synchronous)

   Try{URL URL=NewURL (myfeed); //Create A new HTTP URL connectionURLConnection connection =url.openconnection (); HttpURLConnection httpconnection=(httpurlconnection) connection; intResponsecode =Httpconnection.getresponsecode (); if(Responsecode = =HTTPURLCONNECTION.HTTP_OK) {InputStream in=Httpconnection.getinputstream ();      Processstream (in); }    }    Catch(malformedurlexception e) {log.d (TAG,"Malformed URL Exception.", E); }    Catch(IOException e) {log.d (TAG,"IO Exception.", E); }

2. At the same time, there are 3 main parsing XML in Android, including Dom parser, SAX parser and pull parser.
   1. Dom parser, Dombuilder, gets through documentbuilderfactory. These two classes are defined in the Javax package, and unlike J2SE, the latter has been rewritten in Android, directly acquiring the Apache Harmony implementation, and unfortunately, the Harmony project was abandoned by Apache in 2011.

       httpurlconnection httpconnection = int  responsecode = Httpconnection.getresponsecode ();  if  (Responsecode == HTTPCONNECTION.HTTP_OK) {InputStream in  = Httpconnection.getinputstream (); Documentbuilderfactory dbf  = Documentbuilderfactory. Newi    Nstance ();    Documentbuilder db  = Dbf.newdocumentbuilder ();     //  parse input     Document Dom = Db.parse (in); Element docele  = Dom.getdocumentelement ();}  

   3. SAX parser. Sax is a fast parsing and memory-intensive XML parser that is ideal for mobile devices such as Android. The Sax parsing XML file is event-driven, that is, it does not need to parse the entire document, and in the process of parsing the document in order of content, Sax determines whether the currently read character is a part of the valid XML syntax, and triggers the event if it conforms. The so-called events are actually some callback (callback) methods, which are defined in the ContentHandler interface.

      SAXParserFactory factory=saxparserfactory.newinstance ();  SAXParser parser=factory.newsaxparser ();  Myhandel Handel=new Myhandel ();  // here myhandle inherit from DefaulthandelParser.parse (InputStream, Handel);

   4. The
   5. pull parser. The following is the recommended use of this parser from Android Training,google
      Why should I learn the pull parser? Because pull parsing is looking for the desired tag in an XML document, pulling the required content into memory instead of pulling the entire document into memory, it is more suitable for small, mobile devices such as mobile phones with limited memory.

      We recommend Xmlpullparser , which is an efficient and maintainable a-to-parse XML on Android. Historically Android has had, implementations of this interface:

      • kxmlparser via Xm Lpullparserfactory.newpullparser () .
      • Expatpullparser , via xml.newpullparser () .

       factory =      Xmlpullparserfactory.newinstance (); Factory.setnamespaceaware ( true        = Factory.newpullparser ();