【移动应用开发技术】Android - Earthquake(地震显示器) 项目 详解

【移动应用开发技术】Android-Earthquake(地震显示器)项目详解

Earthquake(地震显示器)项目详解本文地址:

/caroline_wendy/article/details/21976997环境:AndroidStudio0.5.2,Gradle1.11,kindlefire时间:2014-3-24Earthquake项目,主要是读取USGS(UnitedStatesGeologicalSurvey,美国地址勘探局)提供的feeds(订阅源),进行显示数据;需要读取互联网的数据,进行格式解析(parse),数据类型是atom类型,类似XML.订阅源地址:

/earthquakes/feed/v1.0/summary/2.5_day.atom格式:<feedxmlns="/2005/Atom"xmlns:georss="/georss"><title>USGSMagnitude2.5+Earthquakes,PastDay</title><updated>2014-03-24T07:56:39Z</updated><author><name>U.S.GeologicalSurvey</name><uri>/</uri></author><id>/earthquakes/feed/v1.0/summary/2.5_day.atom</id><linkrel="self"href="/earthquakes/feed/v1.0/summary/2.5_day.atom"/><icon>/favicon.ico</icon><entry><id>urn:earthquake-usgs-gov:ci:15479569</id><title>M2.9-9kmWofAlbertoOviedoMota,Mexico</title><updated>2014-03-24T07:48:34.609Z</updated><linkrel="alternate"type="text/html"href="/earthquakes/eventpage/ci15479569"/><summarytype="html"><![CDATA[<pclass="quicksummary"><ahref="/earthquakes/eventpage/ci15479569#dyfi"class="mmi-I"title="DidYouFeelIt?maximumreportedintensity(0reports)">DYFI?-<strongclass="roman">I</strong></a></p><dl><dt>Time</dt><dd>2014-03-2407:38:10UTC</dd><dd>2014-03-2323:38:10-08:00atepicenter</dd><dt>Location</dt><dd>32.222°N115.274°W</dd><dt>Depth</dt><dd>14.10km(8.76mi)</dd></dl>]]></summary><georss:point>32.2215-115.274</georss:point><georss:elev>-14100</georss:elev><categorylabel="Age"term="PastHour"/><categorylabel="Magnitude"term="Magnitude2"/></entry>新建项目:Earthquake位置:java->package->Quakepackagemzx.spike.earthquake.app;importandroid.location.Location;importjava.text.SimpleDateFormat;importjava.util.Date;publicclassQuake{privateDatedate;privateStringdetails;privateLocationlocation;privatedoublemagnitude;privateStringlink;publicDategetDate(){returndate;}publicStringgetDetails(){returndetails;}publicLocationgetLocation(){returnlocation;}publicdoublegetMagnitude(){returnmagnitude;}publicStringgetLink(){returnlink;}publicQuake(Date_d,String_det,Location_loc,double_mag,String_link){date=_d;details=_det;location=_loc;magnitude=_mag;link=_link;}@OverridepublicStringtoString(){SimpleDateFormatsdf=newSimpleDateFormat("HH.mm");StringdateString=sdf.format(date);returndateString+":"+magnitude+""+details;}}1.显示的类型:date,日期;details,详细信息,地点;location,位置;magnitude,震级;link,链接;2.get()方法,返回信息;构造函数,赋初值;toString(),默认输出信息;位置:res->layout->activity_main.xml<RelativeLayoutxmlns:android="/apk/res/android"xmlns:tools="/tools"android:layout_width="match_parent"android:layout_height="match_parent"android:paddingLeft="@dimen/activity_horizontal_margin"android:paddingRight="@dimen/activity_horizontal_margin"android:paddingTop="@dimen/activity_vertical_margin"android:paddingBottom="@dimen/activity_vertical_margin"tools:context="mzx.spike.earthquake.app.MainActivity"><fragmentandroid:name="mzx.spike.earthquake.app.EarthquakeListFragment"android:id="@+id/EarthquakeListFragment"android:layout_width="match_parent"android:layout_height="match_parent"/></RelativeLayout>位置:java->package->EarthquakeListFragment.javapackagemzx.spike.earthquake.app;importandroid.app.ListFragment;importandroid.location.Location;importandroid.os.Bundle;importandroid.os.Handler;importandroid.util.Log;importandroid.widget.ArrayAdapter;importorg.w3c.dom.Document;importorg.w3c.dom.Element;importorg.w3c.dom.NodeList;importorg.xml.sax.SAXException;importjava.io.IOException;importjava.io.InputStream;import.HttpURLConnection;import.MalformedURLException;import.URL;import.URLConnection;importjava.text.ParseException;importjava.text.SimpleDateFormat;importjava.util.ArrayList;importjava.util.Date;importjava.util.GregorianCalendar;importjavax.xml.parsers.DocumentBuilder;importjavax.xml.parsers.DocumentBuilderFactory;importjavax.xml.parsers.ParserConfigurationException;publicclassEarthquakeListFragmentextendsListFragment{ArrayAdapter<Quake>aa;ArrayList<Quake>earthquakes=newArrayList<Quake>();@OverridepublicvoidonActivityCreated(BundlesavedInstanceState){super.onActivityCreated(savedInstanceState);intlayoutID=android.R.layout.simple_list_item_1;aa=newArrayAdapter<Quake>(getActivity(),layoutID,earthquakes);setListAdapter(aa);Threadt=newThread(newRunnable(){@Overridepublicvoidrun(){refreshEarthquakes();}});t.start();}privatestaticfinalStringTAG="EARTHQUAKE";privateHandlerhandler=newHandler();privatevoidrefreshEarthquakes(){//GettheXMLURLurl;try{StringquakeFeed=getString(R.string.quake_feed);url=newURL(quakeFeed);URLConnectionconnection;connection=url.openConnection();HttpURLConnectionhttpConnection=(HttpURLConnection)connection;intresponseCode=httpConnection.getResponseCode();if(responseCode==HttpURLConnection.HTTP_OK){InputStreamin=httpConnection.getInputStream();DocumentBuilderFactorydbf=DocumentBuilderFactory.newInstance();DocumentBuilderdb=dbf.newDocumentBuilder();//Parsetheearthquakefeed.Documentdom=db.parse(in);ElementdocEle=dom.getDocumentElement();//Cleartheoldearthquakesearthquakes.clear();//Getalistofeachearthquakeentry.NodeListnl=docEle.getElementsByTagName("entry");if(nl!=null&&nl.getLength()>0){for(inti=0;i<nl.getLength();i++){Elemententry=(Element)nl.item(i);Elementtitle=(Element)entry.getElementsByTagName("title").item(0);Elementg=(Element)entry.getElementsByTagName("georss:point").item(0);Elementwhen=(Element)entry.getElementsByTagName("updated").item(0);Elementlink=(Element)entry.getElementsByTagName("link").item(0);Stringdetails=title.getFirstChild().getNodeValue();Stringhostname="";StringlinkString=hostname+link.getAttribute("href");Stringpoint=g.getFirstChild().getNodeValue();Stringdt=when.getFirstChild().getNodeValue();SimpleDateFormatsdf=newSimpleDateFormat("yyyy-MM-dd'T'hh:mm:ss.SSS'Z'");Dateqdate=newGregorianCalendar(0,0,0).getTime();try{qdate=sdf.parse(dt);}catch(ParseExceptione){Log.d(TAG,"Dateparsingexception.",e);}String[]location=point.split("");Locationl=newLocation("dummyGPS");l.setLatitude(Double.parseDouble(location[0]));l.setLongitude(Double.parseDouble(location[1]));StringmagnitudeString=details.split("")[1];intend=magnitudeString.length()-1;doublemagnitude=Double.parseDouble(magnitudeString.substring(0,end));details=details.split(",")[1].trim();finalQuakequake=newQuake(qdate,details,l,magnitude,linkString);//Processanewlyfoundearthquakehandler.post(newRunnable(){@Overridepublicvoidrun(){addNewQuake(quake);}});}}}}catch(MalformedURLExceptione){Log.d(TAG,"MalformedURLException",e);}catch(IOExceptione){Log.d(TAG,"IOException",e);}catch(ParserConfigurationExceptione){Log.d(TAG,"ParserConfigurationException",e);}catch(SAXExceptione){Log.d(TAG,"SAXException",e);}finally{}}privatevoidaddNewQuake(Quake_quake){//Addthenewquaketoourlistofearthquakes.earthquakes.add(_quake);//Notifythearrayadapterofachange.aa.notifyDataSetChanged();}}1.重写onActivityCreated()方法,绑定适配器,在线程(thread)中刷新地震信息(refreshEarthquakes);2.刷新地震信息refreshEarthquakes()方法,根据订阅源(feed),创建HTTP链接;3.解析文档(parse),清空数据(clear);4.解析atom格式的标签,根据标签属性,输出相应的信息;5.实例化(new)Quake类,在handler(句柄)中,运行添加地震信息的方法(addNewQuake);6.注意链接需要相应的异常捕获(catch)方式,否则报错;7.网络调用(networkcall)在主Activity调用,会报错,需要在线程,后台(asynctask)运行;8.Handler会产生歧义,注意使用Android的相应类,不是java的,否则无法实例化(initialized)9.日期格式(SimpleDateFormat)解析,需要匹配相应的字符串,否则抛出异常,无法解析(parse);10添加新的地震信息(addNewQuake),通知适配器(notifyDataSetChanged),进行改变.位置:res->values->strings<?xmlversion="1.0"encoding="utf-8"?><resources>