Android-Earthquake(地震显示器)项目详解
Earthquake(地震显示器) 项目 详解
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本文地址: http://blog.csdn.net/caroline_wendy/article/details/21976997
环境: Android Studio 0.5.2, Gradle 1.11, kindle fire
时间: 2014-3-24
Earthquake项目, 主要是读取USGS(United States Geological Survey, 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: http://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/2.5_day.atom
格式:
<feed xmlns="http://www.w3.org/2005/Atom" xmlns:georss="http://www.georss.org/georss"> <title>USGS Magnitude 2.5+ Earthquakes, Past Day</title> <updated>2014-03-24T07:56:39Z</updated> <author> <name>U.S. Geological Survey</name> <uri>http://earthquake.usgs.gov/</uri> </author> <id> http://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/2.5_day.atom </id> <link rel="self" href="http://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/2.5_day.atom"/> <icon>http://earthquake.usgs.gov/favicon.ico</icon> <entry> <id>urn:earthquake-usgs-gov:ci:15479569</id> <title>M 2.9 - 9km W of Alberto Oviedo Mota, Mexico</title> <updated>2014-03-24T07:48:34.609Z</updated> <link rel="alternate" type="text/html" href="http://earthquake.usgs.gov/earthquakes/eventpage/ci15479569"/> <summary type="html"> <![CDATA[ <p class="quicksummary"><a href="http://earthquake.usgs.gov/earthquakes/eventpage/ci15479569#dyfi" class="mmi-I" title="Did You Feel It? maximum reported intensity (0 reports)">DYFI? - <strong class="roman">I</strong></a></p><dl><dt>Time</dt><dd>2014-03-24 07:38:10 UTC</dd><dd>2014-03-23 23:38:10 -08:00 at epicenter</dd><dt>Location</dt><dd>32.222°N 115.274°W</dd><dt>Depth</dt><dd>14.10 km (8.76 mi)</dd></dl> ]]> </summary> <georss:point>32.2215 -115.274</georss:point> <georss:elev>-14100</georss:elev> <category label="Age" term="Past Hour"/> <category label="Magnitude" term="Magnitude 2"/> </entry> ...... ......
Earthquake的具体设计:
新建项目: Earthquake
1. 新建Quake(Quake.java)类, 显示地震数据.
位置: java->package->Quake
package mzx.spike.earthquake.app; import android.location.Location; import java.text.SimpleDateFormat; import java.util.Date; public class Quake { private Date date; private String details; private Location location; private double magnitude; private String link; public Date getDate() { return date; } public String getDetails() { return details; } public Location getLocation() { return location; } public double getMagnitude() { return magnitude; } public String getLink() { return link; } public Quake(Date _d, String _det, Location _loc, double _mag, String _link) { date = _d; details = _det; location = _loc; magnitude = _mag; link = _link; } @Override public String toString() { SimpleDateFormat sdf = new SimpleDateFormat("HH.mm"); String dateString = sdf.format(date); return dateString + ": " + magnitude + " " + details; } }详解:
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;
2. 修改activity_main.xml, 添加fragment.
位置: res->layout->activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/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"> <fragment android:name="mzx.spike.earthquake.app.EarthquakeListFragment" android:id="@+id/EarthquakeListFragment" android:layout_width="match_parent" android:layout_height="match_parent" /> </RelativeLayout>
添加Fragment, 指定实现(.java)文件位置.
3. 新建EarthquakeListFragment.java
位置: java->package->EarthquakeListFragment.java
package mzx.spike.earthquake.app; import android.app.ListFragment; import android.location.Location; import android.os.Bundle; import android.os.Handler; import android.util.Log; import android.widget.ArrayAdapter; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.NodeList; import org.xml.sax.SAXException; import java.io.IOException; import java.io.InputStream; import java.net.HttpURLConnection; import java.net.MalformedURLException; import java.net.URL; import java.net.URLConnection; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.ArrayList; import java.util.Date; import java.util.GregorianCalendar; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.ParserConfigurationException; public class EarthquakeListFragment extends ListFragment { ArrayAdapter<Quake> aa; ArrayList<Quake> earthquakes = new ArrayList<Quake>(); @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); int layoutID = android.R.layout.simple_list_item_1; aa = new ArrayAdapter<Quake>(getActivity(), layoutID , earthquakes); setListAdapter(aa); Thread t = new Thread(new Runnable() { @Override public void run() { refreshEarthquakes(); } }); t.start(); } private static final String TAG = "EARTHQUAKE"; private Handler handler = new Handler(); private void refreshEarthquakes() { // Get the XML URL url; try { String quakeFeed = getString(R.string.quake_feed); url = new URL(quakeFeed); URLConnection connection; connection = url.openConnection(); HttpURLConnection httpConnection = (HttpURLConnection)connection; int responseCode = httpConnection.getResponseCode(); if (responseCode == HttpURLConnection.HTTP_OK) { InputStream in = httpConnection.getInputStream(); DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); DocumentBuilder db = dbf.newDocumentBuilder(); // Parse the earthquake feed. Document dom = db.parse(in); Element docEle = dom.getDocumentElement(); // Clear the old earthquakes earthquakes.clear(); // Get a list of each earthquake entry. NodeList nl = docEle.getElementsByTagName("entry"); if (nl != null && nl.getLength() > 0) { for (int i = 0 ; i < nl.getLength(); i++) { Element entry = (Element)nl.item(i); Element title = (Element)entry.getElementsByTagName("title").item(0); Element g = (Element)entry.getElementsByTagName("georss:point").item(0); Element when = (Element)entry.getElementsByTagName("updated").item(0); Element link = (Element)entry.getElementsByTagName("link").item(0); String details = title.getFirstChild().getNodeValue(); String hostname = "http://earthquake.usgs.gov"; String linkString = hostname + link.getAttribute("href"); String point = g.getFirstChild().getNodeValue(); String dt = when.getFirstChild().getNodeValue(); SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'hh:mm:ss.SSS'Z'"); Date qdate = new GregorianCalendar(0,0,0).getTime(); try { qdate = sdf.parse(dt); } catch (ParseException e) { Log.d(TAG, "Date parsing exception.", e); } String[] location = point.split(" "); Location l = new Location("dummyGPS"); l.setLatitude(Double.parseDouble(location[0])); l.setLongitude(Double.parseDouble(location[1])); String magnitudeString = details.split(" ")[1]; int end = magnitudeString.length()-1; double magnitude = Double.parseDouble(magnitudeString.substring(0, end)); details = details.split(",")[1].trim(); final Quake quake = new Quake(qdate, details, l, magnitude, linkString); // Process a newly found earthquake handler.post(new Runnable() { @Override public void run() { addNewQuake(quake); } }); } } } } catch (MalformedURLException e) { Log.d(TAG, "MalformedURLException", e); } catch (IOException e) { Log.d(TAG, "IOException", e); } catch (ParserConfigurationException e) { Log.d(TAG, "Parser Configuration Exception", e); } catch (SAXException e) { Log.d(TAG, "SAX Exception", e); } finally { } } private void addNewQuake(Quake _quake) { // Add the new quake to our list of earthquakes. earthquakes.add(_quake); // Notify the array adapter of a change. aa.notifyDataSetChanged(); } }详解:
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(network call)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.
4. 修改strings信息
位置: res->values->strings
<?xml version="1.0" encoding="utf-8"?> <resources> <string name="app_name">Earthquake</string> <string name="hello_world">Hello world!</string> <string name="action_settings">Settings</string> <string name="quake_feed">http://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/2.5_day.atom</string> </resources>
添加相应的订阅源(feeds).
5. 修改AndroidManifest.xml
位置: root->AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="mzx.spike.earthquake.app" > <uses-permission android:name="android.permission.INTERNET"/> <application android:allowBackup="true" android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" > <activity android:name="mzx.spike.earthquake.app.MainActivity" android:label="@string/app_name" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>
提供网络访问权限(permission), <uses-permission android:name="android.permission.INTERNET"/>.
6. 运行程序.
下载地址: http://download.csdn.net/detail/u012515223/7091879
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