Android开发WeatherForecast程序

1，使用Googel API
http://www.google.com/ig/api?&weather=beijing

2，使用DOM解析XML

String weather = "";
String url = "[url=http://www.google.com/ig/api?&weather=beijing]http://www.google.com/ig/api?&weather=beijing[/url]";
 
DefaultHttpClient client = new DefaultHttpClient();
HttpUriRequest req = new HttpGet(url);
HttpResponse resp = client.execute(req);
HttpEntity ent = resp.getEntity();
 
InputStream stream = ent.getContent();
DocumentBuilder b = DocumentBuilderFactory.newInstance().newDocumentBuilder();
Document d = b.parse(new InputSource(stream)); 
NodeList n = d.getElementsByTagName("forecast_conditions");
for (int i = 0; i < n.getLength(); i++) {
 weather += n.item(i).getChildNodes().item(0).getAttributes().item(0).getNodeValue();
weather += ", ";
weather += (Integer.parseInt(n.item(i).getChildNodes().item(1).getAttributes().item(0).getNodeValue()) - 32) * 5 / 9; 
weather += " ~ ";
weather += (Integer.parseInt(n.item(i).getChildNodes().item(2).getAttributes().item(0).getNodeValue()) - 32) * 5 / 9;
weather += ", ";
 weather += n.item(i).getChildNodes().item(4).getAttributes().item(0).getNodeValue();
 weather += "\n";
}

3，另起Thread处理Web请求

new Thread() {
 
public void run() {
   try {
 
   // ...
   } catch (Exception e) {
    e.printStackTrace();
   }
 }
 
}.start();
 

4，使用Handler传递Thread处理结果到UI主Thread

h = new Handler() {
public void handleMessage(Message msg) {
  tv.setText((String)msg.obj);
}
};
 
new Thread() {
// ...
Message msg = h.obtainMessage(1, 1, 1, weather);
h.sendMessage(msg);
}

5，完整代码

package com.hideto.weatherforecast;
 
import java.io.InputStream;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpUriRequest;
import org.apache.http.impl.client.DefaultHttpClient;
import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.widget.TextView;
 
public class WeatherForecast extends Activity {
public TextView tv;
public Handler h;
 
@Override 
public void onCreate(Bundle savedInstanceState) {
 
  super.onCreate(savedInstanceState);
  tv = new TextView(this);
  tv.setText("Loading...");
  setContentView(tv);
  h = new Handler() {
   public void handleMessage(Message msg) {
    tv.setText((String)msg.obj);
   }
  };
  new Thread() {
   public void run() {
    try {

     String weather = "";
     String url = "[url=http://www.google.com/ig/api?&weather=beijing]http://www.google.com/ig/api?&weather=beijing[/url]";
     DefaultHttpClient client = new DefaultHttpClient();
     HttpUriRequest req = new HttpGet(url);
     HttpResponse resp = client.execute(req);
     HttpEntity ent = resp.getEntity();
     InputStream stream = ent.getContent();
     DocumentBuilder b = DocumentBuilderFactory.newInstance().newDocumentBuilder();
     Document d = b.parse(new InputSource(stream));
     NodeList n = d.getElementsByTagName("forecast_conditions");

     for (int i = 0; i < n.getLength(); i++) {
      weather += n.item(i).getChildNodes().item(0).getAttributes().item(0).getNodeValue();
      weather += ", ";
      weather += (Integer.parseInt(n.item(i).getChildNodes().item(1).getAttributes().item(0).getNodeValue()) - 32) * 5 / 9;
　　　 weather += " ~ ";
      weather += (Integer.parseInt(n.item(i).getChildNodes().item(2).getAttributes().item(0).getNodeValue()) - 32) * 5 / 9;
 　　  weather += ", ";
      weather += n.item(i).getChildNodes().item(4).getAttributes().item(0).getNodeValue();
      weather += "\n";
     }
     Message msg = h.obtainMessage(1, 1, 1, weather);
     h.sendMessage(msg);
    } catch (Exception e) {
     e.printStackTrace();
    }
   }
  }.start();

}
 
}

6，修改AndroidManifest.xml加上INTERNET访问权限

<?xml version="1.0" encoding="utf-8"?>
 
<manifest xmlns:android="[url=http://schemas.android.com/apk/res/android]http://schemas.android.com/apk/res/android[/url]"
       package="com.hideto.weatherforecast"
       android:versionCode="1"
       android:versionName="1.0.0">
     <uses-permission android:name="android.permission.INTERNET"></uses-permission>
     <application android:icon="@drawable/icon" android:label="@string/app_name">
         <activity android:name=".WeatherForecast"
                   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>