我一直在开发一个简单的天气应用程序 - 我正在使用谷歌天气API。我正在尝试下载 XML 文件并根据其中的信息构建 UI。
我尝试使用 AsyncTask 下载 XML 文件，然后解析它 - 但有些东西不起作用！当我运行代码时，我没有任何错误/应用程序启动，但 xml 文件中的信息未显示！
代码如下：
package com.android.weatherApp;
public class WeatherAppActivity extends Activity {
static String url="http://www.google.com/ig/api?weather=";
static final String KEY_FORCAST_INFO="forcast_information";
static final String KEY_CITY="city";
static final String KEY_CURRENT_CONDITIONS="current_conditions";
static final String KEY_CONDITION="condition";
static final String KEY_TEMP="temp_c";
static final String KEY_ICON_SRC="icon";
static final String KEY_FORCAST_COND="forecast_conditions";
static final String KEY_DAY_WEEK="day_of_week";
static final String KEY_LOW_TEMP="low";
static final String KEY_HIGH_TEMP="high";
Document finalDoc;
XMLParser xmlParser;
private TextView currentWeather;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
downloadXMLFile task=new downloadXMLFile();
task.execute("New+York");
}
private class downloadXMLFile extends AsyncTask<String,Void,String>
{
@Override
protected String doInBackground(String... params) {
String xml=null;
try{
DefaultHttpClient httpClient=new DefaultHttpClient();
HttpPost httpPost=new HttpPost(url+params[0]);
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity=httpResponse.getEntity();
xml=EntityUtils.toString(httpEntity);
}
catch(UnsupportedEncodingException e)
{
e.printStackTrace();
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return xml;
}
@Override
protected void onPostExecute(String xmlString)
{
Document doc = null;
DocumentBuilderFactory dbf= DocumentBuilderFactory.newInstance();
try {
DocumentBuilder db = dbf.newDocumentBuilder();
InputSource is=new InputSource();
is.setCharacterStream(new StringReader(xmlString));
doc=db.parse(is);
} catch (ParserConfigurationException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SAXException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
finalDoc=doc;
NodeList nl=finalDoc.getElementsByTagName(KEY_CURRENT_CONDITIONS);
NodeList nl2=finalDoc.getElementsByTagName(KEY_FORCAST_COND);
currentWeather=(TextView)findViewById(R.id.currentState);
TextView currentTemp = (TextView)findViewById(R.id.tempC);
TextView currentLocation=(TextView)findViewById(R.id.currentLocation);
currentLocation.setText("Iasi");
for(int i=0;i<nl.getLength();i++)
{
Element e= (Element)nl.item(i);
String cs=xmlParser.getValue(e, KEY_CONDITION).toUpperCase();
currentWeather.setText(cs);
String temperature=xmlParser.getValue(e, KEY_TEMP);
currentTemp.setText(temperature);
String logoImg=xmlParser.getValue(e, KEY_ICON_SRC).toLowerCase();
if(logoImg.equals("/ig/images/weather/sunny.gif"))
{
ImageView img=(ImageView)findViewById(R.id.wImg);
img.setImageResource(R.drawable.sun);
}
}
for(int i=0;i<nl2.getLength();i++)
{
Element e=(Element)nl2.item(i);
TextView day1=(TextView)findViewById(R.id.day1);
day1.setText("TOMORW");
TextView day2=(TextView)findViewById(R.id.day2);
TextView day3=(TextView)findViewById(R.id.day3);
ImageView img1=(ImageView)findViewById(R.id.day1Logo);
ImageView img2=(ImageView)findViewById(R.id.day2Logo);
ImageView img3=(ImageView)findViewById(R.id.day3Logo);
TextView highTemp1=(TextView)findViewById(R.id.day1MaxTemp);
TextView highTemp2=(TextView)findViewById(R.id.day2MaxTemp);
TextView highTemp3=(TextView)findViewById(R.id.day3MaxTemp);
String d1=xmlParser.getValue(e, KEY_DAY_WEEK).toUpperCase();
String t=xmlParser.getValue(e, KEY_HIGH_TEMP); //get the max value of temperature - Fahrenheit
int tempF=Integer.parseInt(t); // make the string a number
float tC=(float) ((5./9)*(tempF-32)); // calculate the Celsius value of temperature
tempF=(int)tC; // get only the Int value
t=Integer.toString(tempF); // transform the temperature value back to string
switch(i)
{
case 1:
highTemp1.setText(t);
break;
case 2:
highTemp2.setText(t);
day2.setText(d1);
break;
case 3:
highTemp3.setText(t);
day3.setText(d1);
break;
}
}
}
}
请你告诉我我做错了什么。谢谢！
首先，您的 url 变量包含"http://www.google.com/ig/api?weather="而不是"http://www.google.com/ig/api?weather=New+York"，因此 xml 内容为空。
在doInBackground方法中尝试这样的事情：
String currentUrl = url;
if(params.length>0 && params[0]!=null)currentUrl+= params[0];
我看到您在循环中实例化了视图。必须在 onCreate 方法或 onStart 方法中实例化它们。这样，您将在创建活动后实例化这些变量，您将获得性能。
在您的清单中，您是否添加了<uses-permission android:name="android.permission.INTERNET"/>？
你能把Log.i("test",xmlString);放在你的 onPostExecute 中并在你的日志中查看结果吗？