MainActivity调用 DataCall.getJSON方法，然后触发AsyncTask。但是我不确定如何将数据返回到原始的Activity。如何从AsyncTask中获取数据?
MainActivity调用 DataCall,应该返回一个字符串并将其保存在state_data。
String state_data = DataCall.getJSON(spinnerURL,spinnerContentType);
DataCall:
public class DataCall extends Activity {
private static final String TAG = "MyApp";
private class DownloadWebPageTask extends AsyncTask<String, Void, String> {
protected String doInBackground(String... urls) {
String response = "";
for (String url : urls) {
DefaultHttpClient client = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(url);
try {
HttpResponse execute = client.execute(httpGet);
InputStream content = execute.getEntity().getContent();
BufferedReader buffer = new BufferedReader(
new InputStreamReader(content));
String s = "";
while ((s = buffer.readLine()) != null) {
response += s;
}
} catch (Exception e) {
e.printStackTrace();
}
}
return response;
}
protected void onPostExecute(String result) {
//THIS IS WHERE I NEED TO RETURN MY DATA TO THE MAIN ACTIVITY. (I am guessing)
}
}
public void getJSON(String myUrlString, String contentType) {
DownloadWebPageTask task = new DownloadWebPageTask();
task.execute(new String[] { "http://www.mywebsite.com/" + myUrlString });
}
}
修改AsyncTask：
public class GetData extends AsyncTask<String, Void, String>
{
DataDownloadListener dataDownloadListener;
public GetData()
{
}
public void setDataDownloadListener(DataDownloadListener dataDownloadListener) {
this.dataDownloadListener = dataDownloadListener;
}
@Override
protected Object doInBackground(Object... param)
{
return null;
}
@Override
protected void onPostExecute(Object results)
{
if(results != null)
{
dataDownloadListener.dataDownloadedSuccessfully(results);
}
else
dataDownloadListener.dataDownloadFailed();
}
public static interface DataDownloadListener {
void dataDownloadedSuccessfully(Object data);
void dataDownloadFailed();
}
}
在Activity中使用：
GetData getdata = new GetData();
getdata.setDataDownloadListener(new DataDownloadListener()
{
@SuppressWarnings("unchecked")
@Override
public void dataDownloadedSuccessfully(Object data) {
}
@Override
public void dataDownloadFailed() {
}
});
getdata.execute("");