我有两门课。我的主活动和一个扩展AsyncTask，现在在我的主活动中，我需要从AsyncTask中的OnPostExecute()获得结果。如何将结果传递给我的主活动?
下面是示例代码。
我的主要活动。
public class MainActivity extends Activity{
AasyncTask asyncTask = new AasyncTask();
@Override
public void onCreate(Bundle aBundle) {
super.onCreate(aBundle);
//Calling the AsyncTask class to start to execute.
asyncTask.execute(a.targetServer);
//Creating a TextView.
TextView displayUI = asyncTask.dataDisplay;
displayUI = new TextView(this);
this.setContentView(tTextView);
}
}
这是AsyncTask类
public class AasyncTask extends AsyncTask<String, Void, String> {
TextView dataDisplay; //store the data
String soapAction = "http://sample.com"; //SOAPAction header line.
String targetServer = "https://sampletargeturl.com"; //Target Server.
//SOAP Request.
String soapRequest = "<sample XML request>";
@Override
protected String doInBackground(String... string) {
String responseStorage = null; //storage of the response
try {
//Uses URL and HttpURLConnection for server connection.
URL targetURL = new URL(targetServer);
HttpURLConnection httpCon = (HttpURLConnection) targetURL.openConnection();
httpCon.setDoOutput(true);
httpCon.setDoInput(true);
httpCon.setUseCaches(false);
httpCon.setChunkedStreamingMode(0);
//properties of SOAPAction header
httpCon.addRequestProperty("SOAPAction", soapAction);
httpCon.addRequestProperty("Content-Type", "text/xml; charset=utf-8");
httpCon.addRequestProperty("Content-Length", "" + soapRequest.length());
httpCon.setRequestMethod(HttpPost.METHOD_NAME);
//sending request to the server.
OutputStream outputStream = httpCon.getOutputStream();
Writer writer = new OutputStreamWriter(outputStream);
writer.write(soapRequest);
writer.flush();
writer.close();
//getting the response from the server
InputStream inputStream = httpCon.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
ByteArrayBuffer byteArrayBuffer = new ByteArrayBuffer(50);
int intResponse = httpCon.getResponseCode();
while ((intResponse = bufferedReader.read()) != -1) {
byteArrayBuffer.append(intResponse);
}
responseStorage = new String(byteArrayBuffer.toByteArray());
} catch (Exception aException) {
responseStorage = aException.getMessage();
}
return responseStorage;
}
protected void onPostExecute(String result) {
aTextView.setText(result);
}
}
我觉得下面的方法很简单。
我已经声明了一个回调接口
public interface AsyncResponse {
void processFinish(Object output);
}
然后创建异步任务来响应所有类型的并行请求
public class MyAsyncTask extends AsyncTask<Object, Object, Object> {
public AsyncResponse delegate = null;//Call back interface
public MyAsyncTask(AsyncResponse asyncResponse) {
delegate = asyncResponse;//Assigning call back interfacethrough constructor
}
@Override
protected Object doInBackground(Object... params) {
//My Background tasks are written here
return {resutl Object}
}
@Override
protected void onPostExecute(Object result) {
delegate.processFinish(result);
}
}
然后在活动类中单击按钮时调用异步任务。
public class MainActivity extends Activity{
@Override
public void onCreate(Bundle savedInstanceState) {
Button mbtnPress = (Button) findViewById(R.id.btnPress);
mbtnPress.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
MyAsyncTask asyncTask =new MyAsyncTask(new AsyncResponse() {
@Override
public void processFinish(Object output) {
Log.d("Response From Asynchronous task:", (String) output);
mbtnPress.setText((String) output);
}
});
asyncTask.execute(new Object[] { "Your request to aynchronous task class is giving here.." });
}
});
}
}
谢谢
试试这个:
public class SomAsyncTask extends AsyncTask<String, Integer, JSONObject> {
private CallBack callBack;
public interface CallBack {
void async( JSONObject jsonResult );
void sync( JSONObject jsonResult );
void progress( Integer... status );
void cancel();
}
public SomAsyncTask(CallBack callBack) {
this.callBack = callBack;
}
@Override
protected JSONObject doInBackground(String... strings) {
JSONObject dataJson = null;
//TODO query, get some dataJson
if(this.callBack != null)
this.callBack.async( dataJson );// asynchronize with MAIN LOOP THREAD
return dataJson;
}
@Override
protected void onProgressUpdate(Integer... values) {
super.onProgressUpdate(values);
if(this.callBack != null)
this.callBack.progress(values);// synchronize with MAIN LOOP THREAD
}
@Override
protected void onPostExecute(JSONObject jsonObject) {
super.onPostExecute(jsonObject);
if(this.callBack != null)
this.callBack.sync(jsonObject);// synchronize with MAIN LOOP THREAD
}
@Override
protected void onCancelled() {
super.onCancelled();
if(this.callBack != null)
this.callBack.cancel();
}
}
用法示例:
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
final Context _localContext = getContext();
SomeAsyncTask.CallBack someCallBack = new SomeAsyncTask.CallBack() {
@Override
public void async(JSONObject jsonResult) {//async thread
//some async process, e.g. send data to server...
}
@Override
public void sync(JSONObject jsonResult) {//sync thread
//get result...
//get some resource of Activity variable...
Resources resources = _localContext.getResources();
}
@Override
public void progress(Integer... status) {//sync thread
//e.g. change status progress bar...
}
@Override
public void cancel() {
}
};
new SomeAsyncTask( someCallBack )
.execute("someParams0", "someParams1", "someParams2");
}
