我有这个代码和我一起工作，我对控制流感到困惑。
这里的界面如何用作响应侦听器？如何在LoginActivity类中触发重写方法responseObject（JSONObject resp，String type）？
在调用AsyncTask之后控制权在哪里？
public class LoginActivity extends Activity implements ResponseListener{
login = (Button) findViewById(R.id.btnLogin);
login.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v)
{
String username = mUsernameField.getText().toString();
String password = mPasswordField.getText().toString();
String[] param = {username, password};
new ServerRequests.LoginUserAsyncTask(LoginActivity.this,this).execute(param);
}
@Override
public void responseObject(JSONObject resp, String type) {
try{
if (resp.has("api_key")) {
String api_key = resp.getString("api_key");
String user_id = resp.getString("user");
Log.i("api_key", api_key);
SharedPreferences settings = LoginActivity.this.getSharedPreferences(Constants.NADA_SP_KEY, 0);
final SharedPreferences.Editor editor = settings.edit();
editor.putString(Constants.NADA_API_KEY, api_key);
editor.putString(Constants.NADA_USER_ID, user_id);
editor.putBoolean(Constants.NADA_IS_LOGGED_IN, true);
editor.commit();
Log.i("first Visit", "False");
String should_show_questions_screen = resp.getString("should_set_basic_questions");
if (should_show_questions_screen.compareToIgnoreCase("true")==0){
Intent intent=new Intent(LoginActivity.this,RegistrationSuccessfulScreen.class);
startActivity(intent);
finish();
}else {
Intent intent = new Intent(LoginActivity.this, UserNavigationActivity.class);
startActivity(intent);
finish();
}
}
}catch (JSONException e){
e.printStackTrace();
}
}
//Heres my ServerRequest Class which uses AsyncTask
public class ServerRequests {
public static class LoginUserAsyncTask extends AsyncTask<String, Void, String> {
static JSONObject udetails;
Context mContext;
ResponseListener mResponseListener;
SweetAlertDialog progressDialog;
public LoginUserAsyncTask(Context mContext,ResponseListener listener) {
this.mContext = mContext;
this.mResponseListener = listener;
}
protected void onPreExecute() {
super.onPreExecute();
progressDialog =new SweetAlertDialog(mContext, SweetAlertDialog.PROGRESS_TYPE);
progressDialog.getProgressHelper().setBarColor(Color.parseColor("#A5DC86"));
progressDialog.setTitleText("please wait connecting..");
progressDialog.setCancelable(false);
progressDialog.show();
}
@Override
protected String doInBackground(String... params) {
HttpClient client = new DefaultHttpClient();
HttpPost post = null;
udetails = new JSONObject();
String response_data = "";
if (params.length == 2) {
try {
post = new HttpPost(Config.SERVER_BASE_URL + "/login");
udetails.put("username", params[0]);
udetails.put("password", params[1]);
SharedPreferences settings = mContext.getSharedPreferences(Constants.NADA_SP_KEY, 0);
final SharedPreferences.Editor editor = settings.edit();
editor.putString(Config.USER_NAME, params[0]).commit();
} catch (JSONException e) {
e.printStackTrace();
}
} else {
try {
post = new HttpPost(Config.SERVER_BASE_URL + "/login_with_fb");
udetails.put("fb_id", params[0]);
udetails.put("fb_auth_token", params[1]);
SharedPreferences settings = mContext.getSharedPreferences(Constants.NADA_SP_KEY, 0);
final SharedPreferences.Editor editor = settings.edit();
editor.putString(Config.USER_NAME, params[0]).commit();
} catch (JSONException e) {
e.printStackTrace();
}
}
try {
StringEntity se = new StringEntity(udetails.toString());
se.setContentType(new BasicHeader(HTTP.CONTENT_TYPE, "application/json"));
post.setEntity(se);
HttpResponse response = client.execute(post);
int response_code = response.getStatusLine().getStatusCode();
response_data = EntityUtils.toString(response.getEntity());
Log.i("api_token", response_data);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return response_data;
}
@Override
protected void onPostExecute(String response) {
progressDialog.dismiss();
JSONObject resp = new JSONObject();
try {
resp = new JSONObject(response);
if (resp.has("status")) {
if (resp.getString("status").compareToIgnoreCase("unauthorised")==0){
AppMsg appMsg = AppMsg.makeText((Activity)mContext, resp.getString("message"), style);
appMsg.show();
}
}
mResponseListener.responseObject(resp,"LOGIN");
} catch (JSONException e) {
AppMsg appMsg = AppMsg.makeText((Activity)mContext, "Something went wrong", style);
appMsg.show();
e.printStackTrace();
}
}
}
//Here's Interface Which has this method
public interface ResponseListener {
public void responseObject(JSONObject data,String type);
}
答案 0 :(得分：1)
您的LoginActivity实施ResponseListener。在这一行：new ServerRequests.LoginUserAsyncTask(LoginActivity.this,this).execute(param);中，您将活动两次传递到LoginUserAsyncTask构造函数中。请注意，构造函数接受Context和ResponseListener。您可以这样做，因为您的活动实现了ResponseListener。
现在LoginUserAsyncTask可以在您的激活上调用responseObject方法，因为它以ResponseListener为参考。它在onPostExecute的{{1}}方法中执行此操作。活动有点列出任务完成时，然后调用AsyncTask方法。
Becaus responseObject的工作是异步完成的，它会立即返回并执行下一个语句。
我也认为你缺少第一种方法。