我正在尝试使用facebook graph api为我的课程项目制作一个Facebook应用程序。我有这些代码，但是当我第一次打开它或第一次登录时，我的asynctasks不起作用，但是当我关闭它并再次打开时，它会显示我需要的东西。请帮忙。
PageHomeFeed.java
public class PageFeedHome extends Fragment {
ArrayList<HashMap<String, String>> feedList;
private static final String TAG_ID = "id";
private static final String TAG_NAME = "name";
private static final String TAG_MESSAGE = "message";
private String feedMessage;
ListView listView;
BaseAdapter adapter;
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
final View view = inflater.inflate(R.layout.feed_home_activity,
container, false);
listView = (ListView) view.findViewById(R.id.feed_lv);
feedList = new ArrayList<HashMap<String, String>>();
new LoadPosts().execute();
adapter = new SimpleAdapter(getActivity(), feedList,
R.layout.feed_item_view, new String[] { TAG_MESSAGE, TAG_NAME,
TAG_ID }, new int[] { R.id.message, R.id.author, R.id.id_tv });
listView.setAdapter(adapter);
return view;
}
private class LoadPosts extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... params) {
// TODO Auto-generated method stub
Session.openActiveSession(getActivity(), true,
new Session.StatusCallback() {
// callback when session changes state
@Override
public void call(Session session, SessionState state,
Exception exception) {
if (session.isOpened()) {
new Request(session, "/163340583656/feed",
null, HttpMethod.GET,
new Request.Callback() {
public void onCompleted(
Response response) {
/* handle the result */
Log.i("PostFeedResponse", response.toString());
try {
GraphObject graphObj = response
.getGraphObject();
JSONObject json = graphObj
.getInnerJSONObject();
JSONArray jArray = json
.getJSONArray("data");
for (int i = 0; i < jArray.length(); i++) {
JSONObject currObj = jArray.getJSONObject(i);
final String feedId =currObj.getString("id");
if (currObj.has("message")) {
feedMessage = currObj.getString("message");
} else if (currObj.has("story")) {
feedMessage = currObj.getString("story");
} else {
feedMessage = "Posted a something";
}
JSONObject fromObj = currObj.getJSONObject("from");
String from = fromObj.getString("name");
HashMap<String, String> feed = new HashMap<String, String>();
feed.put(TAG_ID, feedId);
feed.put(TAG_MESSAGE, feedMessage);
feed.put(TAG_NAME, from);
feedList.add(feed);
}
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}).executeAsync();
}
}
});
return null;
}
@Override
protected void onPostExecute(String result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
Toast.makeText(getActivity(), ""+feedList.size(), Toast.LENGTH_LONG).show();
}
}
}
DashboardFragment.java
public class DashboardFragment extends Fragment {
Bundle params;
String url;
Bitmap bm;
static ImageView prof_pic;
static URL img_url;
static Context context;
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
final View view = inflater.inflate(R.layout.dashboard_activity,
container, false);
context = getActivity();
params = new Bundle();
params.putBoolean("redirect", false);
params.putString("height", "200");
params.putString("type", "normal");
params.putString("width", "200");
prof_pic = (ImageView) view.findViewById(R.id.profile_picture);
// start Facebook Login
Session.openActiveSession(getActivity(), true,
new Session.StatusCallback() {
// callback when session changes state
@Override
public void call(Session session, SessionState state,
Exception exception) {
if (session.isOpened()) {
// make request to the /me API
Request.newMeRequest(session,
new Request.GraphUserCallback() {
// callback after Graph API response
// with user object
@Override
public void onCompleted(GraphUser user,
Response response) {
if (user != null) {
TextView welcome = (TextView) view
.findViewById(R.id.user_name);
welcome.setText("Hello "
+ user.getName() + "!");
}
}
}).executeAsync();
new Request(session, "/me/picture", params,
HttpMethod.GET, new Request.Callback() {
public void onCompleted(
Response response) {
/* handle the result */
Log.i("PictureResponse",
response.toString());
try {
GraphObject graphObj = response.getGraphObject();
JSONObject json = graphObj.getInnerJSONObject();
JSONObject dataObj = json.getJSONObject("data");
url = dataObj.getString("url");
new LoadImage().execute(url);
Log.i("URL picture", url);
} catch (JSONException e) {
// TODO Auto-generated catch
e.printStackTrace();
}
}
}).executeAsync();
}
}
});
Button logout_btn = (Button) view.findViewById(R.id.logout);
logout_btn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
showHashKey(getActivity());
callFacebookLogout(getActivity());
}
});
return view;
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
Session.getActiveSession().onActivityResult(getActivity(), requestCode,
resultCode, data);
}
/**
* Logout From Facebook
*/
public void callFacebookLogout(Context context) {
Session session = Session.getActiveSession();
if (session != null) {
if (!session.isClosed()) {
session.closeAndClearTokenInformation();
Intent i = new Intent(getActivity(), ForwardMainActivity.class);
startActivity(i);
// clear your preferences if saved
}
} else {
session = new Session(context);
Session.setActiveSession(session);
session.closeAndClearTokenInformation();
Intent i = new Intent(getActivity(), ForwardMainActivity.class);
startActivity(i);
}
}
public static void showHashKey(Context context) {
try {
PackageInfo info = context.getPackageManager().getPackageInfo(
"com.albor.usjrforward", PackageManager.GET_SIGNATURES); // Your
// package
// name
// here
for (Signature signature : info.signatures) {
MessageDigest md = MessageDigest.getInstance("SHA");
md.update(signature.toByteArray());
Log.i("KeyHash:",
Base64.encodeToString(md.digest(), Base64.DEFAULT));
}
} catch (NameNotFoundException e) {
} catch (NoSuchAlgorithmException e) {
}
}
private class LoadImage extends AsyncTask<String, String, Bitmap> {
@Override
protected void onPreExecute() {
super.onPreExecute();
// pDialog = new ProgressDialog(MainActivity.this);
// pDialog.setMessage("Loading Image ....");
// pDialog.show();
}
protected Bitmap doInBackground(String... args) {
try {
bm = BitmapFactory.decodeStream((InputStream)new URL(args[0]).getContent());
} catch (Exception e) {
e.printStackTrace();
}
return bm;
}
protected void onPostExecute(Bitmap image) {
if(image != null){
prof_pic.setImageBitmap(image);
// pDialog.dismiss();
}else{
// pDialog.dismiss();
// Toast.makeText(MainActivity.this, "Image Does Not exist or Network Error", Toast.LENGTH_SHORT).show();
}
}
}
}
答案 0 :(得分：0)
我认为你得到race condition。移动此代码：
adapter = new SimpleAdapter(getActivity(), feedList,
R.layout.feed_item_view, new String[] { TAG_MESSAGE, TAG_NAME,
TAG_ID }, new int[] { R.id.message, R.id.author, R.id.id_tv });
listView.setAdapter(adapter);
致LoadPosts onPostExecute以确保数据已加载。