我正在试用面向 Android 开发人员的 Facebook 教程，但在第2 步遇到问题 - 个性化
我试图通过打字而不是复制和粘贴教程中的代码来学习，所以我可能打错了一些东西。我似乎找不到它。
我的 profilePicture 和用户名没有显示，因为即使我已授权该应用程序，用户似乎也为空。所以我的选择屏幕显示，但它显示的是一个空的用户配置文件。即使在上一个教程中，当我创建一个 LoginFragment 时，我的用户也没有显示在那里。有什么我做错了吗？
以下是我的完整代码减去导入语句和类声明
private static final int SPLASH = 0;
private static final int SELECTION = 1;
private static final int SETTINGS = 2;
private static final int FRAGMENT_COUNT = SETTINGS + 1;
private Fragment[] fragments = new Fragment[FRAGMENT_COUNT];
private static final String FRAGMENT_PREFIX = "fragment";
private static final String TAG = "MyFirstApp_FacebookMain.java";
private boolean isResumed = false;
private boolean restoredFragment = false;
private MenuItem settings;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_facebook_main);
for(int i=0; i < fragments.length; i++) {
restoreFragment(savedInstanceState, i);
}
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
FragmentManager manager = getSupportFragmentManager();
// Since we are only adding one fragment at a time, we can only save one.
Fragment f = manager.findFragmentById(R.id.body_frame);
for(int i=0; i < fragments.length; i++) {
if(fragments[i] == f) {
manager.putFragment(outState, getBundleKey(i), fragments[i]);
}
}
}
@Override
public void onResume() {
super.onResume();
isResumed = true;
}
@Override
public void onPause() {
super.onPause();
isResumed = false;
}
@Override
protected void onSessionStateChange(SessionState state, Exception exception) {
if(isResumed) {
FragmentManager manager = getSupportFragmentManager();
int backStackSize = manager.getBackStackEntryCount();
for(int i=0; i < backStackSize; i++) {
manager.popBackStack();
}
if(state.isOpened()) {
FragmentTransaction transaction = manager.beginTransaction();
transaction.replace(R.id.body_frame, fragments[SELECTION]).commit();
} else if (state.isClosed()) {
FragmentTransaction transaction = manager.beginTransaction();
transaction.replace(R.id.body_frame, fragments[SPLASH]).commit();
}
}
}
@Override
protected void onResumeFragments() {
super.onResumeFragments();
Session session = Session.getActiveSession();
if (session == null || session.getState().isClosed()) {
session = new Session(this);
Session.setActiveSession(session);
}
FragmentManager manager = getSupportFragmentManager();
if (restoredFragment) {
return;
}
// If we already have a valid token, then we can just open the session silently,
// otherwise present the splash screen and ask the user to login.
if (session.getState().equals(SessionState.CREATED_TOKEN_LOADED)) {
// no need to add any fragments here since it will be
// handled in onSessionStateChange
session.openForRead(this);
} else if (session.isOpened()) {
// if the session is already open, try to show the selection fragment
Fragment fragment = manager.findFragmentById(R.id.body_frame);
if (!(fragment instanceof SelectionFragment)) {
manager.beginTransaction().replace(R.id.body_frame,
fragments[SELECTION]).commit();
}
} else {
FragmentTransaction transaction = manager.beginTransaction();
transaction.replace(R.id.body_frame,
fragments[SPLASH]).commit();
}
}
private String getBundleKey(int index) {
return FRAGMENT_PREFIX + Integer.toString(index);
}
private void restoreFragment(Bundle savedInstanceState, int fragmentIndex) {
Fragment fragment = null;
if(savedInstanceState != null) {
FragmentManager manager = getSupportFragmentManager();
fragment = manager.getFragment(savedInstanceState, getBundleKey(fragmentIndex));
}
if(fragment != null) {
fragments[fragmentIndex] = fragment;
restoredFragment = true;
} else {
switch(fragmentIndex) {
case SPLASH:
fragments[SPLASH] = new SplashFragment();
break;
case SELECTION:
fragments[SELECTION] = new SelectionFragment();
break;
case SETTINGS:
fragments[SETTINGS] = new LoginFragment();
break;
default:
Log.w(TAG, "invalid fragment index");
break;
}
}
}
@Override
public boolean onPrepareOptionsMenu(Menu menu) {
FragmentManager manager = getSupportFragmentManager();
Fragment currentFragment = manager.findFragmentById(R.id.body_frame);
// only add the menu when the selection fragment is showing
if (currentFragment == fragments[SELECTION]) {
if (menu.size() == 0) {
settings = menu.add(R.string.settings);
}
return true;
} else {
menu.clear();
settings = null;
}
return false;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
if (item.equals(settings)) {
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.add(R.id.body_frame, fragments[SETTINGS]).addToBackStack(null).commit();
return true;
}
return false;
}
在 SelectionFragment.java 中
public class SelectionFragment extends Fragment {
private ProfilePictureView profilePictureView;
private TextView userNameView;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
super.onCreateView(inflater, container, savedInstanceState);
View view = inflater.inflate(R.layout.selection, container, false);
// Find the user's profile picture custom view
profilePictureView = (ProfilePictureView) view.findViewById(R.id.selection_profile_pic);
profilePictureView.setCropped(true);
// Find the user's name view
userNameView = (TextView) view.findViewById(R.id.selection_user_name);
// Get the active session
final Session session = Session.getActiveSession();
if (session != null && session.isOpened()) {
// if the session is open, make an API call to get user data
// and define a callback to handle the response
Request request = Request.newMeRequest(session, new Request.GraphUserCallback() {
@Override
public void onCompleted(GraphUser user, Response response) {
// if the response is successful
if (session == Session.getActiveSession()) {
if (user != null) {
// set the userid for the ProfilePictureView
// view that in turn displays the profile picture
profilePictureView.setProfileId(user.getId());
// set the textview to the user's name
userNameView.setText(user.getName());
}
}
}
});
Request.executeBatchAsync(request);
}
return view;
}
}
最后是 SplashFragment.java
public class SplashFragment extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.splash, container, false);
return view;
}
}