我使用ViewPager能够在视图之间滑动。我面临的问题是，第一页没有正确渲染(只有布局文件中的静态成员被渲染)，但第二页和进一步的页面被正确渲染。另外，当我转到第三页或之后的页面，然后滑回第一页时，它会被完美地呈现。
我知道ViewPager在开始时加载第一页和第二页，并为每个下一页做同样的事情。这是我的第一页没有正确呈现的原因吗?我正在对每个页面进行网络呼叫，返回的数据正在页面上显示。
下面是我的Adapter的代码:
public class SlidingImageDetailAdapter extends PagerAdapter implements GoogleApiClient.OnConnectionFailedListener {
Context context;
List<ImageDetailData> list;
List<LatestComment> latestComments;
LayoutInflater layoutInflater;
GaApplication application;
protected GoogleApiClient mGoogleApiClient;
TinyDB tinyDB;
MixpanelAPI mixpanel;
RestAdapter restAdapter;
public final String TAG = getClass().getSimpleName();
private static int radius = Utils.dpToPx(40);
private String googlePlaceId = null;
private String finalPlace = null;
private String commentId = null;
private String imageId = null;
private String imageUrl = null;
private boolean updateNeeded;
private PlaceAutocompleteAdapter mAdapter;
ImageGalleryAdapter imageGalleryAdapter;
ImageCommentAdapter imageCommentAdapter;
ViewHolder holder = null;
private static final LatLngBounds BOUNDS_GREATER_SYDNEY = new LatLngBounds(
new LatLng(-34.041458, 150.790100), new LatLng(-33.682247, 151.383362));
public SlidingImageDetailAdapter(Context context, List<ImageDetailData> list) {
this.context = context;
this.list = list;
layoutInflater = LayoutInflater.from(context);
application = (GaApplication) ((AppCompatActivity) context).getApplication();
String API = application.getAPI();
tinyDB = new TinyDB(context);
mixpanel = MixpanelAPI.getInstance(context, application.getMixpanelId());
final String token = tinyDB.getString(AppConstants.GA_ACCESS_TOKEN);
OkHttpClient okHttpClient = new OkHttpClient();
RequestInterceptor requestInterceptor = new RequestInterceptor() {
@Override
public void intercept(RequestFacade request) {
request.addHeader("Accept", "application/json");
request.addHeader("Authorization", "Token " + token);
}
};
restAdapter = new RestAdapter.Builder()
.setClient(new OkClient(okHttpClient))
.setLogLevel(RestAdapter.LogLevel.FULL)
.setEndpoint(API)
.setRequestInterceptor(requestInterceptor)
.build();
mGoogleApiClient = new GoogleApiClient.Builder(context)
.enableAutoManage((ImageDetailSliderActivity)context, 0 /* clientId */, this)
.addApi(Places.GEO_DATA_API)
.build();
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((View) object);
}
@Override
public Object instantiateItem(ViewGroup container, int position) {
LogUtil.i(TAG, "instantiateItem called");
View view = layoutInflater.inflate(R.layout.viewpager_image_detail, container, false);
holder = new ViewHolder(view);
final ImageDetailData item = list.get(position);
imageId = item.getPhotoId();
holder.bar.setVisibility(View.INVISIBLE);
holder.deletePhoto.setVisibility(View.INVISIBLE);
holder.locationIcon.setVisibility(View.GONE);
holder.galleryList.setFocusable(false);
holder.commentList.setFocusable(false);
googlePlaceId = null;
finalPlace = null;
updateNeeded = false;
commentId = null;
imageUrl = null;
final ProgressDialog progressDialog = new ProgressDialog(context);
progressDialog.setMessage("Loading...");
progressDialog.setCanceledOnTouchOutside(false);
progressDialog.show();
if (!TextUtils.isEmpty(item.getPhotoUrl())) {
imageUrl = item.getPhotoUrl();
Uri uri = Uri.parse(item.getPhotoUrl());
ImageRequest request = ImageRequestBuilder.newBuilderWithSource(uri)
.setProgressiveRenderingEnabled(true)
.build();
DraweeController controller = Fresco.newDraweeControllerBuilder()
.setImageRequest(request)
.setOldController(holder.image.getController())
.build();
holder.image.setController(controller);
}
Picasso.with(context)
.load(tinyDB.getString(AppConstants.USER_DP))
.resize(radius, radius)
.centerCrop()
.transform(new CircleTransform())
.into(holder.userDp);
TextWatcher textWatcher = new TextWatcher() {
public void afterTextChanged(Editable s) {
Picasso.with(context)
.load(R.drawable.cta_button_post)
.into(holder.postButton);
}
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
public void onTextChanged(CharSequence s, int start, int before,
int count) {
if (TextUtils.isEmpty(holder.writeComment.getText().toString().trim())) {
Picasso.with(context)
.load(R.drawable.cta_button_post_in_active)
.into(holder.postButton);
} else {
Picasso.with(context)
.load(R.drawable.cta_button_post)
.into(holder.postButton);
}
}
};
holder.writeComment.addTextChangedListener(textWatcher);
holder.comment.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
scrollToComment();
}
});
holder.seeAll.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(context, AllGalleriesActivity.class);
intent.putExtra(KEY_SEND_ALL_GALLERY_PHOTO_ID, item.getPhotoId());
context.startActivity(intent);
}
});
//show and hide fab based on whether autocomplete textview has focus or not
holder.autoCompleteTextView.setOnFocusChangeListener(new View.OnFocusChangeListener() {
@Override
public void onFocusChange(View v, boolean hasFocus) {
if (hasFocus) {
((ImageDetailSliderActivity)context).hideFab();
} else {
((ImageDetailSliderActivity)context).showFab();
}
}
});
LogUtil.i(TAG, "Id of image = " + item.getPhotoId());
PhotoAPI photoAPI = restAdapter.create(PhotoAPI.class);
photoAPI.getFeed(item.getPhotoId(), new Callback<ImageItem>() {
@Override
public void success(final ImageItem photoDetails, Response response) {
LogUtil.i(TAG, "photo api successful");
DialogUtils.safelyDismissDialog(progressDialog);
holder.locationIcon.setVisibility(View.VISIBLE);
if (TextUtils.isEmpty(item.getPhotoUrl())) {
imageUrl = photoDetails.getPhotoUrl();
item.setPhotoUrl(photoDetails.getPhotoUrl());
Uri uri = Uri.parse(photoDetails.getPhotoUrl());
ImageRequest request = ImageRequestBuilder.newBuilderWithSource(uri)
.setProgressiveRenderingEnabled(true)
.build();
DraweeController controller = Fresco.newDraweeControllerBuilder()
.setImageRequest(request)
.setOldController(holder.image.getController())
.build();
holder.image.setController(controller);
}
if (photoDetails.isOwner()) {
holder.buttonBookmark.setVisibility(View.GONE);
holder.bar.setVisibility(View.VISIBLE);
holder.deletePhoto.setVisibility(View.VISIBLE);
holder.separator.setVisibility(View.VISIBLE);
if (TextUtils.isEmpty(photoDetails.getCaption())) {
holder.addCaption.setVisibility(View.VISIBLE);
} else {
holder.updateCaption1.setVisibility(View.VISIBLE);
}
if (TextUtils.isEmpty(photoDetails.getLocation())) {
holder.loc.setVisibility(View.GONE);
showAutoComplete();
} else {
holder.loc.setVisibility(View.VISIBLE);
holder.location.setText(photoDetails.getLocation());
showEditOrRemove();
}
if (photoDetails.getCampaignInfo() != null) {
showCleartripCampaign(photoDetails.getCampaignInfo());
} else {
showAddToExisting();
}
} else {
if (TextUtils.isEmpty(photoDetails.getLocation())) {
holder.loc.setVisibility(View.GONE);
} else {
holder.loc.setVisibility(View.VISIBLE);
holder.location.setText(photoDetails.getLocation());
}
}
if (!TextUtils.isEmpty(photoDetails.getCaption())) {
holder.caption.setText(photoDetails.getCaption());
} else {
holder.caption.setVisibility(View.GONE);
}
holder.time.setText(photoDetails.getTime());
holder.username.setText(photoDetails.getUserName());
holder.userFives.setText(String.format("%s Karma", Integer.toString(photoDetails.getUserKarma())));
holder.numComments.setText(Integer.toString(photoDetails.getNumComments()));
holder.numComments.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(context, CommentsActivity.class);
intent.putExtra(KEY_SEND_PHOTO_ID, item.getPhotoId());
context.startActivity(intent);
}
});
holder.commentIcon.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(context, CommentsActivity.class);
intent.putExtra(KEY_SEND_PHOTO_ID, item.getPhotoId());
context.startActivity(intent);
}
});
holder.updateCaption1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
updateCaption();
}
});
holder.addCaption.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
updateCaption();
}
});
Picasso.with(context)
.load(photoDetails.getProfilePic())
.placeholder(R.drawable.feed_shape_profile_pic)
.resize(radius, radius)
.centerCrop()
.transform(new CircleTransform())
.into(holder.profilePic);
holder.profilePic.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(context, UserProfileActivity.class);
intent.putExtra(KEY_SEND_USER_ID, Integer.toString(photoDetails.getOwnerPk()));
context.startActivity(intent);
}
});
imageGalleryAdapter = new ImageGalleryAdapter(context, photoDetails.getGalleries(), item.getPhotoId());
holder.galleryList.setAdapter(imageGalleryAdapter);
setListViewHeightBasedOnChildren(holder.galleryList);
latestComments = photoDetails.getLatestComments();
imageCommentAdapter = new ImageCommentAdapter(context, latestComments);
holder.commentList.setAdapter(imageCommentAdapter);
setListViewHeightBasedOnChildren(holder.commentList);
if (photoDetails.isBookmarked()) {
Picasso.with(context)
.load(R.drawable.cta_button_bookmark_secondary_state)
.into(holder.buttonBookmark);
} else {
Picasso.with(context)
.load(R.drawable.cta_button_bookmark_default_state)
.into(holder.buttonBookmark);
}
holder.buttonBookmark.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (!photoDetails.isBookmarked()) {
Picasso.with(context)
.load(R.drawable.cta_button_bookmark_secondary_state)
.into(holder.buttonBookmark);
photoDetails.setIsBookmarked(true);
BookmarkUserAPI api = restAdapter.create(BookmarkUserAPI.class);
api.post(Integer.toString(photoDetails.getOwnerPk()), new Callback<ActionResponse>() {
@Override
public void success(ActionResponse actionResponse, Response response) {
LogUtil.i(TAG, "bookmark successful");
}
@Override
public void failure(RetrofitError error) {
LogUtil.i(TAG, "bookmark failed");
}
});
} else {
Picasso.with(context)
.load(R.drawable.cta_button_bookmark_default_state)
.into(holder.buttonBookmark);
photoDetails.setIsBookmarked(false);
UnBookmarkUserAPI api = restAdapter.create(UnBookmarkUserAPI.class);
api.post(Integer.toString(photoDetails.getOwnerPk()), new Callback<ActionResponse>() {
@Override
public void success(ActionResponse actionResponse, Response response) {
LogUtil.i(TAG, "unbookmark successful");
}
@Override
public void failure(RetrofitError error) {
LogUtil.i(TAG, "unbookmark failed");
}
});
}
}
});
holder.deletePhoto.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
updateNeeded = true;
FeedFragment.updateDelete(updateNeeded);
GalleryActivity.updateDelete(updateNeeded);
updateNeeded = !updateNeeded;
final Dialog dialog = new Dialog(context);
dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
dialog.setContentView(R.layout.dialog_delete);
dialog.show();
TextView cancel = (TextView) dialog.findViewById(R.id.textView174);
cancel.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
DialogUtils.safelyDismissDialog(dialog);
}
});
TextView deleteButton = (TextView) dialog.findViewById(R.id.textView175);
deleteButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
DeletePhotoAPI deletePhotoAPI = restAdapter.create(DeletePhotoAPI.class);
deletePhotoAPI.delete(item.getPhotoId(), new Callback<ActionResponse>() {
@Override
public void success(ActionResponse actionResponse, Response response) {
LogUtil.i(TAG, "image deleted successfully");
Toast.makeText(context.getApplicationContext(), "Image deleted successfully", Toast.LENGTH_SHORT).show();
((ImageDetailSliderActivity) context).finish();
}
@Override
public void failure(RetrofitError error) {
LogUtil.i(TAG, "image could not be deleted");
}
});
}
});
}
});
commentId = Integer.toString(photoDetails.getPk());
holder.postButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
postComment();
}
});
holder.image.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(context, AlternateFullImageActivity.class);
intent.putExtra(KEY_SEND_PHOTO_ID, item.getPhotoId());
intent.putExtra(KEY_SEND_PHOTO_URL, item.getPhotoUrl());
intent.setFlags(Intent.FLAG_ACTIVITY_NO_ANIMATION);
context.startActivity(intent);
((ImageDetailSliderActivity)context).overridePendingTransition(R.anim.fade_in, R.anim.fade_out);
}
});
}
@Override
public void failure(RetrofitError error) {
LogUtil.i(TAG, "photo api failed");
}
});
container.addView(view);
return view;
}
@Override
public int getCount() {
return list == null ? 0 : list.size();
}
@Override
public boolean isViewFromObject(View view, Object object) {
return view.equals(object);
}
@Override
public void onConnectionFailed(ConnectionResult connectionResult) {
LogUtil.i(TAG, "onConnectionFailed called");
}
public static class ViewHolder {
@Bind(R.id.imageView102)
SimpleDraweeView image;
@Bind(R.id.textView38)
TextView caption;
@Bind(R.id.textView39)
TextView time;
@Bind(R.id.textView45)
TextView username;
@Bind(R.id.textView46)
TextView userFives;
@Bind(R.id.imageView107)
ImageView profilePic;
@Bind(R.id.listView2)
ListView galleryList;
@Bind(R.id.textView57)
TextView seeAll;
@Bind(R.id.listView6)
ListView commentList;
@Bind(R.id.editText6)
EditText writeComment;
@Bind(R.id.imageView108)
ImageView buttonBookmark;
@Bind(R.id.imageView233)
ImageView editButton;
@Bind(R.id.textView151)
TextView numComments;
@Bind(R.id.textView82)
TextView bar;
@Bind(R.id.textView83)
TextView deletePhoto;
@Bind(R.id.textView79)
TextView comment;
@Bind(R.id.imageView116)
ImageView userDp;
@Bind(R.id.rel)
RelativeLayout rel;
@Bind(R.id.imageView131)
ImageView postButton;
@Bind(R.id.editText15)
EditText editCaption;
@Bind(R.id.textView184)
TextView separator;
@Bind(R.id.textView185)
TextView updateCaption1;
@Bind(R.id.textView186)
TextView updateCaption2;
@Bind(R.id.loc)
LinearLayout loc;
@Bind(R.id.textView115)
TextView location;
@Bind(R.id.locAuto)
RelativeLayout locAuto;
@Bind(R.id.autoCompleteTextView)
AutoCompleteTextView autoCompleteTextView;
@Bind(R.id.locEdit)
LinearLayout locEdit;
@Bind(R.id.editLocation)
TextView editLocation;
@Bind(R.id.removeLocation)
TextView removeLocation;
@Bind(R.id.scrollView)
ScrollView scrollView;
@Bind(R.id.imageView173)
ImageView locationIcon;
@Bind(R.id.textView5)
TextView addCaption;
@Bind(R.id.imageView11)
ImageView commentIcon;
public ViewHolder(View view) {
ButterKnife.bind(this, view);
}
}
}
只需将此方法添加到您的类
@Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
每次进入特定布局时都会渲染。