我有一个回收站视图，当用户滚动到底部时，我从服务器加载一些数据我想显示进度条并向服务器发送另一个请求以获取更多数据。我尝试了下面的代码，但它无法从服务器加载更多数据。请帮忙
private RecyclerView mRecyclerView;
private List<User> mUsers = new ArrayList<>();
private UserAdapter mUserAdapter;
private static String sz_RecordCount;
private static String sz_LastCount;
private final int m_n_DefaultRecordCount = m_kDEFAULT_RECORD_COUNT;
private static final int m_kDEFAULT_RECORD_COUNT = 5;
private ArrayList<CDealAppDatastorage> s_oDataset;
private String TAG = MainActivity.class.getSimpleName();
private CDealAppDatastorage item;
private static int arrayCount;
private Context context;
private PreferenceHelper m_oPreferenceHelper;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
context = MainActivity.this;
m_oPreferenceHelper = new PreferenceHelper(context);
sz_RecordCount = String.valueOf(m_n_DefaultRecordCount);// increment of record count
int intialLastCount = 0;
sz_LastCount = String.valueOf(intialLastCount);// increment of last count...
s_oDataset = new ArrayList<>();// making object of Arraylist
//initial request for data
initalDealListing();
mRecyclerView = (RecyclerView) findViewById(R.id.recycleView);
mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
mUserAdapter = new UserAdapter();
mUserAdapter.setOnLoadMoreListener(new OnLoadMoreListener() {
@Override
public void onLoadMore() {
Log.e("haint", "Load More");
mUsers.add(null);
mUserAdapter.notifyItemInserted(mUsers.size() - 1);
//Load more data for reyclerview
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
Log.e("haint", "Load More 2");
//Remove loading item
mUsers.remove(mUsers.size() - 1);
mUserAdapter.notifyItemRemoved(mUsers.size());
//sending request to server for more data
moreDealsRequest();
mUserAdapter.notifyDataSetChanged();
mUserAdapter.setLoaded();
}
}, 5000);
}
});
}
private void initalDealListing() {
String m = "9565656565";
String p = "D55A8077E0208A5C5B25176608EF84BD";
// 3. build jsonObject
try {
final JSONObject jsonObject = new JSONObject();// making object of Jsons.
jsonObject.put("agentCode", m.trim());// put mobile number
jsonObject.put("pin", p.trim());// put password
jsonObject.put("recordcount", sz_RecordCount.trim());// put record count
jsonObject.put("lastcountvalue", sz_LastCount.trim());// put last count
Log.e("CAppList:", sz_RecordCount);
Log.e("Capplist:", sz_LastCount);
Log.d(TAG, "Server Request:-" + jsonObject.toString());
final String m_DealListingURL = APIStorage.IREWARDS_URL + APIStorage.DEALLISTING_URL;
JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.POST, m_DealListingURL, jsonObject, new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
Log.d(TAG, "Server Response:-" + response);
try {
int nResultCodeFromServer = Integer.parseInt(response.getString(ServerResponseStorage.s_szRESULT_CODE));
if (nResultCodeFromServer == ConstantInt.m_kTRANSACTION_SUCCESS) {
JSONArray posts = response.optJSONArray(ServerResponseStorage.s_szDEAL_ARRAY);// get Deal list in array from response
s_oDataset.clear();
for (int i = 0; i < posts.length(); i++) {// loop for counting deals from server
try {
JSONObject post = posts.getJSONObject(i);// counting deal based on index
item = new CDealAppDatastorage();// creating object of DealAppdata storage
item.setM_szHeaderText(post.getString(ServerResponseStorage.s_szDEAL_NAME));// get deal name from response
item.setM_szsubHeaderText(post.getString(ServerResponseStorage.s_szDEAL_CODE));// get dealcode from response
s_oDataset.add(item);// add all items in ArrayList
} catch (Exception e) {
e.printStackTrace();
}
}
arrayCount = posts.length();
Log.d(TAG, "ArrayCount::" + arrayCount);
/*here we are storing no. of deals coming from server*/
// write
m_oPreferenceHelper.saveIntegerValue("LastCountLength", arrayCount);
if (!s_oDataset.isEmpty()) {// condition if data in arraylist is not empty
mRecyclerView.setAdapter(mUserAdapter);
}
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Log.d(TAG, "Server error:-" + error);
}
});
RequestQueue requestQueue = Volley.newRequestQueue(context);
jsonObjectRequest.setRetryPolicy(new DefaultRetryPolicy(ConstantInt.INITIAL_TIMEOUT_MS, DefaultRetryPolicy.DEFAULT_MAX_RETRIES, DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));
requestQueue.add(jsonObjectRequest);
} catch (JSONException e) {
e.printStackTrace();
}
}
/*This method send request to server for more deals*/
private void moreDealsRequest() {
try {
// 3. build jsonObject
final JSONObject jsonObject = new JSONObject();// making object of Jsons.
jsonObject.put(ServerRequestKeyStorage.s_szAGENT_CODE, "9565656565");// put mobile number
jsonObject.put(ServerRequestKeyStorage.s_szPASSWORD, "D55A8077E0208A5C5B25176608EF84BD");// put password
jsonObject.put(ServerRequestKeyStorage.s_szRECORD_COUNT, sz_RecordCount.trim());// put record count
jsonObject.put(ServerRequestKeyStorage.s_szLAST_COUNT, sz_LastCount.trim());// put last count
Log.e("CAppList:", sz_RecordCount);
Log.e("Capplist:", sz_LastCount);
// 4. convert JSONObject to JSON to String
Log.e(TAG, "Server Request:-" + jsonObject.toString());
RequestQueue requestQueue = Volley.newRequestQueue(context);
final String imgPath = APIStorage.IREWARDS_URL + APIStorage.DEAL_IMAGE_PATH;
final String m_DealListingURL = APIStorage.IREWARDS_URL + APIStorage.DEALLISTING_URL;
JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.POST, m_DealListingURL, jsonObject, new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
Log.e(TAG, "Server Response:-" + response);
try {
int nResultCodeFromServer = Integer.parseInt(response.getString(ServerResponseStorage.s_szRESULT_CODE));
if (nResultCodeFromServer == ConstantInt.m_kTRANSACTION_SUCCESS) {
// Select the last row so it will scroll into view...
JSONArray posts = response.optJSONArray(ServerResponseStorage.s_szDEAL_ARRAY);// GETTING DEAL LIST
for (int i = 0; i < posts.length(); i++) {
try {
JSONObject post = posts.getJSONObject(i);// GETTING DEAL AT POSITION AT I
item = new CDealAppDatastorage();// object create of DealAppdatastorage
item.setM_szHeaderText(post.getString(ServerResponseStorage.s_szDEAL_NAME));//getting deal name
item.setM_szsubHeaderText(post.getString(ServerResponseStorage.s_szDEAL_CODE));// getting deal code
s_oDataset.add(item);
} catch (Exception e) {
e.printStackTrace();
}
}
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Log.d(TAG, "Server Error::" + error);
}
});
jsonObjectRequest.setRetryPolicy(new DefaultRetryPolicy(ConstantInt.INITIAL_TIMEOUT_MS, DefaultRetryPolicy.DEFAULT_MAX_RETRIES, DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));
requestQueue.add(jsonObjectRequest);
} catch (JSONException e) {
e.printStackTrace();
}
}
static class UserViewHolder extends RecyclerView.ViewHolder {
public TextView tvName;
public TextView tvEmailId;
public UserViewHolder(View itemView) {
super(itemView);
tvName = (TextView) itemView.findViewById(R.id.tvName);
tvEmailId = (TextView) itemView.findViewById(R.id.tvEmailId);
}
}
static class LoadingViewHolder extends RecyclerView.ViewHolder {
public ProgressBar progressBar;
public LoadingViewHolder(View itemView) {
super(itemView);
progressBar = (ProgressBar) itemView.findViewById(R.id.progressBar1);
}
}
class UserAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private final int VIEW_TYPE_ITEM = 0;
private final int VIEW_TYPE_LOADING = 1;
private OnLoadMoreListener mOnLoadMoreListener;
private boolean isLoading;
private int visibleThreshold = 5;
private int lastVisibleItem, totalItemCount;
public UserAdapter() {
final LinearLayoutManager linearLayoutManager = (LinearLayoutManager) mRecyclerView.getLayoutManager();
mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
totalItemCount = linearLayoutManager.getItemCount();
lastVisibleItem = linearLayoutManager.findLastVisibleItemPosition();
if (!isLoading && totalItemCount <= (lastVisibleItem + visibleThreshold)) {
if (mOnLoadMoreListener != null) {
mOnLoadMoreListener.onLoadMore();
}
isLoading = true;
}
}
});
}
public void setOnLoadMoreListener(OnLoadMoreListener mOnLoadMoreListener) {
this.mOnLoadMoreListener = mOnLoadMoreListener;
}
@Override
public int getItemViewType(int position) {
return s_oDataset.get(position) == null ? VIEW_TYPE_LOADING : VIEW_TYPE_ITEM;
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (viewType == VIEW_TYPE_ITEM) {
View view = LayoutInflater.from(MainActivity.this).inflate(R.layout.layout_user_item, parent, false);
return new UserViewHolder(view);
} else if (viewType == VIEW_TYPE_LOADING) {
View view = LayoutInflater.from(MainActivity.this).inflate(R.layout.layout_loading_item, parent, false);
return new LoadingViewHolder(view);
}
return null;
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
if (holder instanceof UserViewHolder) {
CDealAppDatastorage user = s_oDataset.get(position);
UserViewHolder userViewHolder = (UserViewHolder) holder;
userViewHolder.tvName.setText(user.getM_szHeaderText());
userViewHolder.tvEmailId.setText(user.getM_szsubHeaderText());
} else if (holder instanceof LoadingViewHolder) {
LoadingViewHolder loadingViewHolder = (LoadingViewHolder) holder;
loadingViewHolder.progressBar.setIndeterminate(true);
}
}
@Override
public int getItemCount() {
return s_oDataset == null ? 0 : s_oDataset.size();
}
public void setLoaded() {
isLoading = false;
}
}
}
答案 0 :(得分：2)
使用以下代码：
首先声明这些全局变量：
int visibleItemCount, totalItemCount = 1;
int firstVisiblesItems = 0;
int totalPages = 1; // get your total pages from web service first response
int current_page = 0;
boolean canLoadMoreData = true; // make this variable false while your web service call is going on.
LinearLayoutManager linearLayoutManager;
将布局管理器分配给您的Recyclerview：
linearLayoutManager = new LinearLayoutManager(mActivity);
mRecyclerView.setLayoutManager(linearLayoutManager);
滚动回收者视图的监听器：
mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
if (dy > 0) //check for scroll down
{
visibleItemCount = linearLayoutManager.getChildCount();
totalItemCount = linearLayoutManager.getItemCount();
firstVisiblesItems = linearLayoutManager.findFirstVisibleItemPosition();
if (canLoadMoreData) {
if ((visibleItemCount + firstVisiblesItems) >= totalItemCount) {
if (current_page < totalPages) {
canLoadMoreData = false;
/**
* .
* .
* .
* .call your webservice with page index
* .
* .
*
*/
//After completion of web service make 'canLoadMoreData = true'
}
}
}
}
}
});
答案 1 :(得分：1)
太晚了，但我也提到同样的方式检查我的代码对我有用
以下是使用改版的API调用并获取listnotifications然后在此方法中我为loadmore创建了另一个方法getMoreNotificationListApiCall()
public void getNotification()
{
if (listnotifications.size() > 0) {
notificationListAdapter = new NotificationListAdapter(NotificationListActivity.this, listnotifications, notificationListRecyclerview);
notificationListRecyclerview.setAdapter(notificationListAdapter);
notificationListAdapter.setOnLoadMoreListener(new OnLoadMoreListener() {
@Override
public void onLoadMore() {
Log.e("ad", "Load More");
listnotifications.add(null);
Handler handler = new Handler();
final Runnable r = new Runnable() {
public void run() {
if (listnotifications.size()>0) {
notificationListAdapter.notifyItemInserted(listnotifications.size() - 1);
}
}
};
handler.post(r);
try {
if (CommonUtils.isConnectingToInternet(NotificationListActivity.this)) {
// Internet Connection is Present
getMoreNotificationListApiCall();
} else {
//Remove loading item
if (listnotifications.size()>0) {
listnotifications.remove(listnotifications.size() - 1);
}
notificationListAdapter.notifyItemRemoved(listnotifications.size());
CommonUtils.commonToast(NotificationListActivity.this, getResources().getString(R.string.no_internet_exist));
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
}
}
getMoreNotificationListApiCall()方法代码我增加startlimit表示页面索引并删除null（我正在使用retorfit进行api调用）
private void getMoreNotificationListApiCall() {
try {
if (CommonUtils.isConnectingToInternet(NotificationListActivity.this)) {
StartLimit = StartLimit + 10;
Call<NotificationBase> call = ApiHandler.getApiService().getNotificationListApi(notificationListJsonMap());
call.enqueue(new Callback<NotificationBase>() {
@Override
public void onResponse(Call<NotificationBase> registerCall, Response<NotificationBase> response) {
Log.e(TAG, " Full json gson => " + "Hi i am here");
try {
Log.e(TAG, " Full json gson => " + new Gson().toJson(response));
JSONObject jsonObj = new JSONObject(new Gson().toJson(response).toString());
Log.e(TAG, " responce => " + jsonObj.getJSONObject("body").toString());
if (response.isSuccessful()) {
int success = response.body().getSuccess();
if (success == 1) {
List<NotificationBean> moreNotication = response.body().getNotificatons();
//Remove loading item
if (listnotifications.size() > 0) {
listnotifications.remove(listnotifications.size() - 1);
}
notificationListAdapter.notifyItemRemoved(listnotifications.size());
for (int i = 0; i < moreNotication.size(); i++) {
listnotifications.add(moreNotication.get(i));
}
notificationListAdapter.notifyDataSetChanged();
notificationListAdapter.setLoaded();
} else if (success == 0) {
if (listnotifications.size() > 0) {
listnotifications.remove(listnotifications.size() - 1);
}
notificationListAdapter.notifyItemRemoved(listnotifications.size());
} else {
if (listnotifications.size() > 0) {
listnotifications.remove(listnotifications.size() - 1);
}
notificationListAdapter.notifyItemRemoved(listnotifications.size());
}
} else {
if (listnotifications.size() > 0) {
listnotifications.remove(listnotifications.size() - 1);
}
notificationListAdapter.notifyItemRemoved(listnotifications.size());
}
} catch (Exception e) {
e.printStackTrace();
try {
Log.e(TAG, "error=" + e.toString());
if (listnotifications.size() > 0) {
listnotifications.remove(listnotifications.size() - 1);
}
notificationListAdapter.notifyItemRemoved(listnotifications.size());
} catch (Resources.NotFoundException e1) {
e1.printStackTrace();
}
}
}
@Override
public void onFailure(Call<NotificationBase> call, Throwable t) {
try {
Log.e(TAG, "error" + t.toString());
if (listnotifications.size() > 0) {
listnotifications.remove(listnotifications.size() - 1);
}
notificationListAdapter.notifyItemRemoved(listnotifications.size());
} catch (Resources.NotFoundException e) {
e.printStackTrace();
}
}
});
} else {
CommonUtils.commonToast(NotificationListActivity.this, getResources().getString(R.string.no_internet_exist));
}
} catch (Resources.NotFoundException e) {
e.printStackTrace();
}
}
这是我的适配器类，其中我实现了OnLoadMoreListener
public class NotificationListAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
public static List<NotificationBean> mList;
private final int VIEW_TYPE_ITEM = 0;
private final int VIEW_TYPE_LOADING = 1;
FragmentActivity mFragmentActivity;
private OnLoadMoreListener mOnLoadMoreListener;
private boolean isLoading;
private int visibleThreshold = 5;
private int lastVisibleItem, totalItemCount;
public NotificationListAdapter(FragmentActivity fragmentActivity, List<NotificationBean> data, RecyclerView mRecyclerView) {
this.mList = data;
this.mFragmentActivity = fragmentActivity;
final LinearLayoutManager linearLayoutManager = (LinearLayoutManager) mRecyclerView.getLayoutManager();
mRecyclerView.addOnScrollListener( new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
totalItemCount = linearLayoutManager.getItemCount();
lastVisibleItem = linearLayoutManager.findLastVisibleItemPosition();
if (!isLoading && totalItemCount <= (lastVisibleItem + visibleThreshold)) {
if (mOnLoadMoreListener != null) {
mOnLoadMoreListener.onLoadMore();
}
isLoading = true;
}
}
});
}
public void setOnLoadMoreListener(OnLoadMoreListener mOnLoadMoreListener) {
this.mOnLoadMoreListener = mOnLoadMoreListener;
}
@Override
public int getItemViewType(int position) {
return mList.get(position) == null ? VIEW_TYPE_LOADING : VIEW_TYPE_ITEM;
}
public void delete(int position) { //removes the row
Log.e("Position : ", "" + position);
mList.remove(position);
notifyItemRemoved(position);
notifyItemRangeChanged(position, mList.size());
}
// Return the size arraylist
@Override
public int getItemCount() {
return mList == null ? 0 : mList.size();
}
public void setLoaded() {
isLoading = false;
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (viewType == VIEW_TYPE_ITEM) {
// create a new view
View itemLayoutView = LayoutInflater.from(parent.getContext()).inflate(
R.layout.item_notification_list, parent, false);
return new ViewHolder(itemLayoutView);
} else if (viewType == VIEW_TYPE_LOADING) {
View itemLayoutView = LayoutInflater.from(parent.getContext()).inflate(
R.layout.loading_layout, parent, false);
return new LoadingViewHolder(itemLayoutView);
}
return null;
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, final int position) {
if (holder instanceof ViewHolder) {
try {
final ViewHolder viewHolder = (ViewHolder) holder;
viewHolder.singleBean = mList.get(position);
viewHolder.pos = position;
final NotificationBean list = mList.get(position);
String notificationTitle = list.getMessage();
String notificationTimeDate = list.getCreatedDatetime();
String notificationIsRead = list.getIsRead();
} catch (Exception e) {
e.printStackTrace();
}
} else if (holder instanceof LoadingViewHolder) {
LoadingViewHolder loadingViewHolder = (LoadingViewHolder) holder;
loadingViewHolder.progressBar.setIndeterminate(true);
}
}
static class LoadingViewHolder extends RecyclerView.ViewHolder {
public ProgressBar progressBar;
public LoadingViewHolder(View itemView) {
super(itemView);
progressBar = (ProgressBar) itemView.findViewById(R.id.progressBar1);
}
}
public class ViewHolder extends RecyclerView.ViewHolder {
public NotificationBean singleBean;
int pos;
TextView txt_notification_time_date;
CustomTextview checkbox_notification;
RelativeLayout rl_row_background;
public ViewHolder(final View v) {
super(v);
checkbox_notification = (CustomTextview) v.findViewById(R.id.checkbox_notification);
//checkbox_notification.setButtonDrawable(android.R.color.transparent);//custom_checkbox
// txt_notification_title= (TextView) v.findViewById(R.id.txt_notification_title);
txt_notification_time_date = (TextView) v.findViewById(R.id.txt_notification_time_date);
rl_row_background = (RelativeLayout) v.findViewById(R.id.rl_row_background);
}
}
public void refreshAdapter() {
notifyDataSetChanged();
}
}
这里是xml文件 loading_layout.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:gravity="center_horizontal"
android:orientation="vertical">
<ProgressBar
android:id="@+id/progressBar1"
style="@style/Widget.AppCompat.ProgressBar.Horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content" android:layout_marginBottom="5dp"
android:layout_marginTop="5dp"
android:indeterminate="true" />
</LinearLayout>
答案 2 :(得分：0)
从服务器获取数据是异步任务。所以你需要把它包围起来 runOnUiThread runnable中的更新代码。改变用户界面。
runOnUiThread(new Runnable() {
@Override
public void run() {
mUsers.remove(mUsers.size() - 1);
mUserAdapter.notifyItemRemoved(mUsers.size());
//sending request to server for more data
moreDealsRequest();
mUserAdapter.notifyDataSetChanged();
mUserAdapter.setLoaded();
}});