如何在服务器的回收器视图中加载更多数据? [英] How to load more data in recycler view from server?
本文介绍了如何在服务器的回收器视图中加载更多数据?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我有一个回收站视图，当用户滚动到底部时，我从服务器中加载一些数据，我想显示一个进度条，并向服务器发送另一个请求以获取更多数据.我试过下面的代码，但它无法从服务器加载更多数据.请帮助
I have a recycler view in which I load some data from the server when user scroll to bottom I want to show a progress bar and send another request to the server for more data. I have tried below code but it not able to load more data from the server. please help
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;
}
}
}
推荐答案
使用以下代码:
首先声明以下全局变量:
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;
将布局管理器分配到您的Recyclerview:
linearLayoutManager = new LinearLayoutManager(mActivity);
mRecyclerView.setLayoutManager(linearLayoutManager);
滚动回收器视图的侦听器:
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'
}
}
}
}
}
});
这篇关于如何在服务器的回收器视图中加载更多数据?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
查看全文
