我用json做无限的再循环视图。
这段代码只能工作一半
我可以看到第一次装入的物品
但是当我向下滚动时，
什么都没发生，
我想，也许onLoadMore（）不起作用
我被编辑了4小时
指导我
我应该在哪里编辑？
感谢您对此感兴趣。
MainActivity
package com.androidcss.jsonexample;
import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.widget.Toast;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
// CONNECTION_TIMEOUT and READ_TIMEOUT are in milliseconds
public static final int CONNECTION_TIMEOUT = 10000;
public static final int READ_TIMEOUT = 15000;
private RecyclerView mRVFishPrice;
private AdapterFish mAdapter;
protected Handler handler;
List<DataFish> data=new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Make call to AsyncTask
new AsyncLogin().execute();
handler = new Handler();
mRVFishPrice = (RecyclerView)findViewById(R.id.fishPriceList);
mAdapter = new AdapterFish(MainActivity.this, data, mRVFishPrice);
mRVFishPrice.setAdapter(mAdapter);
mRVFishPrice.setLayoutManager(new LinearLayoutManager(MainActivity.this));
mAdapter.setOnLoadMoreListener(new AdapterFish.OnLoadMoreListener() {
@Override
public void onLoadMore() {
//add progress item
data.add(null);
mAdapter.notifyItemInserted(data.size() - 1);
handler.postDelayed(new Runnable() {
@Override
public void run() {
new AsyncLogin().execute();
}
}, 2000);
System.out.println("load");
}
});
}
private class AsyncLogin extends AsyncTask<String, String, String> {
ProgressDialog pdLoading = new ProgressDialog(MainActivity.this);
HttpURLConnection conn;
URL url = null;
@Override
protected void onPreExecute() {
super.onPreExecute();
//this method will be running on UI thread
pdLoading.setMessage("\tLoading...");
pdLoading.setCancelable(false);
pdLoading.show();
}
@Override
protected String doInBackground(String... params) {
try {
// Enter URL address where your json file resides
// Even you can make call to php file which returns json data
url = new URL("http://10.0.2.2/test/example.json");
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
return e.toString();
}
try {
// Setup HttpURLConnection class to send and receive data from php and mysql
conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(READ_TIMEOUT);
conn.setConnectTimeout(CONNECTION_TIMEOUT);
conn.setRequestMethod("GET");
// setDoOutput to true as we recieve data from json file
conn.setDoOutput(true);
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
return e1.toString();
}
try {
int response_code = conn.getResponseCode();
// Check if successful connection made
if (response_code == HttpURLConnection.HTTP_OK) {
// Read data sent from server
InputStream input = conn.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(input));
StringBuilder result = new StringBuilder();
String line;
while ((line = reader.readLine()) != null) {
result.append(line);
}
// Pass data to onPostExecute method
return (result.toString());
} else {
return ("unsuccessful");
}
} catch (IOException e) {
e.printStackTrace();
return e.toString();
} finally {
conn.disconnect();
}
}
@Override
protected void onPostExecute(String result) {
//this method will be running on UI thread
pdLoading.dismiss();
List<DataFish> data=new ArrayList<>();
pdLoading.dismiss();
try {
JSONArray jArray = new JSONArray(result);
// Extract data from json and store into ArrayList as class objects
for(int i=0;i<jArray.length();i++){
JSONObject json_data = jArray.getJSONObject(i);
DataFish fishData = new DataFish();
fishData.fishImage= json_data.getString("fish_img");
fishData.fishName= json_data.getString("fish_name");
fishData.catName= json_data.getString("cat_name");
fishData.sizeName= json_data.getString("size_name");
fishData.price= json_data.getInt("price");
data.add(fishData);
}
// Setup and Handover data to recyclerview
mRVFishPrice = (RecyclerView)findViewById(R.id.fishPriceList);
mAdapter = new AdapterFish(MainActivity.this, data, mRVFishPrice);
mRVFishPrice.setAdapter(mAdapter);
mRVFishPrice.setLayoutManager(new LinearLayoutManager(MainActivity.this));
} catch (JSONException e) {
Toast.makeText(MainActivity.this, e.toString(), Toast.LENGTH_LONG).show();
}
}
}
}
AdapterFish.java
package com.androidcss.jsonexample;
import android.content.Context;
import android.support.v4.content.ContextCompat;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;
import com.bumptech.glide.Glide;
import java.util.Collections;
import java.util.List;
public class AdapterFish extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private Context context;
final private Context context2 = context;
private LayoutInflater inflater;
List<DataFish> data= Collections.emptyList();
DataFish current;
int currentPos=0;
private final int VIEW_ITEM = 1;
private final int VIEW_PROG = 0;
// The minimum amount of items to have below your current scroll position before loading more.
private int visibleThreshold = 2;
private int lastVisibleItem, totalItemCount;
private boolean loading;
private OnLoadMoreListener onLoadMoreListener;
// create constructor to innitilize context and data sent from MainActivity
public AdapterFish(Context context, List<DataFish> data, RecyclerView recyclerView){
this.context=context;
inflater= LayoutInflater.from(context);
this.data=data;
if (recyclerView.getLayoutManager() instanceof LinearLayoutManager) {
final LinearLayoutManager linearLayoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();
recyclerView.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 (!loading && totalItemCount <= (lastVisibleItem + visibleThreshold)) {
// End has been reached
// Do something
if (onLoadMoreListener != null) {
onLoadMoreListener.onLoadMore();
}
loading = true;
}
}
});
}
}
@Override
public int getItemViewType(int position) {
return data.get(position) != null ? VIEW_ITEM : VIEW_PROG;
}
// Inflate the layout when viewholder created
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
MyViewHolder holder;
if (viewType == VIEW_ITEM) {
View view = inflater.inflate(R.layout.container_fish, parent, false);
holder = new MyViewHolder(view);
}
else
{
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.progressbar_item, parent, false);
RecyclerView.ViewHolder vh = new ProgressViewHolder(v);
return vh;
}
return holder;
}
// Bind data
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
// Get current position of item in recyclerview to bind data and assign values from list
MyViewHolder myHolder= (MyViewHolder) holder;
DataFish current=data.get(position);
myHolder.textFishName.setText(current.fishName);
myHolder.textSize.setText("Size: " + current.sizeName);
myHolder.textType.setText("Category: " + current.catName);
myHolder.textPrice.setText("Rs. " + current.price + "\\Kg");
myHolder.textPrice.setTextColor(ContextCompat.getColor(context, R.color.colorAccent));
// load image into imageview using glide
Glide.with(context).load("http://192.168.1.7/test/images/" + current.fishImage)
.placeholder(R.drawable.ic_img_error)
.error(R.drawable.ic_img_error)
.into(myHolder.ivFish);
}
public void setLoaded() {
loading = false;
}
// return total item from List
@Override
public int getItemCount() {
return data.size();
}
public void setOnLoadMoreListener(OnLoadMoreListener onLoadMoreListener) {
this.onLoadMoreListener = onLoadMoreListener;
}
public interface OnLoadMoreListener {
void onLoadMore();
}
public static class ProgressViewHolder extends RecyclerView.ViewHolder {
public ProgressBar progressBar;
public ProgressViewHolder(View v) {
super(v);
progressBar = (ProgressBar) v.findViewById(R.id.progressBar);
}
}
class MyViewHolder extends RecyclerView.ViewHolder{
TextView textFishName;
ImageView ivFish;
TextView textSize;
TextView textType;
TextView textPrice;
// create constructor to get widget reference
public MyViewHolder(View itemView) {
super(itemView);
textFishName= (TextView) itemView.findViewById(R.id.textFishName);
ivFish= (ImageView) itemView.findViewById(R.id.ivFish);
textSize = (TextView) itemView.findViewById(R.id.textSize);
textType = (TextView) itemView.findViewById(R.id.textType);
textPrice = (TextView) itemView.findViewById(R.id.textPrice);
}
}
}
答案 0 :(得分：1)
我可以提供自己的方法来加载更多项目。您必须创建一个名为ScrollRecycler的抽象类，它从RecyclerView.OnScrollListener扩展。这是实现
public abstract class ScrollRecycler extends RecyclerView.OnScrollListener {
int page = 0;
// The current offset index of data you have loaded
int startingPageIndex = 0;
// The total number of items in the dataset after the last load
private int previousTotalItemCount = 0;
// True if we are still waiting for the last set of data to load.
private boolean loading = true;
RecyclerView.LayoutManager mLayoutManager;
public ScrollRecycler(LinearLayoutManager layoutManager) {
this.mLayoutManager = layoutManager;
}
public int getLastVisibleItem(int[] lastVisibleItemPositions) {
int maxSize = 0;
for (int i = 0; i < lastVisibleItemPositions.length; i++) {
if (i == 0) {
maxSize = lastVisibleItemPositions[i];
}
else if (lastVisibleItemPositions[i] > maxSize) {
maxSize = lastVisibleItemPositions[i];
}
}
return maxSize;
}
// This happens many times a second during a scroll, so be wary of the code you place here.
// We are given a few useful parameters to help us work out if we need to load some more data,
// but first we check if we are waiting for the previous load to finish.
@Override
public void onScrolled(RecyclerView view, int dx, int dy) {
int lastVisibleItemPosition = 0;
int totalItemCount = mLayoutManager.getItemCount();
if (mLayoutManager instanceof StaggeredGridLayoutManager) {
int[] lastVisibleItemPositions = ((StaggeredGridLayoutManager) mLayoutManager).findLastVisibleItemPositions(null);
// get maximum element within the list
lastVisibleItemPosition = getLastVisibleItem(lastVisibleItemPositions);
} else if (mLayoutManager instanceof LinearLayoutManager) {
lastVisibleItemPosition = ((LinearLayoutManager) mLayoutManager).findLastVisibleItemPosition();
}
// If the total item count is zero and the previous isn't, assume the
// list is invalidated and should be reset back to initial state
if (totalItemCount < previousTotalItemCount) {
page = startingPageIndex;
this.previousTotalItemCount = totalItemCount;
if (totalItemCount == 0) {
this.loading = true;
}
}
// If it’s still loading, we check to see if the dataset count has
// changed, if so we conclude it has finished loading and update the current page
// number and total item count.
if (loading && (totalItemCount > previousTotalItemCount)) {
loading = false;
previousTotalItemCount = totalItemCount;
}
// If it isn’t currently loading, we check to see if we have breached
// the visibleThreshold and need to reload more data.
// If we do need to reload some more data, we execute onLoadMore to fetch the data.
// threshold should reflect how many total columns there are too
int visibleThreshold = 10;
if (!loading && (lastVisibleItemPosition + visibleThreshold) > totalItemCount) {
page++;
onLoadMore(page);
loading = true;
}
}
public abstract void onLoadMore(final int page);
您必须将您的抽象类添加到RecyclerView而不是Adapter。
public class MainActivity extends AppCompatActivity {
// CONNECTION_TIMEOUT and READ_TIMEOUT are in milliseconds
public static final int CONNECTION_TIMEOUT = 10000;
public static final int READ_TIMEOUT = 15000;
private RecyclerView mRVFishPrice;
private AdapterFish mAdapter;
protected Handler handler;
List<DataFish> data=new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Make call to AsyncTask
new AsyncLogin().execute();
handler = new Handler();
mRVFishPrice = (RecyclerView)findViewById(R.id.fishPriceList);
mAdapter = new AdapterFish(MainActivity.this, data, mRVFishPrice);
mRVFishPrice.setAdapter(mAdapter);
mRVFishPrice.setLayoutManager(new LinearLayoutManager(MainActivity.this));
mRVFishPrice.addOnScrollListener(new ScrollRecycler(new LinearLayoutManager(MainActivity.this)) {
@Override
public void onLoadMore(int page) {
// you can make network call to Server in order to retrive data here page is comminh
}
});
}
我认为它会对你有所帮助
答案 1 :(得分：0)
这是我的Fragment代码
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
view = inflater.inflate(R.layout.fragment_all, container, false);
ButterKnife.bind(this, view);
fab = (FloatingActionButton) view.findViewById(R.id.fab_fragment_all);
type = getArguments().getString("type");
if(type.equals(Utils.TYPE_JOURNAL)){
fab.show();
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
makeSubscribeForJournal();
}
});
}else{
fab.hide();
}
category_name = getArguments().getString("category_name");
manager = new LinearLayoutManager(getContext());
adapter = new AllAdapter(getContext(), onArticleClickListener);
recyclerView.setLayoutManager(manager);
recyclerView.setAdapter(adapter);
swipe.post(new Runnable() {
@Override
public void run() {
swipe.setRefreshing(true);
makeCall(1, category_name,type);
}
});
swipe.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
swipe.setRefreshing(false);
}
});
recyclerView.addOnScrollListener(new ScrollRecycler(manager, type) {
@Override
public void onLoadMore(int page) {
makeCall(page, category_name,type);
}
});
return view;
}
这是我的ScrollRecycler抽象类，它与你的相同。
public abstract class ScrollRecycler extends RecyclerView.OnScrollListener {
int page = 1;
// The current offset index of data you have loaded
int startingPageIndex = 0;
// The total number of items in the dataset after the last load
private int previousTotalItemCount = 0;
// True if we are still waiting for the last set of data to load.
private boolean loading = true;
String type;
RecyclerView.LayoutManager mLayoutManager;
public ScrollRecycler(LinearLayoutManager layoutManager ,String type) {
this.mLayoutManager = layoutManager;
this.type= type;
}
public int getLastVisibleItem(int[] lastVisibleItemPositions) {
int maxSize = 0;
for (int i = 0; i < lastVisibleItemPositions.length; i++) {
if (i == 0) {
maxSize = lastVisibleItemPositions[i];
}
else if (lastVisibleItemPositions[i] > maxSize) {
maxSize = lastVisibleItemPositions[i];
}
}
return maxSize;
}
// This happens many times a second during a scroll, so be wary of the code you place here.
// We are given a few useful parameters to help us work out if we need to load some more data,
// but first we check if we are waiting for the previous load to finish.
@Override
public void onScrolled(RecyclerView view, int dx, int dy) {
int lastVisibleItemPosition = 0;
int totalItemCount = mLayoutManager.getItemCount();
if(type.equals(Utils.TYPE_JOURNAL)) {
if (dy > 0) {
AllFragment.fab.hide();
} else {
AllFragment.fab.show();
}
}
if (mLayoutManager instanceof StaggeredGridLayoutManager) {
int[] lastVisibleItemPositions = ((StaggeredGridLayoutManager) mLayoutManager).findLastVisibleItemPositions(null);
// get maximum element within the list
lastVisibleItemPosition = getLastVisibleItem(lastVisibleItemPositions);
} else if (mLayoutManager instanceof LinearLayoutManager) {
lastVisibleItemPosition = ((LinearLayoutManager) mLayoutManager).findLastVisibleItemPosition();
}
// If the total item count is zero and the previous isn't, assume the
// list is invalidated and should be reset back to initial state
if (totalItemCount < previousTotalItemCount) {
page = startingPageIndex;
this.previousTotalItemCount = totalItemCount;
if (totalItemCount == 0) {
this.loading = true;
}
}
// If it’s still loading, we check to see if the dataset count has
// changed, if so we conclude it has finished loading and update the current page
// number and total item count.
if (loading && (totalItemCount > previousTotalItemCount)) {
loading = false;
previousTotalItemCount = totalItemCount;
}
// If it isn’t currently loading, we check to see if we have breached
// the visibleThreshold and need to reload more data.
// If we do need to reload some more data, we execute onLoadMore to fetch the data.
// threshold should reflect how many total columns there are too
int visibleThreshold = 10;
if (!loading && (lastVisibleItemPosition + visibleThreshold) > totalItemCount) {
page++;
onLoadMore(page);
loading = true;
}
}
public abstract void onLoadMore(final int page);
}