Question

您好我有一个下载程序类，用于处理我的应用程序中的下载，该类带有上下文。我在我的片段中使用了这个下载程序类，但我不知道在我的片段中新的mDownloader(????, urlAddress, rv, swipeRefreshLayout).execute();中为上下文传递了什么。当我通过getAcitivity()

时，它会给我一个错误

HomeFragment.java

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.widget.SwipeRefreshLayout;
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 com.zoggfrombetelgeuse.closet.MySQL.mDownloader;


public class HomeFragment extends Fragment {

public HomeFragment() {
    // Required empty public constructor
}





static String urlAddress = "http://localhost/my-site/dbGet.php";

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View view = inflater.inflate(R.layout.fragment_home, container, false);
    final RecyclerView rv = (RecyclerView) view.findViewById(R.id.card_view);
    rv.setLayoutManager(new LinearLayoutManager(getActivity()));

    final SwipeRefreshLayout swipeRefreshLayout = (SwipeRefreshLayout) view.findViewById(R.id.swipe_layout);
    return view;

    swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {

        @Override
        public void onRefresh() {
            new mDownloader(????, urlAddress, rv, swipeRefreshLayout).execute();
        }
    });






}


}

mDownloader.java

import android.content.Context;
import android.os.AsyncTask;
import android.support.v4.widget.SwipeRefreshLayout;
import android.support.v7.widget.RecyclerView;
import android.widget.Toast;

import com.zoggfrombetelgeuse.closet.HomeFragment;

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.sql.Connection;


public class mDownloader extends AsyncTask<Void, Void, String> {

Context c;
String urlAddress;
RecyclerView rv;

public mDownloader(Context c, String urlAddress, RecyclerView rv, SwipeRefreshLayout swipeRefreshLayout) {
    this.c  = c;
    this.urlAddress = urlAddress;
    this.rv = rv;
    this.swipeRefreshLayout = swipeRefreshLayout;
}

SwipeRefreshLayout swipeRefreshLayout;

@Override
protected void onPreExecute() {

    if (!swipeRefreshLayout.isRefreshing()){

        swipeRefreshLayout.setRefreshing(true);

    }
}

@Override
protected String doInBackground(Void... voids) {
    return this.downloadData();
}

@Override
protected void onPostExecute(String jsonData) {
    super.onPostExecute(jsonData);

    if (jsonData == null){

        swipeRefreshLayout.setRefreshing(false);
        Toast.makeText(c, "Unable to refresh feed", Toast.LENGTH_SHORT).show();
    }
    else {
        new mDataParser(c,jsonData,rv,swipeRefreshLayout).execute();
    }
}



private String downloadData() {

HttpURLConnection con = mConnector.connect(urlAddress);
if (con == null) {

    return null;
}

try {

    InputStream inputStream = new BufferedInputStream(con.getInputStream());
    BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));

    String line;
    StringBuffer jsonData = new StringBuffer();

    while ((line = bufferedReader.readLine()) != null) ;
    {
        jsonData.append(line + "\n");
    }

    bufferedReader.close();
    inputStream.close();
    return jsonData.toString();

} catch (IOException e) {
    e.printStackTrace();
}

return null;
}}

在片段中传递上下文

0 个答案: