按下搜索按钮后未显示的图像列表

Question

我正在使用谷歌图片搜索API获取图片网址。我使用okhttp连接到网址。这是在我的activity的oncreate方法中完成的。在片段的oncreate（）方法中我获取所有图像URL并将它们存储在mSmallIMagesUrl中，在oncreateView（）中我尝试使用自定义适配器显示图像。但是当我运行我的应用程序时，点击搜索按钮，它显示一个空白页面，当我返回并单击搜索按钮（搜索框中始终有文本）时，它会显示上一个搜索文本的图像。我不知道为什么会这样，下面是我的代码，请让我知道我错过了什么。谢谢

package com.paveynganpi.allsearch;

import android.content.Context;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.support.annotation.Nullable;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;
import android.widget.AbsListView;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.GridView;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import com.squareup.okhttp.Call;
import com.squareup.okhttp.Callback;
import com.squareup.okhttp.OkHttpClient;
import com.squareup.okhttp.Request;
import com.squareup.okhttp.Response;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import org.w3c.dom.Text;

import java.io.IOException;
import java.util.ArrayList;


public class ImageGrid extends ActionBarActivity {

private static final String TAG = ImageGrid.class.getSimpleName();

protected int start = 0;//variable to change pages from google Api

//contains extra images urls to supply to ... when need
protected  static ArrayList<ArrayList<String>> mBigImagesUrls = new ArrayList<ArrayList<String>>();
//contains image urls to inject into gridview
protected static  ArrayList<String> mSmalImagesUrls = new ArrayList<>();

protected static String mEditedString;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_image_grid);
    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
                .add(R.id.container, new PlaceholderFragment())
                .commit();
    }


   for (int start = 0; start < 2; start++) {


        if (isNetworkAvailable()) {

            //using okHttp library to connect to imagesUrl and retrieve JSON Data
            OkHttpClient client = new OkHttpClient();
            Request request = new Request.Builder()
                    .url(getImagePage(start)).
                            build();

            Call call = client.newCall(request);

            //runs the below code asynchronously
            call.enqueue(new Callback() {
                @Override
                public void onFailure(Request request, IOException e) {
                    Log.v(TAG, "error from request");

                }

                @Override
                public void onResponse(Response response) throws IOException {

                    try {
                        String jsonData = response.body().string();
                        //Log.v(TAG, jsonData);

                        if (!response.isSuccessful()) {
                            alertUserAboutError();
                        } else {

                           // mSmalImagesUrls = getCurrentDetails(jsonData);
                            mBigImagesUrls.add(getCurrentDetails(jsonData));
                            Log.d(TAG, mBigImagesUrls.size() + " big size");
                            Log.d(TAG, mSmalImagesUrls.size() + " small size");

                        }
                    } catch (IOException | JSONException e) {
                        Log.e(TAG, "Exception caught :", e);
                    }
                }
            });
        } else {
            Toast.makeText(this, "Network is unavailable", Toast.LENGTH_LONG).show();
        }
    }
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_image_grid, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}


private String getImagePage(int start) {
    return "https://ajax.googleapis.com/ajax/services/search/images?v=1.0&q="
            + mEditedString + "&rsz=8&start=" + start;
}

//get data
private ArrayList<String> getCurrentDetails(String jsonData) throws JSONException {

    JSONObject jsonObject = new JSONObject(jsonData);
    JSONObject responseData = jsonObject.getJSONObject("responseData");

    ArrayList<String> localList = new ArrayList<String>();

    JSONArray results = responseData.getJSONArray("results");


    for (int i = 0; i < results.length(); i++) {

        localList.add(results.getJSONObject(i).getString("url"));

    }

    return localList;

}

//An AlertDialog to display to user when an error occurs
private void alertUserAboutError() {

    AlertDialogFragment dialog = new AlertDialogFragment();
    dialog.show(getFragmentManager(), "error_dialog");


}

//checks if user is connected to a network
private boolean isNetworkAvailable() {

    ConnectivityManager cm =
            (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);

    NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
    boolean isAvailable = false;

    if (activeNetwork != null && activeNetwork.isConnectedOrConnecting()) {
        isAvailable = true;
    }
    return isAvailable;


}

@Override
public void onBackPressed() {
    super.onBackPressed();

    Log.d(TAG,"back was pressed");
    mBigImagesUrls.clear();
    mSmalImagesUrls.clear();


}

/**
 * A placeholder fragment containing a simple view.
 */
public static class PlaceholderFragment extends Fragment {

    protected GridView mGridView;//reference to gridview in fragment_image_grid.xml

static String mEditedString;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        Log.d(TAG, mBigImagesUrls.size() + " final big size");
        Log.d(TAG, mSmalImagesUrls.size() + "final small size");


        for(int i =0;i<mBigImagesUrls.size();i++){

            for(int j =0;j<8;j++){

                mSmalImagesUrls.add(mBigImagesUrls.get(i).get(j));

            }

        }

    }

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        final View rootView = inflater.inflate(R.layout.fragment_image_grid, container, false);

        final ArrayList<String> testList = new ArrayList<String>();

        //gets the edited string from MainActivity
        Bundle args = getActivity().getIntent().getExtras();
        mEditedString = args.getString("space");

        mGridView = (GridView)rootView.findViewById(R.id.imagesGrid);//reference to gridview
        ImagesGridAdapter adapter = new ImagesGridAdapter(getActivity(), mSmalImagesUrls);
        mGridView.setAdapter(adapter);


        return rootView;
    }



}

}

Answer 1

由于您正在发出异步请求，因此响应无法立即生效。您可以在下载图像列表时显示ProgressBar，然后在完成下载后显示列表。

之后，通知适配器数据集已更改。