使用不同的起始编号从 google 图片搜索 api 中获取 json 数据

Question

google 图片搜索 url 看起来像这样 https://ajax.googleapis.com/ajax/services/search/images?v=1.0&q=eden%20hazard&rsz=8&start=4 其中每页最大图片中的 rsz 参数和起始参数是页码。我能够在页面中获取所有图像。但是对于说 20 页，即 start= 0 ... 19，我不知道这样做。我下面的代码显示了我是如何从页面中获取图像的。请让我知道如何让它获取多页图像。我尝试在我的异步任务（okhttp enqueue）之外使用 for 循环。

 package com.paveynganpi.allsearch;

 import android.content.Context;
 import android.content.Intent;
 import android.net.ConnectivityManager;
 import android.net.NetworkInfo;
 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();

@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();
    }



}

@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);
}


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

    protected GridView mGridView;//reference to gridview in fragment_image_grid.xml
    protected int start = 0;//variable to change pages from google Api

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

    protected static String mEditedString;


    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");

        String imagesUrl = "https://ajax.googleapis.com/ajax/services/search/images?v=1.0&q="
                + mEditedString +"&rsz=8&start=" + start;


        //populate(start,imagesUrl.substring(0,imagesUrl.length()-1));

        if(isNetworkAvailable()) {

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

                            getActivity().runOnUiThread(new Runnable(){
                                @Override
                                public void run(){
                                    mGridView =(GridView) rootView.findViewById(R.id.imagesGrid);//reference to gridview
                                    ImagesGridAdapter adapter = new ImagesGridAdapter(getActivity(),mSmalImagesUrls);
                                    mGridView.setAdapter(adapter);
                                }
                            });


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

        return rootView;
    }

    //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(getActivity().getFragmentManager(),"error_dialog");


    }

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

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

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

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


    }

}

}

Answer 1

您可以创建如下方法：

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

}

然后：

for (start=0;start<20;start++){

 if(isNetworkAvailable()) {

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

                        getActivity().runOnUiThread(new Runnable(){
                            @Override
                            public void run(){
                                mGridView =(GridView) rootView.findViewById(R.id.imagesGrid);//reference to gridview
                                ImagesGridAdapter adapter = new ImagesGridAdapter(getActivity(),mSmalImagesUrls);
                                mGridView.setAdapter(adapter);
                            }
                        });


                    }
 ...
}

我建议您只使用连接逻辑创建一个方法。此代码将下载 20 页内容并在每次请求完成时更新您的 gridView。因此，最后，您将拥有包含最后一页内容的 gridView。要只存储页面的内容，请创建一个 HashMap<Integer,List<String>> 来存储每个页面的 url。

使用不同的起始编号从 google 图片搜索 api 中获取 json 数据

getting json data from google image search api with different start numbers

android

json

android-asynctask

google-image-search

okhttp