android - 如何在 Android 中使用 JSON 在 ListView 中获取 YouTube 缩略图？到目前为止我的代码是:

Question

尝试获取有关如何使用下面代码中提到的网址中的所有标签的信息。

公共(public)类 YoutubeVideoMain 扩展了 Activity {

ListView videolist;

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

ArrayAdapter<String> videoadapter;
Context context;

String feedURL = "https://gdata.youtube.com/feeds/api/users/twistedequations/uploads?v=2&alt=jsonc&start-index=1&max-results=5";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    context = this;
    setContentView(R.layout.youtubelist);
    videolist = (ListView) findViewById(R.id.videolist);

    videoadapter = new ArrayAdapter<String>(this, R.layout.video_list_item,
            videoArrayList);

    videolist.setAdapter(videoadapter);
    VideoListTask loadertask = new VideoListTask();
    loadertask.execute();
}

private class VideoListTask extends AsyncTask<Void, String, Void> {

    ProgressDialog dialogue;

    @Override
    protected void onPostExecute(Void result) {
        super.onPostExecute(result);
        dialogue.dismiss();

        videoadapter.notifyDataSetChanged();
    }

    @Override
    protected void onPreExecute() {
        dialogue = new ProgressDialog(context);

        dialogue.setTitle("Loading items..");
        dialogue.show();
        super.onPreExecute();

    }

    @Override
    protected Void doInBackground(Void... params) {

        HttpClient client = new DefaultHttpClient();
        HttpGet getRequest = new HttpGet(feedURL);
        try {
            HttpResponse response = client.execute(getRequest);
            StatusLine statusline = response.getStatusLine();
            int statuscode = statusline.getStatusCode();

            if (statuscode != 200) {

                return null;
            }

            InputStream jsonStream = response.getEntity().getContent();

            BufferedReader reader = new BufferedReader(
                    new InputStreamReader(jsonStream));

            StringBuilder builder = new StringBuilder();
            String line;

            while ((line = reader.readLine()) != null) {

                builder.append(line);

            }
            String jsonData = builder.toString();

            JSONObject json = new JSONObject(jsonData);

            JSONObject data = json.getJSONObject("data");

            JSONArray items = data.getJSONArray("items");

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

                JSONObject video = items.getJSONObject(i);

                videoArrayList.add(video.getString("title"));

            }

            Log.i("YouJsonData:", jsonData);

        } catch (ClientProtocolException e) {

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

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

            e.printStackTrace();
        }

        return null;
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

}

我正在尝试在 ListView 中获取缩略图，并尝试在单击任何项​​目时打开新的视频播放器。上面的代码显示带有视频标题的项目列表，但我也想向其中添加缩略图。

帮我解决这个问题。

Answer 1

我使用 Universal ImageL0ader 进行延迟加载。您下载相同的内容并使用它或使用不同的技术。根据您的需要自定义以下内容。

1. 使用线程或Asynctask向json响应发出http请求。

2. 解析响应并将其存储在列表中。

3. 使用自定义适配器来显示数据。

您还可以使用 Volley 库。

public class MainActivity extends Activity {

    Button b;
    ListView lv;
    ArrayList<String> msg = new ArrayList<String>();
    ArrayList<String> title = new ArrayList<String>();
    ArrayList<String> thumb = new ArrayList<String>();
    ProgressDialog pd;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        lv= (ListView) findViewById(R.id.lv);
        pd = new ProgressDialog(MainActivity.this);
        pd.setTitle("Loading..");
        b= (Button) findViewById(R.id.button1);
        b.setOnClickListener(new OnClickListener()
        {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                new TheTask().execute();
            }

       });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
    public void getData()
    {
        HttpClient httpclient = new DefaultHttpClient();
        httpclient.getParams().setParameter(CoreProtocolPNames.PROTOCOL_VERSION, HttpVersion.HTTP_1_1);
        HttpGet request = new HttpGet("https://gdata.youtube.com/feeds/api/users/twistedequations/uploads?v=2&alt=jsonc&start-index=1&max-results=5");

        try
        {
        HttpResponse response = httpclient.execute(request);
        HttpEntity resEntity = response.getEntity();
        String _response=EntityUtils.toString(resEntity); // content will be consume only once

        JSONObject json = new JSONObject(_response);

        JSONArray jsonArray = json.getJSONObject("data").getJSONArray("items");
        for (int i = 0; i < jsonArray.length(); i++) {
            JSONObject jsonObject = jsonArray.getJSONObject(i);

            String title1 = jsonObject.getString("title");
            title.add(title1);
            String thumbUrl = jsonObject.getJSONObject("thumbnail").getString("sqDefault");
            URL url1 = new URL(thumbUrl);
            //Bitmap bmp = BitmapFactory.decodeStream(url1.openConnection().getInputStream());
            thumb.add(thumbUrl);
            String url;
            try {

                url = jsonObject.getJSONObject("player").getString("default");
                msg.add(url);
            } catch (JSONException ignore) {
            }
        }
        } 
        catch(Exception e1)
            {
                e1.printStackTrace();
            }

        httpclient.getConnectionManager().shutdown();
    }
  class TheTask extends AsyncTask<Void,Void,Void>
  {

    @Override
    protected void onPostExecute(Void result) {
        // TODO Auto-generated method stub
        super.onPostExecute(result);
        pd.dismiss();
        YouTubeAdapter you = new YouTubeAdapter(MainActivity.this,msg,title,thumb);
        lv.setAdapter(you);
    }

    @Override
    protected void onPreExecute() {
        // TODO Auto-generated method stub
        super.onPreExecute();
        pd.show();
    }

    @Override
    protected Void doInBackground(Void... params) {
        // TODO Auto-generated method stub
        getData();
        return null;
    }

  }
}

public class YouTubeAdapter extends BaseAdapter{

    Context mContext;
    Intent intent;
    LayoutInflater mInflater;
    ArrayList<String> mVideo;
    ArrayList<String> mTitle;
    ArrayList<String> mThumb;
    static DisplayImageOptions options;
    static ImageLoader imageLoader;

    public YouTubeAdapter(Context context,ArrayList<String> a,ArrayList<String> title,ArrayList<String> thumb)  {
        mContext=context;
        mVideo=a;   
        mTitle = title;
        mThumb= thumb;
         options = new DisplayImageOptions.Builder()
         .showImageForEmptyUri(R.drawable.ic_launcher)
         .resetViewBeforeLoading()
         .cacheOnDisc()
         .imageScaleType(ImageScaleType.IN_SAMPLE_INT)
         .bitmapConfig(Bitmap.Config.RGB_565)
         .displayer(new FadeInBitmapDisplayer(300))
         .build();

        imageLoader = ImageLoader.getInstance();
        imageLoader.init(ImageLoaderConfiguration.createDefault(context));
        mInflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        return mVideo.size();
    }

    @Override
    public Object getItem(int position) {
        // TODO Auto-generated method stub
        return position;
    }

    @Override
    public long getItemId(int position) {
        // TODO Auto-generated method stub
        return position;
    }

    @Override
    public View getView(final int position, View arg1, ViewGroup arg2) {
        ViewHolder vh;

        if(arg1==null)
        {
            arg1=mInflater.inflate(R.layout.video, null);
            vh= new ViewHolder();
            vh.tv1=(TextView)arg1.findViewById(R.id.textView1);
            vh.tv2=(TextView)arg1.findViewById(R.id.textView2);
            vh.iv=(ImageView)arg1.findViewById(R.id.imageView1);
            vh.pb = (ProgressBar) arg1.findViewById(R.id.pb);
            arg1.setTag(vh);
        }
        else
        {
            vh= (ViewHolder)arg1.getTag();
        }
        vh.tv1.setText(mTitle.get(position));
        vh.tv2.setText(mVideo.get(position));
        display(vh.iv, mThumb.get(position), vh.pb); 
        return arg1;
    }

    static  public void display(ImageView img, String url, final ProgressBar spinner)
    {
        imageLoader.displayImage(url, img, options, new ImageLoadingListener() {
            @Override
            public void onLoadingStarted(String imageUri, View view) {
             spinner.setVisibility(View.VISIBLE);
            }
            @Override
            public void onLoadingFailed(String imageUri, View view, FailReason failReason) {
             spinner.setVisibility(View.GONE);


            }
            @Override
            public void onLoadingComplete(String imageUri, View view, Bitmap loadedImage) {
             spinner.setVisibility(View.GONE);
            }
            @Override
            public void onLoadingCancelled(String imageUri, View view) {

            }

    });
    }
    static class ViewHolder
    {
        TextView tv1;
        TextView tv2;
        ImageView iv;
        ProgressBar pb;
    }
}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <ListView
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:id="@+id/lv"
        android:layout_above="@+id/button1"
       />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:text="Button" />

</RelativeLayout>

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