我们知道每个 YouTube 视频都有一张图片。我们可以使用 jsonc 文件获取该图像的来源。我编写了一个代码来获取该图像的来源，然后将其存储在一个字符串中，以便使用位图将其放入我的服装列表视图中的图像视图中。在解析中我没有问题我可以存储图像的来源。但是当我的服装视图显示时，图像并没有出现在其中。我被告知从网络获取图像是非常非常糟糕的事情，不要在 UI 线程上进行网络调用。我应该而且必须使用一些库来管理和缓存位图。我能做些什么来解决这个问题？
这是我从 jsonc 文件进行解析的主要活动：
import java.util.ArrayList;
import java.util.Collection;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.impl.conn.DefaultClientConnection;
import org.apache.http.protocol.HTTP;
import org.apache.http.util.EntityUtils;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import org.json.JSONTokener;
import com.example.tstnetconnwithjson.tables.custome;
import com.example.tstnetconnwithjson.tables.videos;
import android.os.AsyncTask;
import android.os.Bundle;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.AlertDialog.Builder;
import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;
public class MainActivity extends Activity {
Button search; ;
TextView name ;
ListView listview ;
ArrayList<videos > videolist;
ArrayAdapter< videos > adapter ;
AlertDialog.Builder alert ;
ProgressDialog progressdialog ;
EditText name;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
videolist = new ArrayList<videos>();
adapter = new ArrayAdapter<videos>(this, android.R.layout.simple_list_item_1 , android.R.id.text1,videolist);
name=(EditText) findViewById(R.id.editText1);
alert = new Builder(this);
alert.setTitle("Warnning" ) ;
alert.setMessage("You want to connect to the internet ..? " );
alert.setNegativeButton("No ", null);
alert.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface arg0, int arg1) {
String username=name.getText().toString();
new connection().execute("https://gdata.youtube.com/feeds/api/videos?author="+username+"&v=2&alt=jsonc");
}
});
progressdialog = new ProgressDialog(this);
progressdialog.setMessage("Wait Loading .... ");
progressdialog.setCancelable(false);
search = (Button) findViewById(R.id.button1);
name = (TextView) findViewById(R.id.textView1);
listview = (ListView) findViewById(R.id.listView1);
listview.setAdapter(adapter);
search.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
alert.show();
}
});
}
class connection extends AsyncTask<String, Integer, String>{
@Override
protected void onPreExecute() {
progressdialog.show();
super.onPreExecute();
}
@Override
protected String doInBackground(String... arg0) {
String s = GetUrlBody(arg0[0]);
return s;
}
@Override
protected void onPostExecute(String result) {
try{
JSONObject jo =(JSONObject) new JSONTokener(result).nextValue();
JSONObject feed = jo.optJSONObject("data");
JSONArray entry = feed.optJSONArray("items");
for(int i = 0 ; i<entry.length() ; i++){
String title = entry.getJSONObject(i).getString("title");
String thumbURL = entry.getJSONObject(i).getJSONObject("thumbnail").getString("sqDefault");
Log.d("after get image", "ok")
String url;
try {
url = entry.getJSONObject(i).getJSONObject("player").getString("mobile");
} catch (JSONException ignore) {
url = entry.getJSONObject(i).getJSONObject("player").getString("default");
}
String description = entry.getJSONObject(i).getString("description");
Log.d("after get description", "ok");
videos videoobject=new videos();
videoobject.setDecscrption(description);
videoobject.setImageurl(thumbURL);
videoobject.setVediourl(url);
videoobject.setVideoname(title);
videolist.add(videoobject);
}
listview.setAdapter(new custome(MainActivity.this,videolist));
Log.d("AFTER set custome ", "before notify changes");
adapter.notifyDataSetChanged();
}catch(Exception exception) {
Log.d("exception ", "nock nock nock....");
Log.e("json ", exception.getMessage());
}
progressdialog.dismiss();
super.onPostExecute(result);
}
String GetUrlBody (String Url ){
HttpClient client = new DefaultHttpClient();
HttpGet gethttp = new HttpGet(Url);
try{
HttpResponse response = client.execute(gethttp);
if(response.getStatusLine().getStatusCode() == 200){
String save =
EntityUtils.toString(response.getEntity(), HTTP.UTF_8);
return save;
}else {
return "Not Found";
}
}catch(Exception exception){}
return null;
}
}
}
这是我的服装列表视图：
public class custome extends BaseAdapter {
ArrayList<videos> data=new ArrayList<videos>();
android.content.Context context1;
android.widget.TextView name;
ImageView picture;
public custome(Context context,ArrayList<videos>arrayList) {
// TODO Auto-generated constructor stub
context1=context;
data= arrayList;
}
public int getCount() {
// TODO Auto-generated method stub
return data.size();
}
public Object getItem(int arg0) {
// TODO Auto-generated method stub
return data.get(arg0);
}
public long getItemId(int arg0) {
// TODO Auto-generated method stub
return arg0;
}
public View getView(int arg0, View arg1, ViewGroup arg2) {
View view=arg1;
if(view==null)
{
LayoutInflater layoutInflater=(LayoutInflater) _c.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
view=layoutInflater.inflate(R.layout.listvideo,null);
}
name=(TextView) view.findViewById(R.id.textView1);
picture=(ImageView) view.findViewById(R.id.imageView1);
videos video = data.get(arg0);
name.setText(video.getVideoname());
URL url = null;
try {
url = new URL(video.getImageurl());
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Bitmap bitmap = null;
try {
bitmap = BitmapFactory.decodeStream(url.openConnection().getInputStream());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
picture.setImageBitmap(bitmap);
return view;
}
}