我正在尝试创建带有使用图像适配器创建的图像库的Android应用程序，该图像适配器使用毕加索库获取数据。但是没有显示图像。这可能是上下文问题或者毕加索库但我不知道在哪里这是问题因为我没有得到任何错误。根据Logs
，一切正常**package com.example.android.popmovies;
import android.content.Context;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
import com.squareup.picasso.Picasso;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
/**
* A placeholder fragment containing a simple view.
*/
public class PopMovieFragment extends Fragment {
ImageAdapter imageAdapter;
public PopMovieFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_main,container,false);
GridView gridView = (GridView) view.findViewById(R.id.gridview);
imageAdapter = new ImageAdapter(getActivity(),new ArrayList<String>());
gridView.setAdapter(imageAdapter);
gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Log.v("check","ok");
}
});
return inflater.inflate(R.layout.fragment_main, container, false);
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public void onStart() {
super.onStart();
updateMovies();
}
public void updateMovies() {
FetchMovieTask movieTask = new FetchMovieTask();
movieTask.execute();
}
public class FetchMovieTask extends AsyncTask<String, Void, String[]> {
final String LOG_TAG = FetchMovieTask.class.getSimpleName();
private String[] getMovieImageFromJson(String movieJsonStr)
throws JSONException {
ArrayList<String> movieResults = new ArrayList<>();
String posterUrl;
final String OWM_MOVIE_RESULTS = "results";
JSONObject jsonObject = new JSONObject(movieJsonStr);
if (jsonObject.has(OWM_MOVIE_RESULTS)) {
JSONArray movieArray = jsonObject.getJSONArray(OWM_MOVIE_RESULTS);
//JSONArray movieArray = jsonObject.getJSONArray(OWM_MOVIE_RESULTS);
for (int i = 0; i < movieArray.length(); i++) {
JSONObject movieObject = movieArray.getJSONObject(i);
posterUrl = movieObject.getString("poster_path");
movieResults.add(posterUrl);
Log.v(LOG_TAG, posterUrl);
}
for (String items : movieResults){
Log.v(LOG_TAG,items);
}
// return null;
}
return movieResults.toArray(new String[0]);
// Log.v(LOG_TAG,posterUrl);
}
@Override
protected String[] doInBackground(String... params) {
HttpURLConnection urlConnection = null;
BufferedReader reader = null;
String movieJsonStr = null;
//parameters for api link will be here
try {
final String MOVIE_BASE_URL = "https://api.themoviedb.org/3/movie";
final String APPID_PARAM = "api_key";
final String CRITERIA_FOR_MOVIE_SELECTION_TOP = "top_rated";
final String CRITERIA_FOR_MOVIE_SELECTION_POPULAR = "popular";
Uri builtUri = Uri.parse(MOVIE_BASE_URL).buildUpon()
.appendPath(CRITERIA_FOR_MOVIE_SELECTION_TOP)
.appendQueryParameter(APPID_PARAM, BuildConfig.OPEN_MOVIEDB_API_KEY)
.build();
Log.v("TAG","BuiltURI" + builtUri.toString());
URL url = new URL(builtUri.toString());
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.connect();
// Read input stream into a String
InputStream inputstream = urlConnection.getInputStream();
StringBuffer buffer = new StringBuffer();
if (inputstream == null) {
movieJsonStr = null;
}
reader = new BufferedReader(new InputStreamReader(inputstream));
String line;
while ((line = reader.readLine()) != null) {
buffer.append(line + "\n");
}
if (buffer.length() == 0) {
movieJsonStr = null;
}
movieJsonStr = buffer.toString();
Log.v(LOG_TAG, "Movie Json String" + movieJsonStr);
} catch (IOException e) {
Log.e(LOG_TAG, "error here" + e);
movieJsonStr = null;
} finally {
if (urlConnection != null) {
urlConnection.disconnect();
}
if (reader != null) {
try {
reader.close();
} catch (final IOException e) {
Log.e(LOG_TAG, "ErrorClosingStream", e);
}
}
}
try {
// here will be method call for JSon parsing.
String [] check_items = getMovieImageFromJson(movieJsonStr);
for (String items : check_items){
Log.v(LOG_TAG,items+"new");
}
return check_items;
} catch (JSONException e) {
Log.e(LOG_TAG, e.getMessage(), e);
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(String[] result) {
if (result != null) {
for (String resultItems : result){
Log.v(LOG_TAG,resultItems+"GoodLuck");
final String PICTURE_BASE_URL = "http://image.tmdb.org/t/p/w185/";
final String PICTURE_URL_END = resultItems;
Uri builtUri = Uri.parse(PICTURE_BASE_URL).buildUpon()
.appendPath(PICTURE_URL_END.replace("/",""))
.build();
Log.v(LOG_TAG,resultItems+"GoodLuck"+builtUri.toString());
imageAdapter.setmresultItems(builtUri.toString());
}
}
}
}
}
class ImageAdapter extends BaseAdapter {
private Context mContext;
private ArrayList<String> mresultItems;
public ImageAdapter(Context c,ArrayList<String> resultItems){
mContext = c;
mresultItems = resultItems;
}
public int getCount(){
// return mThumbsIds.length;
return 0;
}
public Object getItem(int position){
return null;
}
public long getItemId(int position){
return 0;
}
public void setmresultItems(String resultItems){
mresultItems.add(resultItems);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView;
if (convertView == null){
// if it is not recycled, initialize some attributes
imageView = new ImageView(mContext);
imageView.setLayoutParams(new GridView.LayoutParams(85,85));
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
imageView.setPadding(8,8,8,8);
}else{
imageView = (ImageView) convertView;
}
//imageView.setImageResource(mThumbsIds[position]);
for(String picResultUrl : mresultItems){
Picasso.with(mContext).load(picResultUrl).into(imageView);
}
return imageView;
}
//references to our Images
//private Integer[] mThumbsIds ;
}**
答案 0 :(得分：1)
你不应该在getView（）方法中有一个for循环，它已经为列表中的每个项调用了。
请务必返回正确的计数：
public int getCount(){
return mresultItems.size();
}
然后，在getView（）中只使用数据源的当前位置：
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView;
if (convertView == null){
imageView = new ImageView(mContext);
imageView.setLayoutParams(new GridView.LayoutParams(85,85));
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
imageView.setPadding(8,8,8,8);
}else{
imageView = (ImageView) convertView;
}
//modified:
String picUrl = mresultItems.get(position);
Picasso.with(mContext).load(picUrl).into(imageView);
}
return imageView;
}
此外，在适配器的数据源更新后，在notifyDataSetChanged()中调用适配器上的onPostExecute()：
@Override
protected void onPostExecute(String[] result) {
if (result != null) {
for (String resultItems : result){
Log.v(LOG_TAG,resultItems+"GoodLuck");
final String PICTURE_BASE_URL = "http://image.tmdb.org/t/p/w185/";
final String PICTURE_URL_END = resultItems;
Uri builtUri = Uri.parse(PICTURE_BASE_URL).buildUpon()
.appendPath(PICTURE_URL_END.replace("/",""))
.build();
Log.v(LOG_TAG,resultItems+"GoodLuck"+builtUri.toString());
imageAdapter.setmresultItems(builtUri.toString());
}
//Add this here:
imageAdapter.notifyDataSetChanged();
}
}
答案 1 :(得分：0)
我发现我没有在onCreate方法中返回视图，这是空白屏幕的根本原因。