我正在尝试将处理位图的谷歌示例 BitmapFun 改编为我自己的代码。我通过异步任务（SearchDaMovies）通过 JSON 从 mysql 数据库中获取图片 url。问题是，我无法将图片加载到图像适配器中。它适用于示例数组“imageThumbUrls”。但是当我用我需要的字符串数组“arrayS”替换“imageThumbUrls”字符串数组时，它给了我一个 NullPointerException。我该怎么做？我已经坚持了一周。
public class ImageGridFragment extends Fragment implements AdapterView.OnItemClickListener {
private static final String TAG = "ImageGridFragment";
private static final String IMAGE_CACHE_DIR = "thumbs";
private int mImageThumbSize;
private int mImageThumbSpacing;
private ImageAdapter mAdapter;
private ImageFetcher mImageFetcher;
String id, name, year, genre, known, tag1, tag2, tag3, poster, oster, description, vote ;
private ProgressDialog pDialog;
jParser parser = new jParser();
ArrayList<HashMap<String, String>> movies;
private static final String urlGetPid = "http://linkpictures.com";
private static final String TAG_SUCCESS = "success";
JSONArray jArray = null;
private static final String TAG_PID = "pid";
private static final String TAG_POSTER = "poster";
int success;
/**
* Empty constructor as per the Fragment documentation .
*/
public ImageGridFragment() {}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mImageThumbSize = getResources().getDimensionPixelSize(R.dimen.image_thumbnail_size);
mImageThumbSpacing = getResources().getDimensionPixelSize(R.dimen.image_thumbnail_spacing);
mAdapter = new ImageAdapter(getActivity());
ImageCacheParams cacheParams = new ImageCacheParams(getActivity(), IMAGE_CACHE_DIR);
cacheParams.setMemCacheSizePercent(0.25f); // Set memory cache to 25% of app memory
// The ImageFetcher takes care of loading images into our ImageView children asynchronously
mImageFetcher = new ImageFetcher(getActivity(), mImageThumbSize);
mImageFetcher.setLoadingImage(R.drawable.empty_photo);
mImageFetcher.addImageCache(getActivity().getSupportFragmentManager(), cacheParams);
}
@Override
public View onCreateView(
LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
movies = new ArrayList<HashMap<String, String>>();
new SearchDaMovies().execute();
final View v = inflater.inflate(R.layout.activity_show_movies, container, false);
final ListView mGridView = (ListView) v.findViewById(R.id.listView1);
Bundle extras = getActivity().getIntent().getExtras();
name = extras.getString("name");
year = extras.getString("year");
known = extras.getString("known");
genre = extras.getString("genre");
tag1 = extras.getString("tag1");
tag2 = extras.getString("tag2");
tag3 = extras.getString("tag3");
vote = extras.getString("vote");
description = extras.getString("description");
mGridView.setAdapter(mAdapter);
mGridView.setOnItemClickListener(this);
mGridView.setOnScrollListener(new AbsListView.OnScrollListener() {
@Override
public void onScrollStateChanged(AbsListView absListView, int scrollState) {
// Pause fetcher to ensure smoother scrolling when flinging
if (scrollState == AbsListView.OnScrollListener.SCROLL_STATE_FLING) {
mImageFetcher.setPauseWork(true);
} else {
mImageFetcher.setPauseWork(false);
}
}
@Override
public void onScroll(AbsListView absListView, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
}
});
return v;
}
@Override
public void onResume() {
super.onResume();
mImageFetcher.setExitTasksEarly(false);
mAdapter.notifyDataSetChanged();
}
@Override
public void onPause() {
super.onPause();
mImageFetcher.setPauseWork(false);
mImageFetcher.setExitTasksEarly(true);
mImageFetcher.flushCache();
}
@Override
public void onDestroy() {
super.onDestroy();
mImageFetcher.closeCache();
}
@TargetApi(16)
@Override
public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
if (Utils.hasJellyBean()) {
ActivityOptions options =
ActivityOptions.makeScaleUpAnimation(v, 0, 0, v.getWidth(), `v.getHeight());`
} else {
}
}
public class SearchDaMovies extends AsyncTask<String, String, String[]>{
String[] arrayS;
@Override
protected String[] doInBackground(String... args) {
try {
// send the query to JSON
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("name", name));
params.add(new BasicNameValuePair("year", year));
params.add(new BasicNameValuePair("genre", genre));
params.add(new BasicNameValuePair("known", known));
params.add(new BasicNameValuePair("tag1", tag1));
params.add(new BasicNameValuePair("tag2", tag2));
params.add(new BasicNameValuePair("tag3", tag3));
params.add(new BasicNameValuePair("vote", vote));
params.add(new BasicNameValuePair("poster", poster));
params.add(new BasicNameValuePair("description", description));
//receive the JSON data
JSONObject json = parser.makeHttpRequest(urlGetPid, params);
success = json.getInt(TAG_SUCCESS);
if (success == 1){
jArray = json.getJSONArray("Table");
for (int i =0; i<jArray.length();i++){
JSONObject c = jArray.getJSONObject(i);
String id = c.getString("pid");
String ame = c.getString("name");
String ear = c.getString("year");
String enre = c.getString("genre");
String nown = c.getString("known");
String ag1 = c.getString("tag1");
String ote = c.getString("vote");
if (ote.length()>14){
ote = ote.substring(0, ote.length() - 14);
}
oster = c.getString("poster");
//get the posters in an array
arrayS= new String[100];
arrayS[i]=oster;
Log.d("weird array ", arrayS[i]);
String escription = c.getString("description");
HashMap<String, String> map = new HashMap<String, String>();
map.put("pid", id);
map.put("name", ame);
map.put("year", ear);
map.put("genre", enre);
map.put("known",nown);
map.put("tag1", ag1);
map.put("vote", ote);
map.put("poster", oster);
map.put("description", escription);
movies.add(map);
}
}
} catch (JSONException e) {
e.printStackTrace();
}
return arrayS;
}
}
/**
* The main adapter that backs the GridView. This is fairly standard except the number of
* columns in the GridView is used to create a fake top row of empty views as we use a
* transparent ActionBar and don't want the real top row of images to start off covered by it.
*/
public final static String[] imageThumbUrls = new String[] {
"https://lh6.googleusercontent.com/-55osAWw3x0Q/URquUtcFr5I/AAAAAAAAAbs/rWlj1RUKrYI/s160-c/A%252520Photographer.jpg",
"https://lh4.googleusercontent.com/--dq8niRp7W4/URquVgmXvgI/AAAAAAAAAbs/-gnuLQfNnBA/s160-c/A%252520Song%252520of%252520Ice%252520and%252520Fire.jpg",
"https://lh5.googleusercontent.com/-7qZeDtRKFKc/URquWZT1gOI/AAAAAAAAAbs/hqWgteyNXsg/s160-c/Another%252520Rockaway%252520Sunset.jpg",
"https://lh3.googleusercontent.com/--L0Km39l5J8/URquXHGcdNI/AAAAAAAAAbs/3ZrSJNrSomQ/s160-c/Antelope%252520Butte.jpg",
"https://lh6.googleusercontent.com/-8HO-4vIFnlw/URquZnsFgtI/AAAAAAAAAbs/WT8jViTF7vw/s160-c/Antelope%252520Hallway.jpg",
"https://lh4.googleusercontent.com/-WIuWgVcU3Qw/URqubRVcj4I/AAAAAAAAAbs/YvbwgGjwdIQ/s160-c/Antelope%252520Walls.jpg",
};
private class ImageAdapter extends BaseAdapter {
private final Context mContext;
private int mItemHeight = 0;
private int mNumColumns = 0;
private int mActionBarHeight = 0;
private GridView.LayoutParams mImageViewLayoutParams;
// private ArrayList<HashMap<String, String>> movies = new ArrayList<HashMap<String, String>>();
public ImageAdapter(Context context) {
super();
mContext = context;
mImageViewLayoutParams = new GridView.LayoutParams(
LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
// Calculate ActionBar height
TypedValue tv = new TypedValue();
if (context.getTheme().resolveAttribute(
android.R.attr.actionBarSize, tv, true)) {
mActionBarHeight = TypedValue.complexToDimensionPixelSize(
tv.data, context.getResources().getDisplayMetrics());
}
}
@Override
public int getCount() {
// Size + number of columns for top empty row
return imageThumbUrls.length;
}
@Override
public Object getItem(int position) {
return position < mNumColumns ?
null : imageThumbUrls[position];
}
@Override
public long getItemId(int position) {
return position < mNumColumns ? 0 : position - mNumColumns;
}
@Override
public int getViewTypeCount() {
// Two types of views, the normal ImageView and the top row of empty views
return 2;
}
@Override
public int getItemViewType(int position) {
return (position < mNumColumns) ? 1 : 0;
}
@Override
public boolean hasStableIds() {
return true;
}
@Override
public View getView(int position, View convertView, ViewGroup container) {
// First check if this is the top row
if (position < mNumColumns) {
if (convertView == null) {
convertView = new View(mContext);
}
// Set empty view with height of ActionBar
convertView.setLayoutParams(new AbsListView.LayoutParams(
ViewGroup.LayoutParams.MATCH_PARENT, mActionBarHeight));
return convertView;
}
// Now handle the main ImageView thumbnails
ImageView imageView;
if (convertView == null) { // if it's not recycled, instantiate and initialize
imageView = new RecyclingImageView(mContext);
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
imageView.setLayoutParams(mImageViewLayoutParams);
} else { // Otherwise re-use the converted view
imageView = (ImageView) convertView;
}
// Check the height matches our calculated column width
if (imageView.getLayoutParams().height != mItemHeight) {
imageView.setLayoutParams(mImageViewLayoutParams);
}
// Finally load the image asynchronously into the ImageView, this also takes care of
// setting a placeholder image while the background thread runs
mImageFetcher.loadImage(imageThumbUrls[position],
imageView);
return imageView;
}
// * Sets the item height. Useful for when we know the column width so the height can be set
// * to match.
//
// * @param height
public void setItemHeight(int height) {
if (height == mItemHeight) {
return;
}
mItemHeight = height;
mImageViewLayoutParams =
new GridView.LayoutParams(LayoutParams.MATCH_PARENT, mItemHeight);
mImageFetcher.setImageSize(height);
notifyDataSetChanged();
}
public void setNumColumns(int numColumns) {
mNumColumns = numColumns;
}
public int getNumColumns() {
return mNumColumns;
}
}