这是关于Android应用中图像保存的问题。 我正在努力制作一个udacity project.Link - https://docs.google.com/document/d/1gtXUu1nzLGWrGfVCD6tEA0YHoYA9UNyT2yByqjJemp8/pub?embedded=true
的热门电影应用我在ImageAdapter中有用于图像下载的毕加索库 -
这是我的ImageAdapter代码 -
package jindal5.mayank.popular_movies_14ce10032_gsc;
public class ImageAdapter extends BaseAdapter {
private String drawablePrefix;
private Context mContext;
private ArrayList<String> mThumbUris;
private ArrayList<String> mov_id_arr;
private ArrayList<String> mov_tit_arr;
public ImageAdapter(Context c) {
mContext = c;
String packName=mContext.getPackageName();
drawablePrefix="android.resource://" +packName+ "/";
ArrayList<String> mov_id_arr =new ArrayList<>();
ArrayList<String> mov_tit_arr=new ArrayList<>();
mov_tit_arr.add("asdf");
mov_tit_arr.add("asdf");
mov_tit_arr.add("asdf");
mov_tit_arr.add("asdf");
mov_tit_arr.add("asdf");
mov_tit_arr.add("asdf");
ArrayList<String> uriPaths=new ArrayList<>();// place your drawables.
uriPaths.add(drawablePrefix+ R.drawable.sample_0);
uriPaths.add(drawablePrefix+ R.drawable.sample_0);
uriPaths.add(drawablePrefix+ R.drawable.sample_0);
uriPaths.add(drawablePrefix+ R.drawable.sample_0);
uriPaths.add(drawablePrefix+ R.drawable.sample_0);
uriPaths.add(drawablePrefix+ R.drawable.sample_0);
mThumbUris=uriPaths;
}
public int getCount() {
return mThumbUris.size();
}
public Object getItem(int position) {
return mThumbUris.get(position);
}
public long getItemId(int position) {
return 0;
}
// create a new ImageView for each item referenced by the Adapter
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView;
if (convertView == null) {
// if it's 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;
}
Uri imgUri=Uri.parse(mThumbUris.get(position));
Picasso.with(mContext)
.load(imgUri)
.placeholder(R.drawable.sample_0)
.centerCrop()
.resize(400,400)
.into(imageView);
imageView.setImageResource(mThumbIds[position]);
// imageView.setAdjustViewBounds(true);
return imageView;
}
public ArrayList<String> getUriList(){
return mThumbUris;
}
public ArrayList<String> getidlist(){
return mov_id_arr;
}
public ArrayList<String> gettitlist(){
return mov_tit_arr;
}
// references to our images
private Integer[] mThumbIds = {
R.drawable.sample_2, R.drawable.sample_3,
R.drawable.sample_4, R.drawable.sample_5,
R.drawable.sample_6, R.drawable.sample_7,
R.drawable.sample_0, R.drawable.sample_1,
R.drawable.sample_2, R.drawable.sample_3,
R.drawable.sample_4, R.drawable.sample_5,
R.drawable.sample_6, R.drawable.sample_7,
R.drawable.sample_0, R.drawable.sample_1,
R.drawable.sample_2, R.drawable.sample_3,
R.drawable.sample_4, R.drawable.sample_5,
R.drawable.sample_6, R.drawable.sample_7
};
}
现在我有两个问题 -
3.当我改变设备方向时，我面临同样的问题。
这是我主要活动的片段 -
package jindal5.mayank.popular_movies_14ce10032_gsc;
/**
* A placeholder fragment containing a simple view.
*/
public class MainActivityFragment extends Fragment {
public ImageAdapter imag_adap;
public String movieJsonStr;
public ArrayList<String > tit_arr = new ArrayList<String>();
public ArrayList<String > rel_dat_arr = new ArrayList<String>();
public ArrayList<String > url1_arr = new ArrayList<String>();
public ArrayList<String > over_arr = new ArrayList<String>();
public ArrayList<String > id_arr = new ArrayList<String>();
public String put_ext_tit;
public String rel_date_ext;
public String url_for_pos_ex;
public String over_ex;
public String id_ex;
public MainActivityFragment() {
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Add this line in order for this fragment to handle menu events.
setHasOptionsMenu(true);
}
@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
inflater.inflate(R.menu.menu_fragment, menu);
}
@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();
if (id == R.id.action_refresh) {
//SharedPreferences share = PreferenceManager.getDefaultSharedPreferences();
// String order = share.getString()
getimage imageTask = new getimage();
imageTask.execute("popularity.desc");
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootview = inflater.inflate(R.layout.fragment_main, container, false);
GridView grid = (GridView) rootview.findViewById(R.id.gridView);
imag_adap = new ImageAdapter(getActivity());
grid.setAdapter(imag_adap);
grid.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
String[] tit1 = tit_arr.toArray(new String[tit_arr.size()]);
String[] rel_date = rel_dat_arr.toArray(new String[rel_dat_arr.size()]);
String[] url_for_pos = url1_arr.toArray(new String[url1_arr.size()]);
String[] over = url1_arr.toArray(new String[over_arr.size()]);
String[] id = id_arr.toArray(new String[over_arr.size()]);
// Log.v("mayank",tit1[3]);
try{
put_ext_tit = tit1[i];
rel_date_ext = rel_date[i];
url_for_pos_ex = url_for_pos[i];
over_ex = over[i];
id_ex =id[i];
Intent intent = new Intent(getActivity(),det_mov.class);
//.putExtra(Intent.EXTRA_TEXT,put_ext_tit);
Bundle extras = new Bundle();
extras.putString("title",put_ext_tit);
extras.putString("rel_date",rel_date_ext);
extras.putString("url_pos",url_for_pos_ex);
extras.putString("over_ex",over_ex);
extras.putString("id_ex", id_ex);
extras.putInt("posit",i);
intent.putExtras(extras);
startActivity(intent);
}
catch (ArrayIndexOutOfBoundsException p){
Log.e("mayank","reg",p);
}
}
});
return rootview;
}
public class getimage extends AsyncTask<String, String, String[]> {
ConnectivityManager conMgr = (ConnectivityManager) getActivity().getSystemService(Context.CONNECTIVITY_SERVICE);
private final String LOG_TAG = getimage.class.getSimpleName();
public int count;
String[] pos_path;
String[] mov_id;
String[] tit;
String[] rev;
String[] rel_dat;
String[] url1;
String[] over;
String[] id;
public ImageAdapter getad(){
return imag_adap;
}
@Override
protected String[] doInBackground(String... params) {
HttpURLConnection urlConnection = null;
BufferedReader reader = null;
try {
final String movie_url_str = "http://api.themoviedb.org/3/discover/movie?sort_by="+ params[0] +"&api_key=8d7a48043ba1d3348181e2b6615cedc7";
URL movie_url = new URL(movie_url_str);
urlConnection = (HttpURLConnection) movie_url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.connect();
InputStream inputStream = urlConnection.getInputStream();
StringBuffer buffer = new StringBuffer();
if (inputStream == null) {
return null;
}
reader = new BufferedReader(new InputStreamReader(inputStream));
String line;
while ((line = reader.readLine()) != null) {
buffer.append(line + "\n");
}
if (buffer.length() == 0) {
return null;
}
movieJsonStr = buffer.toString();
JSONObject movieJson = new JSONObject(movieJsonStr);
JSONArray movieJsonarray = movieJson.getJSONArray("results");
count = movieJsonarray.length();
pos_path = new String[count];
mov_id = new String[count];
tit = new String[count];
rev = new String[count];
rel_dat = new String[count];
url1 = new String[count];
over = new String[count];
id = new String[count];
for(int i=0;i<count;i++){
JSONObject sin_movie = movieJsonarray.getJSONObject(i);
pos_path[i] = sin_movie.getString("poster_path");
over[i] = sin_movie.getString("overview");
Uri.Builder url_for_poster = new Uri.Builder();
String qw = "t";
String as = "p";
Uri.Builder url_build = url_for_poster.scheme("http").authority("image.tmdb.org").appendPath(qw).appendPath(as).appendPath("w500").appendEncodedPath(pos_path[i]);
url1[i] = url_build.toString();
// mov_id[i] = sin_movie.getString("id");
tit[i] = sin_movie.getString("title");
//rev[i] = sin_movie.getString("review");
rel_dat[i] = sin_movie.getString("release_date");
id[i] = sin_movie.getString("id");
publishProgress((String)(tit[i]),(String)(rel_dat[i]),(String)(url1[i]),(String)(over[i]),(String)(id[i]));
Log.v(LOG_TAG, "Forecast string: " + id[i]);
}
} catch (IOException | JSONException e) {
Log.e(LOG_TAG, "Error ", e);
return null;
}
finally {
if (urlConnection != null) {
urlConnection.disconnect();
}
if (reader != null) {
try {
reader.close();
} catch (final IOException e) {
Log.e(LOG_TAG, "Error closing stream", e);
}
}
}
return pos_path;
}
@Override
protected void onProgressUpdate(String... values) {
tit_arr.add(values[0]);
rel_dat_arr.add(values[1]);
url1_arr.add(values[2]);
over_arr.add(values[3]);
id_arr.add(values[4]);
}
@Override
protected void onPostExecute(String[] result) {
ArrayList<String> uriPaths = imag_adap.getUriList();
uriPaths.clear();
// ImageView[] im_vi = new ImageView[count];
for(int j=0;j<count;j++) {
String pos_sin_path = pos_path[j];
String id_mov = id[j];
Uri.Builder url_for_poster = new Uri.Builder();
Uri.Builder url_for_rev = new Uri.Builder();
String qw = "t";
String as = "p";
Uri.Builder url_build = url_for_poster.scheme("http").authority("image.tmdb.org").appendPath(qw).appendPath(as).appendPath("w500").appendEncodedPath(pos_sin_path);
String url = url_build.toString();
Uri.Builder url_build_rev = url_for_rev.scheme("http").encodedAuthority("api.themoviedb.org/3/movie").appendPath(id_mov).appendPath("reviews");
uriPaths.add(url);
// mov_title.add(tit[j]);
//mov_id_arr.add(id);
// mov_tit_arr.add(title);
// }
//catch (UnsupportedEncodingException e){
//}
//url_build.clearQuery();
//Picasso.with(getActivity()).load("http://image.tmdb.org/t/p/w185//nBNZadXqJSdt05SHLqgT0HuC5Gm.jpg").into(im_vi[j]);
//imag_adap.getItem(j) = im_vi[j];\
}
imag_adap.notifyDataSetChanged();
}
}
}
寻求帮助因为我是android的新手。
答案 0 :(得分：1)
当我关闭我的应用并再次打开时，我会看到本地图像显示而不是上次下载的图像。有人告诉你，在使用文件或内容提供商下载到本地内存后，你必须保存这些图像。但我不知道该怎么办？
这是预料之中的，因为您的设备上没有任何照片。将图像保存在数据库中（SQLite）如果您希望它在您返回应用程序时保持不变并可用。或者每次重新启动活动时都加载它们，最好是通过AsyncTask。
要在SQLite数据库中存储图像，请查看How to store(bitmap image) and retrieve image from sqlite database in android?告诉您有关保存和检索图像的所有信息。
答案 1 :(得分：0)
试试这个，
<强>答案-1：
尝试将适配器初始化逻辑更改为onCreateView为onCreate。 把这一行放在onCreate上。
imag_adap = new ImageAdapter(getActivity());
<强>答案-2：
下载图像后，将uri路径保存在数据库或文件或共享首选项中。然后在创建适配器中检索uri。
ArrayList<String> uriPathsFromDb=getListOfUriFromDatabase();
if(uriPathsFromDb.size()==0){
ArrayList<String> uriPaths=new ArrayList<>();// place your drawables.
uriPaths.add(drawablePrefix+ R.drawable.sample_0);
uriPaths.add(drawablePrefix+ R.drawable.sample_0);
uriPaths.add(drawablePrefix+ R.drawable.sample_0);
uriPaths.add(drawablePrefix+ R.drawable.sample_0);
uriPaths.add(drawablePrefix+ R.drawable.sample_0);
uriPaths.add(drawablePrefix+ R.drawable.sample_0);
mThumbUris=uriPaths;
}else{
mThumbUris=uriPathsFromDb;
}