我正在通过URL连接将图像下载到受保护的内存中。下载图像后，MainActivity中的BroadcastReceiver应该更新我的主片段中的GridView以包括新下载的图像。
从存储中加载时，Gridview会正确填充。但是，从BroadcastReceiver更新时，每个连续的图像都会替换单个子视图中的最后一个图像，而不是按预期填充新的子视图。
任何建议将不胜感激。
这是我的MainActivity：
Context mContext;
DisplayImageReceiver displayImageReceiver;
public static final String ACTION_SHOW_IMAGE = "com.mack.john.mackjohn_ce06.ACTION_SHOW_IMAGE";
// System generated methods
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mContext = this;
displayImageReceiver = new DisplayImageReceiver();
IntentFilter filter = new IntentFilter(ACTION_SHOW_IMAGE);
filter.addAction(ACTION_SHOW_IMAGE);
registerReceiver(displayImageReceiver, filter);
populateGrid();
}
@Override
protected void onDestroy() {
super.onDestroy();
unregisterReceiver(displayImageReceiver);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu_main, menu);
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
if(item.getItemId() == R.id.menu_download) {
Intent imageIntentService = new Intent(this, ImageIntentService.class);
startService(imageIntentService);
}
return super.onOptionsItemSelected(item);
}
// Custom methods
private void populateGrid() {
getSupportFragmentManager()
.beginTransaction()
.replace(R.id.gridFrame, GridFragment.newInstance(this))
.commit();
}
// Broadcast Receiver
private class DisplayImageReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
GridFragment.populateGrid(GridFragment.mView);
}
}
这是我的片段：
public class GridFragment extends Fragment {
// Class properties
public static int mImageCount = 0;
private static Context mContext;
public static View mView;
// Constructor
public GridFragment() {}
// System generated methods
public static GridFragment newInstance(Context context) {
Bundle args = new Bundle();
mContext = context;
GridFragment fragment = new GridFragment();
fragment.setArguments(args);
return fragment;
}
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_image_grid, container, false);
mView = view;
countFiles();
populateGrid(view);
return view;
}
// Custom methods
public void countFiles() {
File protectedStorage = getActivity().getExternalFilesDir("images");
mImageCount = protectedStorage.listFiles().length;
}
public static void populateGrid(View view) {
File protectedStorage = mContext.getExternalFilesDir("images");
File[] files = protectedStorage.listFiles();
mImageCount = files.length;
ImageGridAdapter imageGridAdapter = new ImageGridAdapter(mContext, files);
GridView imageGrid = view.findViewById(R.id.imageGrid);
TextView emptyState = view.findViewById(R.id.emptyState);
if(mImageCount > 0) {
imageGrid.setVisibility(View.VISIBLE);
emptyState.setVisibility(View.GONE);
imageGrid.setAdapter(imageGridAdapter);
}
else {
imageGrid.setVisibility(View.GONE);
emptyState.setVisibility(View.VISIBLE);
}
}
}
这是我的适配器：
public class ImageGridAdapter extends BaseAdapter {
// Class properties
public static final String TAG = "ImageGridAdapter";
private static final int ID_CONSTANT = 0x0000001;
private final Context mContext;
private final File[] mFiles;
// Constructor
public ImageGridAdapter(Context mContext, File[] mFiles) {
this.mContext = mContext;
this.mFiles = mFiles;
}
// System generated methods
@Override
public int getCount() {
// Return number of items in collection
if(mFiles != null) {
return mFiles.length;
}
else {
Log.i(TAG, "getCount: There is no collection");
return 0;
}
}
@Override
public Object getItem(int position) {
// Return an item at a specified position
if(mFiles != null && position >= 0 && position < mFiles.length) {
return mFiles[position];
}
else {
Log.i(TAG, "getItem: There was a problem retreiving an item");
return null;
}
}
@Override
public long getItemId(int position) {
// Return a unique ID for an item at a specified position
if(mFiles != null && position >= 0 && position < mFiles.length) {
return ID_CONSTANT + position;
}
else {
Log.i(TAG, "getItemId: There was a problem assigning an ID");
return 0;
}
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// Return a unique child view for an item at a specified position
if(convertView == null) {
convertView = LayoutInflater.from(mContext).inflate(R.layout.cell_image_grid, parent, false);
}
File imageFile = mFiles[position];
BitmapFactory.Options options = new BitmapFactory.Options();
options.inSampleSize = 8;
Bitmap image = BitmapFactory.decodeFile(imageFile.getAbsolutePath(), options);
ImageView gridCell = convertView.findViewById(R.id.gridCell);
gridCell.setImageBitmap(image);
return convertView;
}
}
这是我的IntentService代码：
public static final String TAG = "ImageIntentService";
private static String currentFileName;
public static File protectedStorage;
private final String URL_BASE = "https://i.imgur.com/";
private final String[] IMAGES = {
"Df9sV7x.jpg", "nqnegVs.jpg", "JDCG1tP.jpg",
"tUvlwvB.jpg", "2bTEbC5.jpg", "Jnqn9NJ.jpg",
"xd2M3FF.jpg", "atWe0me.jpg", "UJROzhm.jpg",
"4lEPonM.jpg", "vxvaFmR.jpg", "NDPbJfV.jpg",
"ZPdoCbQ.jpg", "SX6hzar.jpg", "YDNldPb.jpg",
"iy1FvVh.jpg", "OFKPzpB.jpg", "P0RMPwI.jpg",
"lKrCKtM.jpg", "eXvZwlw.jpg", "zFQ6TwY.jpg",
"mTY6vrd.jpg", "QocIraL.jpg", "VYZGZnk.jpg",
"RVzjXTW.jpg", "1CUQgRO.jpg", "GSZbb2d.jpg",
"IvMKTro.jpg", "oGzBLC0.jpg", "55VipC6.jpg"
};
// Constructor
public ImageIntentService() {
super("ImageIntentService");
}
// System generated methods
@Override
protected void onHandleIntent(Intent intent) {
checkForSavedImages();
}
@Override
public void onCreate() {
super.onCreate();
protectedStorage = getExternalFilesDir("images");
}
@Override
public void onDestroy() {
super.onDestroy();
}
// Custom methods
private void checkForSavedImages() {
for (int i = 0; i < IMAGES.length; i++) {
File imageFile = new File(protectedStorage, IMAGES[i]);
if (imageFile.exists()) {
Log.i(TAG, "checkForSavedImages: " + IMAGES[i] + " found in protected storage");
int fileCount = protectedStorage.listFiles().length;
Log.i(TAG, "checkForSavedImages: " + fileCount + " files in protected storage");
// TODO: Send file with broadcast receiver
broadcast();
}
else {
Log.i(TAG, "checkForSavedImages: " + IMAGES[i] + " NOT found in protected storage");
// TODO: Download image file and send with broadcast receiver
currentFileName = IMAGES[i];
String urlString = URL_BASE + IMAGES[i];
createConnection(urlString);
}
}
}
private void broadcast() {
Intent broadcastIntent = new Intent(MainActivity.ACTION_SHOW_IMAGE);
sendBroadcast(broadcastIntent);
}
// Data Helper
public class ImageDownloadHelper extends AsyncTask<String, Void, Void> {
// System generated methods
@Override
protected Void doInBackground(String... strings) {
String urlString = strings[0];
downloadData(urlString);
return null;
}
}
// Data helper methods
public void createConnection(String urlString) {
ConnectivityManager connectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
if (connectivityManager != null) {
NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
if (networkInfo != null) {
boolean isConnected = networkInfo.isConnected();
if (isConnected) {
ImageDownloadHelper imageDownloadHelper = new ImageDownloadHelper();
imageDownloadHelper.execute(urlString);
} else {
Toast.makeText(this, getString(R.string.no_connection), Toast.LENGTH_SHORT);
}
} else {
Toast.makeText(this, getString(R.string.no_connection), Toast.LENGTH_SHORT);
}
} else {
Toast.makeText(this, getString(R.string.no_connection), Toast.LENGTH_SHORT);
}
}
private void downloadData(String urlString) {
try {
URL imageURL = new URL(urlString);
HttpsURLConnection connection = (HttpsURLConnection) imageURL.openConnection();
InputStream inputStream = connection.getInputStream();
byte[] imageDate = IOUtils.toByteArray(inputStream);
inputStream.close();
connection.disconnect();
saveImage(imageDate);
}
catch (IOException e) {
e.printStackTrace();
}
}
private void saveImage(byte[] data) {
File imageFile = new File(protectedStorage, currentFileName);
try {
FileOutputStream fileOutputStream = new FileOutputStream(imageFile);
fileOutputStream.write(data);
fileOutputStream.close();
Log.i(TAG, "saveImage: Image Saved");
broadcast();
}
catch (IOException e) {
e.printStackTrace();
}
}
答案 0 :(得分：0)
已解决：
更改了我的保存方法，以回调到检查受保护的存储中文件的方法：
private void saveImage(byte[] data) {
File imageFile = new File(protectedStorage, currentFileName);
try {
FileOutputStream fileOutputStream = new FileOutputStream(imageFile);
fileOutputStream.write(data);
fileOutputStream.close();
Log.i(TAG, "saveImage: Image Saved");
//broadcast();
checkForSavedImages();
}
catch (IOException e) {
e.printStackTrace();
}
}
然后将检查方法更改为在遇到未存储的文件时中断：
private void checkForSavedImages() {
for (int i = 0; i < IMAGES.length; i++) {
File imageFile = new File(protectedStorage, IMAGES[i]);
if (imageFile.exists()) {
Log.i(TAG, "checkForSavedImages: " + IMAGES[i] + " found in protected storage");
int fileCount = protectedStorage.listFiles().length;
Log.i(TAG, "checkForSavedImages: " + fileCount + " files in protected storage");
// TODO: Send file with broadcast receiver
broadcast();
}
else {
Log.i(TAG, "checkForSavedImages: " + IMAGES[i] + " NOT found in protected storage");
// TODO: Download image file and send with broadcast receiver
currentFileName = IMAGES[i];
String urlString = URL_BASE + IMAGES[i];
createConnection(urlString);
break;
}
}
}