我正在开发一个 Android 应用程序,它是一个图像库,其中的图像是从互联网下载的,以显示在 smathphone 的屏幕上。图像一次显示一个,应用程序有一个按钮来共享显示的图像。
按照我在一些 StackOverflow 帖子中找到的指示,表明共享图像的正确方法是使用 ContentProvider 我已经实现了以下代码,用于共享某些应用程序(例如 Twitter、Gmail ......)的图像,但是不适用于其他人(Facebook、Yahoo、MMS ...)。
然后我展示了使用的代码,希望你能帮助我获得正确的实现,以便在所有应用程序中共享图像。
最初我捕获按钮按下以共享:
@Override
public boolean onOptionsItemSelected(MenuItem item) {
if (item.getItemId() == R.id.menu_share) {
// I get the image being displayed on the screen
View root = getView();
ImageView imageView = (ImageView) root.findViewById(R.id.image);
Drawable imageToShareDrawable = imageView.getDrawable();
if (imageToShareDrawable instanceof BitmapDrawable) {
// I convert the image to Bitmap
Bitmap imageToShare = ((BitmapDrawable) imageToShareDrawable).getBitmap();
// Name of de image extracted from a bean property
String fileName = quote.getImage();
// I keep the image in the folder "files" of internal storage application
TempInternalStorage.createCachedFile(fileName, imageToShare, getActivity().getApplicationContext());
// I start the Activity to select the application to share the image after the intent Built with the method "getDefaultShareIntent"
startActivity(getDefaultShareIntent(fileName));
} else {
Toast.makeText(getActivity().getApplicationContext(), "Please wait, the quote is being downloaded", Toast.LENGTH_SHORT).show();
}
}
return true;
}
将图像保存到应用程序内部存储的方法如下:
public static void createCachedFile(String fileName, Bitmap image, Context context) {
try {
File file = new File(context.getFilesDir(), fileName);
if (!file.exists()) {
FileOutputStream fos = new FileOutputStream(file);
image.compress(Bitmap.CompressFormat.JPEG, 100, fos);
fos.flush();
fos.close();
}
} catch (Exception e) {
Log.e("saveTempFile()", "**** Error");
}
}
构造 Intent 以共享它的方法:
private Intent getDefaultShareIntent(String fileName) {
final Intent shareIntent = new Intent();
shareIntent.setAction(Intent.ACTION_SEND);
shareIntent.setType("image/jpeg");
shareIntent.putExtra(Intent.EXTRA_TEXT, "Test text");
shareIntent.putExtra(Intent.EXTRA_STREAM, Uri.parse("content://" + CachedFileProvider.AUTHORITY + File.separator + "img" + File.separator + fileName));
shareIntent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
return shareIntent;
}
最后ContentProvider代码如下:
public class CachedFileProvider extends ContentProvider {
private static final String CLASS_NAME = "CachedFileProvider";
public static final String AUTHORITY = "com.example.appname.cachefileprovider";
private UriMatcher uriMatcher;
@Override
public boolean onCreate() {
uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
uriMatcher.addURI(AUTHORITY, "img/*", 1);
return true;
}
@Override
public ParcelFileDescriptor openFile(Uri uri, String mode) throws FileNotFoundException {
String LOG_TAG = CLASS_NAME + " - openFile";
Log.i(LOG_TAG, "Called with uri: '" + uri + "'." + uri.getLastPathSegment());
switch (uriMatcher.match(uri)) {
case 1:
String fileLocation = getContext().getFilesDir() + File.separator + uri.getLastPathSegment();
ParcelFileDescriptor image = ParcelFileDescriptor.open(new File(fileLocation), ParcelFileDescriptor.MODE_READ_ONLY);
return image;
default:
Log.i(LOG_TAG, "Unsupported uri: '" + uri + "'.");
throw new FileNotFoundException("Unsupported uri: " + uri.toString());
}
}
@Override
public int update(Uri uri, ContentValues contentvalues, String s, String[] as) {
return 0;
}
@Override
public int delete(Uri uri, String s, String[] as) {
return 0;
}
@Override
public Uri insert(Uri uri, ContentValues contentvalues) {
return null;
}
@Override
public String getType(Uri uri) {
return null;
}
@Override
public Cursor query(Uri uri, String[] projection, String s, String[] as1, String s1) {
MatrixCursor c = null;
Log.i(">>>> projection", java.util.Arrays.toString(projection));
String fileLocation = getContext().getFilesDir() + File.separator + uri.getLastPathSegment();
File file = new File(fileLocation);
long time = System.currentTimeMillis();
c = new MatrixCursor(new String[] { "_id", "_data", "orientation", "mime_type", "datetaken", "_display_name" });
c.addRow(new Object[] { 0, file, 0, "image/jpeg", time, uri.getLastPathSegment() });
return c;
}
@Override
public String[] getStreamTypes(Uri uri, String mimeTypeFilter) {
return null;
}
}
我发现,当图像共享时,一些应用程序只调用方法“查询”(这些是代码不起作用的地方,我无法共享图像),而其他应用程序也调用方法“查询”也调用方法“openFile”,这些确实有效,我可以分享图像。
我希望你能帮助我,非常感谢你提前。