我有一个自己的ContentProvider实现,它支持通过重载ContentProvider.openInputStream和openOutputStream方法来保存/加载图像到每个记录。本地一切工作正常。但现在我正在从URL下载图像,然后将它们保存到ContentProvider中。在ContentProvider中下载和存储图像
最佳的解决方案,但不起作用:为了避免在内存中创建巨大的位图,我想直接将传入的HTTPS流写入文件(选项1)。但是当我加载位图时,BitmapFactory会引发错误。
作品,但没有最佳的解决方案:如果我从传入HTTPS数据流(选项2)到内存中加载位图,然后保存(压缩),它的ContentProvider的 - 然后加载位以后工作正常。
所以我想知道我在做什么错了?
这里是一些要测试的网址:
https://lh5.ggpht.com/goggZXKLiJst1uSWPmgzk9j2WqdNiPAQZyb59tddL1WIHQgb-cPV7uqGuqECdu7ChiW8vve_2UC-Ta16YfbLlA=s192 https://lh4.ggpht.com/EizCbwoyAndISCf1b2tjPkOSMEl-jJZoPJ386RtQ7Q4kJ-1tUDEhqweXrPP-jX7pbCAoCUYN7iw1beyiI9JTFAo=s160
示例代码(downloadDirect导致错误的位图,downloadIndirect作品):
private void downloadDirect(String url, int key, Context context)
throws MalformedURLException, IOException {
InputStream is = download(url);
OutputStream os = openOutputStream(context, key);
final byte[] buffer = new byte[BUFFER_SIZE];
while (is.read(buffer) >= 0) {
os.write(buffer);
}
os.close();
is.close();
}
private void downloadIndirect(String url, int key, Context context)
throws MalformedURLException, IOException {
InputStream is = download(url);
Bitmap bitmap = BitmapFactory.decodeStream(is);
saveBitmap(context, key, bitmap);
}
private InputStream download(String url) throws MalformedURLException,
IOException {
URL newUrl = new URL(url);
HttpURLConnection con = (HttpURLConnection) newUrl.openConnection();
return con.getInputStream();
}
这些都是ContentProvider的方法:
public static InputStream openInputStream(Context context, Uri contentUri,
int key) throws FileNotFoundException {
Uri uri = ContentUris.withAppendedId(contentUri, key);
return context.getContentResolver().openInputStream(uri);
}
public static OutputStream openOutputStream(Context context,
Uri contentUri, int key) throws FileNotFoundException {
Uri uri = ContentUris.withAppendedId(contentUri, key);
return context.getContentResolver().openOutputStream(uri);
}
protected static void saveBitmap(Context context, Uri contentUri,
String basePath, int key, Bitmap value, boolean updateDatabase) {
Uri uri = ContentUris.withAppendedId(contentUri, key);
try {
if (value == null) {
deleteFile(uri, basePath, context, true);
return;
}
OutputStream outStream;
try {
outStream = openOutputStream(context, contentUri, key);
ImageUtils.saveToStream(value, outStream,
Bitmap.CompressFormat.PNG);
outStream.close();
Log.d(TAG,
"Image (" + value.getWidth() + "x" + value.getHeight()
+ "pixels) saved to " + uri.toString());
} catch (FileNotFoundException e) {
e.printStackTrace();
Log.e(TAG, "Could not save image to " + uri.toString());
} catch (IOException e) {
e.printStackTrace();
Log.e(TAG, "Could not save image to " + uri.toString());
}
} finally {
if (updateDatabase) {
ContentValues values = new ContentValues();
// modified column will be added automatically
context.getContentResolver().update(uri, values, null, null);
}
}
}
所述的ContentProvider的中openFile方法重写这样的:
public ParcelFileDescriptor openFile(Uri uri, String mode)
throws FileNotFoundException {
ContextWrapper cw = new ContextWrapper(getContext());
// path to /data/data/yourapp/app_data/dir
File directory = cw.getDir(basePath, Context.MODE_MULTI_PROCESS);
directory.mkdirs();
long id = ContentUris.parseId(uri);
File path = new File(directory, String.valueOf(id));
int imode = 0;
if (mode.contains("w")) {
imode |= ParcelFileDescriptor.MODE_WRITE_ONLY;
if (!path.exists()) {
try {
path.createNewFile();
} catch (IOException e) {
Log.e(tag, "Could not create file: " + path.toString());
e.printStackTrace();
}
}
}
if (mode.contains("r"))
imode |= ParcelFileDescriptor.MODE_READ_ONLY;
if (mode.contains("+"))
imode |= ParcelFileDescriptor.MODE_APPEND;
return ParcelFileDescriptor.open(path, imode);
}
'保存/加载图像到每个记录???对每个记录?对不起,我已经不在线了。 – greenapps
您没有显示'openOutputStream(context,key)的代码;'并没有使用'downloadDirect()'和原始大小来告诉保存文件的大小。 – greenapps
对不起,我添加了方法openFile(...),您必须重写,以便ContentResolver.openOutputStream(...)在上面工作。我发现问题了。我只是以错误的方式阅读输入流。这导致了错误的文件。 – Matthias