我发现了解决方案的两种变体。两者都涉及将位图保存到存储中,但图像不会出现在图库中。
第一个变体:
保存到外部存储
1. 设置权限
添加到AndroidManifest.xml标签之前
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" android:maxSdkVersion="18"/>
2、保存方法:
/**
* Saves the image as PNG to the app's private external storage folder.
* @param image Bitmap to save.
* @return Uri of the saved file or null
*/
private Uri saveImageExternal(Bitmap image) {
//TODO - Should be processed in another thread
Uri uri = null;
try {
File file = new File(getExternalFilesDir(Environment.DIRECTORY_PICTURES), "to-share.png");
FileOutputStream stream = new FileOutputStream(file);
image.compress(Bitmap.CompressFormat.PNG, 90, stream);
stream.close();
uri = Uri.fromFile(file);
} catch (IOException e) {
Log.d(TAG, "IOException while trying to write file for sharing: " + e.getMessage());
}
return uri;
}
3. 检查存储可访问性
外部存储可能无法访问,因此您应该在尝试保存之前检查它:https://developer.android.com/training/data-storage/files https://developer.android.com/training/data-storage/files
/**
* Checks if the external storage is writable.
* @return true if storage is writable, false otherwise
*/
public boolean isExternalStorageWritable() {
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state)) {
return true;
}
return false;
}
第二种变体
使用 FileProvider 保存到 cacheDir。它不需要任何权限。
1.在AndroidManifest.xml中设置FileProvider
<manifest>
...
<application>
...
<provider
android:name="android.support.v4.content.FileProvider"
android:authorities="com.mydomain.fileprovider"
android:exported="false"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="@xml/file_paths" />
</provider>
...
</application>
</manifest>
2. 添加路径到res/xml/file_paths.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
<cache-path name="shared_images" path="images/"/>
</paths>
</resources>
3、保存方法:
/**
* Saves the image as PNG to the app's cache directory.
* @param image Bitmap to save.
* @return Uri of the saved file or null
*/
private Uri saveImage(Bitmap image) {
//TODO - Should be processed in another thread
File imagesFolder = new File(getCacheDir(), "images");
Uri uri = null;
try {
imagesFolder.mkdirs();
File file = new File(imagesFolder, "shared_image.png");
FileOutputStream stream = new FileOutputStream(file);
image.compress(Bitmap.CompressFormat.PNG, 90, stream);
stream.flush();
stream.close();
uri = FileProvider.getUriForFile(this, "com.mydomain.fileprovider", file);
} catch (IOException e) {
Log.d(TAG, "IOException while trying to write file for sharing: " + e.getMessage());
}
return uri;
}
有关文件提供程序的更多信息 -https://developer.android.com/reference/android/support/v4/content/FileProvider https://developer.android.com/reference/android/support/v4/content/FileProvider
压缩和保存可能非常耗时,因此应该在不同的线程中完成
实际分享
/**
* Shares the PNG image from Uri.
* @param uri Uri of image to share.
*/
private void shareImageUri(Uri uri){
Intent intent = new Intent(android.content.Intent.ACTION_SEND);
intent.putExtra(Intent.EXTRA_STREAM, uri);
intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
intent.setType("image/png");
startActivity(intent);
}