[英]How to get android lock screen wallpaper?
I use the code below to retrieve the android lock screen wallpaper on an android 8.1 phone: 我使用下面的代码检索android 8.1手机上的android锁屏壁纸:
WallpaperManager manager = WallpaperManager.getInstance(getActivity());
ParcelFileDescriptor pfd = manager.getWallpaperFile(WallpaperManager.FLAG_LOCK);
if (pfd == null) // pfd is always null for FLAG_LOCK, why?
return;
Bitmap lockScreenWallpaper = BitmapFactory.decodeFileDescriptor(pfd.getFileDescriptor());
// ...
I have granted the READ_EXTERNAL_STORAGE
permission and set a lock screen wallpaper beforehand. 我已经授予了READ_EXTERNAL_STORAGE
权限并预先设置了锁定屏幕壁纸。
I run the demo on a real phone, and found the pfd
is always null for FLAG_LOCK
, so I cannot get the lock screen wallpaper. 我在真正的手机上运行演示,发现FLAG_LOCK
的pfd
总是为FLAG_LOCK
,所以我无法获得锁屏壁纸。 Please help fix the problem, thanks. 请帮忙解决问题,谢谢。
I find the answer myself, I hope it can help others with the same question. 我自己找到了答案,我希望它能帮助其他人解决同样的问题。
The official docs for getWallpaperFile says: If no lock-specific wallpaper has been configured for the given user, then this method will return null when requesting FLAG_LOCK rather than returning the system wallpaper's image file.
getWallpaperFile的官方文档说: If no lock-specific wallpaper has been configured for the given user, then this method will return null when requesting FLAG_LOCK rather than returning the system wallpaper's image file.
The description is vague, at least not clear enough, what does it mean? 描述含糊不清,至少不够清楚,这是什么意思? If you set a photo as both lock screen and home screen wallpaper, the two share the same file, then by calling 如果将照片设置为锁定屏幕和主屏幕壁纸,则两者共享同一文件,然后通过调用
ParcelFileDescriptor pfd = wallpaperManager.getWallpaperFile(WallpaperManager.FLAG_LOCK);
pfd
will always be null, then you should get the lock screen wallpaper this way: pfd
将永远为null,那么你应该以这种方式得到锁屏壁纸:
if (pfd == null)
pfd = wallpaperManager.getWallpaperFile(WallpaperManager.FLAG_SYSTEM);
you will get the non-null pfd
. 你会得到非null的pfd
。 This is the case no lock-specific wallpaper has been configured.
在这种情况下, no lock-specific wallpaper has been configured.
于no lock-specific wallpaper has been configured.
On the contrary, lock-specific wallpaper has been configured
if you set a photo as lock screen wallpaper directly, wallpaperManager.getWallpaperFile(WallpaperManager.FLAG_SYSTEM)
will return a non-null value. 相反,如果您将照片直接设置为锁定屏幕壁纸, lock-specific wallpaper has been configured
, wallpaperManager.getWallpaperFile(WallpaperManager.FLAG_SYSTEM)
将返回非空值。
So this is the code I use to retrieve the lock screen wallpaper: 所以这是我用来检索锁屏壁纸的代码:
/**
* please check permission outside
* @return Bitmap or Drawable
*/
public static Object getLockScreenWallpaper(Context context)
{
WallpaperManager wallpaperManager = WallpaperManager.getInstance(context);
if (Build.VERSION.SDK_INT >= 24)
{
ParcelFileDescriptor pfd = wallpaperManager.getWallpaperFile(WallpaperManager.FLAG_LOCK);
if (pfd == null)
pfd = wallpaperManager.getWallpaperFile(WallpaperManager.FLAG_SYSTEM);
if (pfd != null)
{
final Bitmap result = BitmapFactory.decodeFileDescriptor(pfd.getFileDescriptor());
try
{
pfd.close();
}
catch (Exception e)
{
e.printStackTrace();
}
return result;
}
}
return wallpaperManager.getDrawable();
}
Don't forget to add READ_EXTERNAL_STORAGE
in the manifest file and grant it outside. 不要忘记在清单文件中添加READ_EXTERNAL_STORAGE
并将其授予外部。
The code I was testing is similar to yours. 我测试的代码与您的代码类似。 I have tested it on Samsung A5 and LG Nexus 5X. 我在三星A5和LG Nexus 5X上测试过它。
MainActivity.java MainActivity.java
import android.Manifest;
import android.annotation.SuppressLint;
import android.app.WallpaperManager;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Build;
import android.os.Bundle;
import android.os.ParcelFileDescriptor;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.widget.ImageView;
public class MainActivity extends AppCompatActivity {
public static final int REQUEST_CODE_EXTERNAL_STORAGE = 5;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
String permission = Manifest.permission.WRITE_EXTERNAL_STORAGE;
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
permission = Manifest.permission.READ_EXTERNAL_STORAGE;
}
if (ContextCompat.checkSelfPermission(this, permission) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, new String[]{permission}, REQUEST_CODE_EXTERNAL_STORAGE);
} else {
retrieveLockScreenWallpaper();
}
}
@Override
public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
switch (requestCode) {
case REQUEST_CODE_EXTERNAL_STORAGE: {
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
retrieveLockScreenWallpaper();
}
}
}
}
@SuppressLint("MissingPermission")
private void retrieveLockScreenWallpaper() {
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.N) {
WallpaperManager manager = WallpaperManager.getInstance(getApplicationContext());
ParcelFileDescriptor descriptor = manager.getWallpaperFile(WallpaperManager.FLAG_LOCK);
if (descriptor != null) {
Bitmap bitmap = BitmapFactory.decodeFileDescriptor(descriptor.getFileDescriptor());
((ImageView) findViewById(R.id.imageView)).setImageBitmap(bitmap);
}
}
}
}
manifest.xml 的manifest.xml
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="aminography.com.lockscreenapplication">
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<application
...
</application>
</manifest>
. 。
Result on LGE Nexus 5X (Android 8.1.0, API 27): 关于LGE Nexus 5X(Android 8.1.0,API 27)的结果:
If no lock-specific wallpaper has been configured for the given user, then this method will return null when requesting FLAG_LOCK rather than returning the system wallpaper's image file. 如果没有为给定用户配置特定于锁的壁纸,则此方法将在请求FLAG_LOCK时返回null,而不是返回系统壁纸的图像文件。
Are you sure you have a valid lock screen wallpaper set for the current user? 您确定为当前用户设置了有效的锁屏壁纸吗?
/**
* Get an open, readable file descriptor to the given wallpaper image file.
* The caller is responsible for closing the file descriptor when done ingesting the file.
*
* <p>If no lock-specific wallpaper has been configured for the given user, then
* this method will return {@code null} when requesting {@link #FLAG_LOCK} rather than
* returning the system wallpaper's image file.
*
* @param which The wallpaper whose image file is to be retrieved. Must be a single
* defined kind of wallpaper, either {@link #FLAG_SYSTEM} or
* {@link #FLAG_LOCK}.
*
* @see #FLAG_LOCK
* @see #FLAG_SYSTEM
*/
public ParcelFileDescriptor getWallpaperFile(@SetWallpaperFlags int which) {
return getWallpaperFile(which, mContext.getUserId());
}
There is a similar function in WallpaperManager openDefaultWallpaper in that if you want LOCK-SCREEN wallpaper you get null, always, as According to the code Factory-default lock wallpapers are not yet supported. 在WallpaperManager openDefaultWallpaper中有一个类似的功能,如果你想要LOCK-SCREEN壁纸你得到null,总是,因为根据代码工厂默认锁定壁纸尚不支持。
So in your case maybe you haven't set the Lock-Screen wallpaper. 所以在你的情况下,你可能还没有设置锁屏壁纸。 Just to test, Download any wallpaper app, and try to set a wallpaper, then use your earlier code, to get it. 只是为了测试,下载任何壁纸应用程序,并尝试设置壁纸,然后使用您之前的代码,以获得它。
/**
* Open stream representing the default static image wallpaper.
*
* If the device defines no default wallpaper of the requested kind,
* {@code null} is returned.
*
* @hide
*/
public static InputStream openDefaultWallpaper(Context context, @SetWallpaperFlags int which) {
final String whichProp;
final int defaultResId;
if (which == FLAG_LOCK) {
/* Factory-default lock wallpapers are not yet supported
whichProp = PROP_LOCK_WALLPAPER;
defaultResId = com.android.internal.R.drawable.default_lock_wallpaper;
*/
return null;
}
You can check the code at : http://androidxref.com/8.1.0_r33/xref/frameworks/base/core/java/android/app/WallpaperManager.java#openDefaultWallpaper 您可以访问以下网址查看代码: http : //androidxref.com/8.1.0_r33/xref/frameworks/base/core/java/android/app/WallpaperManager.java#openDefaultWallpaper
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