从应用专用存储共享图像到Facebook [英] Sharing image from app private storage to Facebook

问题描述

我试图采取一种非常通用的方法来提供共享选项，从我的应用程序的私人存储共享图像，但我遇到了一个问题，似乎是特定于共享图像到Facebook应用程序（com.facebook。 katana）：

1. 我将包含Uri的EXTRA_STREAM的意图发送到我应用程序私有目录中的图像。



2. 通过ContentProvider，我可以通过在 openFile（）中返回以下内容来提供对所需文件的访问：

     return ParcelFileDescriptor.open（file，ParcelFileDescriptor.MODE_READ_ONLY）; 
     




3. 分享到Facebook时，图像不会显示。然而，每个其他应用程序都可以正常工作将调用调用到我的ContentProvider，我看到Facebook确实查询了ContentProvider，并且 openFile（）被命中。不过，图像不会出现。

解决方案

，我意识到我正在返回 null 作为MIME类型。我改变了 getType（）的结果返回image / png，就是这样：Facebook接受了我的形象：

  @Nullable 
 @Override 
 public String getType（@NonNull Uri uri）{
 //绝对必须提供MIME类型否则一些应用程序，如
 // Facebook将简单地忽略该文件
 returnimage / png; 
} 
  

我会指出你应该返回实际的MIME类型与Uri相关联的文件;我在这里返回PNG，因为我很懒，我知道我的所有图像都是这种类型。

I'm attempting to take a very generic approach in providing sharing options for sharing images from my app's private storage, but I've encountered a problem that appears to be specific to sharing images to the Facebook app (com.facebook.katana):

1. I launch an intent with EXTRA_STREAM containing a Uri to an image inside the private directory of my app.

2. Through a ContentProvider, I provide access to the desired file by returning the following in openFile():

   return ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY);
   

3. When sharing to Facebook, the image doesn't appear. Every other app, however, does work. Debugging calls into my ContentProvider, I see that Facebook does indeed query the ContentProvider, and openFile() is hit. Nevertheless, the image doesn't appear.

解决方案

After much head scratching, I realized I was returning null as the MIME type. I changed the result of getType() to return "image/png", and that was it: Facebook accepted my image:

@Nullable
@Override
public String getType(@NonNull Uri uri) {
    // It's absolutely imperative that we provide the MIME type, otherwise some apps like
    // Facebook will simply ignore the file
    return "image/png";
}

I would point out that you should return the actual MIME type of the file associated with the Uri; I'm returning PNG here because I'm lazy, and I know that all my images are of that type.

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