managedQuery() vs context.getContentResolver.query() vs android.provider.something.query()
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managedQuery() vs context.getContentResolver.query() vs android.provider.something.query()
提问by Macarse
Pretty simple. What is the difference among those three?
很简单。这三者有什么区别？
I want to list every Image in a device.
Should I use managedQuery(), android.provider.MediaStore.Images.Media.query()or context.getContentResolver.query()
我想列出设备中的每个图像。我应该使用managedQuery(),android.provider.MediaStore.Images.Media.query()还是context.getContentResolver.query()
回答by Pentium10
managedQuery()will use ContentResolver's query(). The difference is
that with managedQuery()the activity will keep a reference to your
Cursor and close it whenever needed (in onDestroy()for instance.) If
you do query()yourself, you willhave to manage the Cursor as a
sensitive resource. If you forget, for instance, to close()it in
onDestroy(), you will leak underlying resources (logcat will warn you
about it.)
managedQuery()将使用 ContentResolver 的 query()。不同之处在于managedQuery()活动将保留对您的 Cursor 的引用并在需要时关闭它（onDestroy()例如）。如果您query()自己做，您将不得不将 Cursor 作为敏感资源进行管理。例如，如果你忘记了close()它
onDestroy()，你将泄漏底层资源（logcat 会警告你。）
To query a content provider, you can use either the ContentResolver.query()method or the Activity.managedQuery()method. Both methods take the same set of arguments, and both return a Cursor object. However, managedQuery()causes the activity to manage the life cycle of the Cursor. A managed Cursor handles all of the niceties, such as unloading itself when the activity pauses, and requerying itself when the activity restarts. You can ask an Activity to begin managing an unmanaged Cursor object for you by calling Activity.startManagingCursor().
要查询内容提供者，您可以使用ContentResolver.query()方法或Activity.managedQuery()方法。这两种方法都采用相同的参数集，并且都返回一个 Cursor 对象。但是，managedQuery()导致活动管理光标的生命周期。托管 Cursor 处理所有细节，例如在 Activity 暂停时卸载自身，以及在 Activity 重新启动时重新查询自身。您可以通过调用 来让 Activity 开始为您管理非托管 Cursor 对象Activity.startManagingCursor()。
Update:
更新：
managedQueryis now deprecated (as of Android 3.0).
managedQuery现在已弃用（从 Android 3.0 开始）。
回答by user979247
managedQuery(..) is now deprecated (as of Android 3.0). Watch out..
managedQuery(..) 现在已弃用（从 Android 3.0 开始）。小心..
Android error: java.lang.IllegalStateException: trying to requery an already closed cursor
