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ContentResolverCompat

public final class ContentResolverCompat
extends Object

java.lang.Object
   ↳ android.support.v4.content.ContentResolverCompat

Helper用于访问以向后兼容的方式在API级别4之后引入的 ContentResolver功能。

Summary

Public methods
static Cursor query(ContentResolver resolver, Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder, CancellationSignal cancellationSignal)

查询给定的URI，在结果集上返回一个 Cursor ，并带有可选的支持取消。

Inherited methods
From class java.lang.Object

Public methods

query

Cursor query (ContentResolver resolver, 
                Uri uri, 
                String[] projection, 
                String selection, 
                String[] selectionArgs, 
                String sortOrder, 
                CancellationSignal cancellationSignal)

查询给定的URI，在结果集上返回 Cursor ，并带有可选的支持取消。

为获得最佳性能，来电者应遵循以下准则：

  • Provide an explicit projection, to prevent reading data from storage that aren't going to be used.
  • Use question mark parameter markers such as 'phone=?' instead of explicit values in the selection parameter, so that queries that differ only by those values will be recognized as the same for caching purposes.

Parameters
resolver ContentResolver
uri Uri: The URI, using the content:// scheme, for the content to retrieve.
projection String: A list of which columns to return. Passing null will return all columns, which is inefficient.
selection String: A filter declaring which rows to return, formatted as an SQL WHERE clause (excluding the WHERE itself). Passing null will return all rows for the given URI.
selectionArgs String: You may include ?s in selection, which will be replaced by the values from selectionArgs, in the order that they appear in the selection. The values will be bound as Strings.
sortOrder String: How to order the rows, formatted as an SQL ORDER BY clause (excluding the ORDER BY itself). Passing null will use the default sort order, which may be unordered.
cancellationSignal CancellationSignal: A signal to cancel the operation in progress, or null if none. If the operation is canceled, then OperationCanceledException will be thrown when the query is executed.
Returns
Cursor A Cursor object, which is positioned before the first entry, or null

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