ILockBytes

Windows Mobile 6.5 https://msdn.microsoft.com/zh-cn/library/aa911496(en-us,MSDN.10).aspx

這個(gè)接口是一個(gè)字節(jié)數(shù)組對(duì)象上實(shí)現(xiàn)由一些物理存儲(chǔ),如磁盤(pán)文件,全局內(nèi)存或數(shù)據(jù)庫(kù)。

它使用一個(gè)組件對(duì)象模型(COM)復(fù)合文件存儲(chǔ)對(duì)象給其根存儲(chǔ)訪問(wèn)物理設(shè)備,而隔離根存儲(chǔ)訪問(wèn)物理存儲(chǔ)的細(xì)節(jié)。

什么時(shí)候?qū)崿F(xiàn)

大多數(shù)應(yīng)用程序不會(huì)實(shí)現(xiàn)?ILockBytes?因?yàn)镃OM接口提供了實(shí)現(xiàn)最常見(jiàn)的一種情況:

基于文件的實(shí)現(xiàn)?如果你所說(shuō)的?StgCreateDocfile?函數(shù)創(chuàng)建一個(gè)復(fù)合文件存儲(chǔ)對(duì)象,它包含的一個(gè)實(shí)現(xiàn)ILockBytes?這是關(guān)聯(lián)到一個(gè)字節(jié)數(shù)組存儲(chǔ)在一個(gè)物理磁盤(pán)文件。

復(fù)合文件存儲(chǔ)對(duì)象調(diào)用?ILockBytes?方法。 你不叫他們直接在這個(gè)實(shí)現(xiàn)。

有些情況下,這將是有用的為應(yīng)用程序提供它自己的?ILockBytes?實(shí)現(xiàn)。

例如,一個(gè)數(shù)據(jù)庫(kù)應(yīng)用程序可以實(shí)現(xiàn)?ILockBytes?創(chuàng)建一個(gè)字節(jié)數(shù)組對(duì)象支持的存儲(chǔ)的關(guān)系表。 然而,強(qiáng)烈建議您使用COM-provided實(shí)現(xiàn)。

討論了使用COM實(shí)現(xiàn)的優(yōu)點(diǎn),而不是創(chuàng)建自己的看到?StgCreateDocfileOnILockBytes?函數(shù),它創(chuàng)建了一個(gè)復(fù)合文件存儲(chǔ)對(duì)象的調(diào)用者提供的字節(jié)數(shù)組對(duì)象。

什么時(shí)候使用

的?ILockBytes?COM的實(shí)現(xiàn)方法?IStorage?和?IStream?復(fù)合文件對(duì)象的接口。

除非你正在實(shí)施?IStorage?和?IStream?,你不需要打電話?ILockBytes?直接的方法。

如果你寫(xiě)你自己的?ILockBytes?實(shí)現(xiàn),您可以使用?StgCreateDocfileOnILockBytes?函數(shù)創(chuàng)建一個(gè)復(fù)合文件存儲(chǔ)對(duì)象支持的實(shí)現(xiàn)?ILockBytes?。

方法

下面的表顯示了這個(gè)接口的方法按字母順序排列的。

?

方法描述

沖洗	確保維護(hù)的任何內(nèi)部緩沖區(qū)字節(jié)數(shù)組對(duì)象寫(xiě)入到存儲(chǔ)支持。
LockRegion	限制訪問(wèn)指定范圍的字節(jié)數(shù)組。
ReadAt	讀取指定的字節(jié)數(shù)在指定偏移位置開(kāi)始從一開(kāi)始的數(shù)組。
SetSize	字節(jié)數(shù)組的大小變化。
統(tǒng)計(jì)	檢索?STATSTG?這個(gè)字節(jié)數(shù)組對(duì)象結(jié)構(gòu)。
UnlockRegion	刪除之前限制的訪問(wèn)限制在一個(gè)范圍的字節(jié)?ILockBytes:LocRegion?。
WriteAt	寫(xiě)入指定數(shù)量的字節(jié)數(shù)組中指定的位置。

講話

確定平臺(tái)是否支持這個(gè)接口,明白了?Determining Supported COM APIs.

Requirements

Header	objidl.h, objidl.idl
Library	ole32.lib, uuid.lib
Windows Embedded CE	Windows CE 2.0 and later
Windows Mobile	Windows Mobile Version 5.0 and later

?

This interface is implemented on a byte array object that is backed by some physical storage, such as a disk file, global memory, or a database.

It is used by a Component Object Model (COM) compound file storage object to give its root storage access to the physical device, while isolating the root storage from the details of accessing the physical storage.

When to Implement

Most applications will not implement the?ILockBytes?interface because COM provides implementations for one of the most common situations:

File-based implementation?If you call the?StgCreateDocfile?function to create a compound file storage object, it contains an implementation of?ILockBytes?that is associated with a byte array stored in a physical disk file.

The compound file storage object calls the?ILockBytes?methods. You do not call them directly in this implementation.

There are situations in which it would be useful for an application to provide its own?ILockBytes?implementation.

For example, a database application could implement?ILockBytes?to create a byte array object backed by the storage of its relational tables. However, it is strongly recommended that you use the COM-provided implementations.

For a discussion of the advantages of using the COM implementations rather than creating your own, see the?StgCreateDocfileOnILockBytes?function, which creates a compound file storage object on top of a caller-provided byte array object.

When to Use

The?ILockBytes?methods are called by the COM implementations of the?IStorage?and?IStream?interfaces on the compound file object.

Unless you are implementing?IStorage?and?IStream, you would not need to call?ILockBytes?methods directly.

If you write your own?ILockBytes?implementation, you can use the?StgCreateDocfileOnILockBytes?function to create a compound file storage object backed by your implementation of?ILockBytes.

Methods

The following table shows the methods for this interface in alphabetical order.

?

MethodDescription

Flush	Ensures that any internal buffers maintained by the byte array object are written out to the backing storage.
LockRegion	Restricts access to a specified range of bytes in the array.
ReadAt	Reads a specified number of bytes starting at a specified offset from the beginning of the array.
SetSize	Changes the size of the byte array.
Stat	Retrieves a?STATSTG?structure for this byte array object.
UnlockRegion	Removes the access restriction on a range of bytes previously restricted with?ILockBytes::LocRegion.
WriteAt	Writes a specified number of bytes to a specified location in the array.

Remarks

To determine whether the platform supports this interface, see?Determining Supported COM APIs.

Requirements

Header	objidl.h, objidl.idl
Library	ole32.lib, uuid.lib
Windows Embedded CE	Windows CE 2.0 and later
Windows Mobile	Windows Mobile Version 5.0 and later

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