IStorage

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 IStorage 接口支持结构化存储对象的创建和管理。 结构化存储允许分层存储在单个文件的信息,和通常被称为“文件系统内文件”。 元素的结构化存储对象存储和小溪。 存储类似于目录,和流类似于文件。 在一个结构化的存储将会有一个可能包含substorages主存储对象,可能是嵌套的,和小溪。 存储提供对象的结构,包含数据流,通过操纵 IStream 接口。

的 IStorage 接口提供了创建和管理方法根存储对象,孩子存储对象,和流对象。 这些方法可以创建、开放、枚举、移动、复制、重命名或删除元素存储对象。

应用程序必须释放它 IStorage 指针完成时所使用的存储对象来释放内存。 也有一些方法来改变一个元素的日期和时间。

有许多不同的模式的一个存储对象及其元素可以打开,通过设置值决定 STGM常量 。 这就是变化的一个方面。 你可以设置直接模式,改变一个对象会立即写,或交易模式,更改写入缓冲区,直到明确承诺。 的IStorage 接口提供了方法提交更改,并恢复到最后一次提交的版本。 例如,可以在只读模式下打开一个流或读/写模式。 有关更多信息,请参见 STGM常量 。

其他方法提供的信息通过一个存储对象及其元素 STATSTG 结构。

什么时候实现

一般来说,你不会实现这个接口,除非你是定义一个新的存储系统方案。 COM提供了一个复合文件的实现 IStorage 界面,支持事务访问。 COM提供了一组helper api来促进使用复合文件存储对象的实现。 有关更多信息,请参见 IStorage -复合文件实现 。

什么时候使用

调用的方法 IStorage 在当前的存储管理substorages或流。 这种管理包括创建、打开或破坏substorages流,以及管理等方面的时间邮票,名称,等等。 你也可以提交修改或恢复到以前的版本存储在交易模式下打开。 的方法 IStorage 不包括意味着读写蠕升是预留给 IStream 管理实际的数据。 而 IStorage 和 IStream 接口是用来操作存储对象和它的元素, IPersistStorage 接口包含方法称为序列化存储对象及其元素到磁盘上的一个文件里。

成员

的 IStorage 接口继承自 IUnknown 接口。 IStorage 也有这些类型的成员:

• 方法

方法

的 IStorage 接口有这些方法。

需求

See also

The IStorage interface supports the creation and management of structured storage objects. Structured storage allows hierarchical storage of information within a single file, and is often referred to as "a file system within a file". Elements of a structured storage object are storages and streams. Storages are analogous to directories, and streams are analogous to files. Within a structured storage there will be a primary storage object that may contain substorages, possibly nested, and streams. Storages provide the structure of the object, and streams contain the data, which is manipulated through the IStream interface.

The IStorage interface provides methods for creating and managing the root storage object, child storage objects, and stream objects. These methods can create, open, enumerate, move, copy, rename, or delete the elements in the storage object.

An application must release its IStorage pointers when it is done with the storage object to deallocate memory used. There are also methods for changing the date and time of an element.

There are a number of different modes in which a storage object and its elements can be opened, determined by setting values from STGM Constants. One aspect of this is how changes are committed. You can set direct mode, in which changes to an object are immediately written to it, or transacted mode, in which changes are written to a buffer until explicitly committed. The IStorage interface provides methods for committing changes and reverting to the last-committed version. For example, a stream can be opened in read-only mode or read/write mode. For more information, see STGM Constants.

Other methods provide access to information about a storage object and its elements through the STATSTG structure.

When to implement

Generally, you would not implement this interface unless you were defining a new storage scheme for your system. COM provides a compound file implementation of the IStorage interface that supports transacted access. COM provides a set of helper APIs to facilitate using the compound file implementation of storage objects. For more information, see IStorage - Compound File Implementation.

When to use

Call the methods of IStorage to manage substorages or streams within the current storage. This management includes creating, opening, or destroying substorages or streams, as well as managing aspects such as time stamps, names, and so forth. You also can commit changes or revert to previous version for storages opened in transacted mode. The methods of IStorage do not include means to read and write data—this is reserved for IStream, which manages the actual data. While the IStorage and IStream interfaces are used to manipulate the storage object and its elements, the IPersistStorage interface contains methods that are called to serialize the storage object and its elements to a disk file.

Members

The IStorage interface inherits from the IUnknown interface. IStorage also has these types of members:

• Methods

Methods

The IStorage interface has these methods.

Requirements

See also

IStorage

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原文地址：http://www.cnblogs.com/endv/p/6786028.html