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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"><title>Introduction</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2"><link rel="start" href="index.html" title="GIO Reference Manual"><link rel="up" href="pt01.html" title="Part I. GIO Overview"><link rel="prev" href="pt01.html" title="Part I. GIO Overview"><link rel="next" href="ch02.html" title="Compiling GIO applications"><meta name="generator" content="GTK-Doc V1.9 (XML mode)"><link rel="stylesheet" href="style.css" type="text/css"><link rel="part" href="pt01.html" title="Part I. GIO Overview"><link rel="chapter" href="ch01.html" title="Introduction"><link rel="chapter" href="ch02.html" title="Compiling GIO applications"><link rel="chapter" href="ch03.html" title="Running GIO applications"><link rel="chapter" href="gio-extension-points.html" title="Extending GIO"><link rel="part" href="pt02.html" title="Part II. API Reference"><link rel="chapter" href="file_ops.html" title="File Operations"><link rel="chapter" href="file_mon.html" title="File System Monitoring"><link rel="chapter" href="async.html" title="Asynchronous I/O"><link rel="chapter" href="streaming.html" title="Streaming I/O"><link rel="chapter" href="types.html" title="File types and applications"><link rel="chapter" href="volume_mon.html" title="Volumes and Drives"><link rel="chapter" href="icons.html" title="Icons"><link rel="chapter" href="utils.html" title="Utilities"><link rel="chapter" href="extending.html" title="Extending GIO"><link rel="part" href="migrating.html" title="Part III. Migrating to GIO"><link rel="chapter" href="ch14.html" title="Migrating from POSIX to GIO"><link rel="chapter" href="ch15.html" title="Migrating from GnomeVFS to GIO"><link rel="chapter" href="gio-hierarchy.html" title="Object Hierarchy"><link rel="index" href="ix01.html" title="Index"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><table class="navigation" id="top" width="100%" summary="Navigation header" cellpadding="2" cellspacing="2"><tr valign="middle"><td><a accesskey="p" href="pt01.html"><img src="left.png" width="24" height="24" border="0" alt="Prev"></a></td><td><a accesskey="u" href="pt01.html"><img src="up.png" width="24" height="24" border="0" alt="Up"></a></td><td><a accesskey="h" href="index.html"><img src="home.png" width="24" height="24" border="0" alt="Home"></a></td><th width="100%" align="center">GIO Reference Manual</th><td><a accesskey="n" href="ch02.html"><img src="right.png" width="24" height="24" border="0" alt="Next"></a></td></tr></table><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id3035396"></a>Introduction</h2></div></div></div><p> GIO is striving to provide a modern, easy-to-use VFS API that sits at the right level in the library stack. The goal is to overcome the shortcomings of GnomeVFS and provide an API that is so good that developers prefer it over raw POSIX calls. Among other things that means using GObject. It also means not cloning the POSIX API, but providing higher-level, document-centric interfaces. </p><p> The abstract file system model of GIO consists of a number of interfaces and base classes for I/O and files: </p><div class="variablelist"><table border="0"><col align="left" valign="top"><tbody><tr><td><p><span class="term">GFile</span></p></td><td><p>reference to a file</p></td></tr><tr><td><p><span class="term">GFileInfo</span></p></td><td><p>information about a file or filesystem</p></td></tr><tr><td><p><span class="term">GFileEnumerator</span></p></td><td><p>list files in directories</p></td></tr><tr><td><p><span class="term">GDrive</span></p></td><td><p>represents a drive</p></td></tr><tr><td><p><span class="term">GVolume</span></p></td><td><p>represents a file system in an abstract way</p></td></tr><tr><td><p><span class="term">GMount</span></p></td><td><p>represents a mounted file system</p></td></tr></tbody></table></div><p> Then there is a number of stream classes, similar to the input and output stream hierarchies that can be found in frameworks like Java: </p><div class="variablelist"><table border="0"><col align="left" valign="top"><tbody><tr><td><p><span class="term">GInputStream</span></p></td><td><p>read data</p></td></tr><tr><td><p><span class="term">GOutputStream</span></p></td><td><p>write data</p></td></tr><tr><td><p><span class="term">GSeekable</span></p></td><td><p>interface optionally implemented by streams to support seeking</p></td></tr></tbody></table></div><p> There are interfaces related to applications and the types of files they handle: </p><div class="variablelist"><table border="0"><col align="left" valign="top"><tbody><tr><td><p><span class="term">GAppInfo</span></p></td><td><p>information about an installed application</p></td></tr><tr><td><p><span class="term">GIcon</span></p></td><td><p>abstract type for file and application icons</p></td></tr></tbody></table></div><p> Beyond these, GIO provides facilities for file monitoring, asynchronous I/O and filename completion. In addition to the interfaces, GIO provides implementations for the local case. Implementations for various network file systems are provided by the GVFS package as loadable modules. </p><p> Other design choices which consciously break with the GnomeVFS design are to move backends out-of-process, which minimizes the dependency bloat and makes the whole system more robust. The backends are not included in GIO, but in the separate GVFS package. The GVFS package also contains the GVFS daemon, which spawn further mount daemons for each individual connection. </p><div class="figure"><a name="gvfs-overview"></a><p class="title"><b>Figure 1. GIO in the GTK+ library stack</b></p><div class="figure-contents"><div><img src="gvfs-overview.png" alt="GIO in the GTK+ library stack"></div></div></div><br class="figure-break"><p> The GIO model of I/O is stateful: if an application establishes e.g. a SFTP connection to a server, it becomes available to all applications in the session; the user does not have to enter his password over and over again. </p><p> One of the big advantages of putting the VFS in the GLib layer is that GTK+ can directly use it, e.g. in the filechooser. </p></div></body></html>⌨️ 快捷键说明
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