WinUI3入门17：本地文件存储LocalApplicationData在哪里
初级代码游戏的专栏介绍与文章目录-CSDN博客
我的github：codetoys，所有代码都将会位于ctfc库中。已经放入库中我会指出在库中的位置。
这些代码大部分以Linux为目标但部分代码是纯C++的，可以在任何平台上使用。
源码指引：github源码指引_初级代码游戏的博客-CSDN博客
C#是我多年以来的业余爱好，新搞的东西能用C#的就用C#了。
如果我们要写入文件，原有的普通目录的文件读写都是没问题的。但是默认位置是不可用的，写入文件“a.txt”会失败，因为默认位置是程序所在位置，这个位置只有系统可以修改。
在新的应用程序管理体系下，程序自己的输出文件可以放在特殊目录LocalApplicationData或ApplicationData下。
目录
一、Windows的特殊目录
二、LocalApplicationData的实际位置
三、代码示例
一、Windows的特殊目录
特殊目录本身并不是新鲜东西，只不过由于安装在程序组下的传统应用可以在程序所在目录下随意修改，所以一般我们并不关注特殊目录。
特殊目录由Environment.SpecialFolder枚举定义（下面的图表来自官方文档）：
| Name | Value | Description |
|---|---|---|
| Desktop | 0 | The logical Desktop rather than the physical file system location. |
| Programs | 2 | The directory that contains the user's program groups. |
| MyDocuments | 5 | The My Documents folder. This member is equivalent to Personal. |
| Personal | 5 | The directory that serves as a common repository for documents. This member is equivalent to MyDocuments. |
| Favorites | 6 | The directory that serves as a common repository for the user's favorite items. |
| Startup | 7 | The directory that corresponds to the user's Startup program group. The system starts these programs whenever a user logs on or starts Windows. |
| Recent | 8 | The directory that contains the user's most recently used documents. |
| SendTo | 9 | The directory that contains the Send To menu items. |
| StartMenu | 11 | The directory that contains the Start menu items. |
| MyMusic | 13 | The My Music folder. |
| MyVideos | 14 | The file system directory that serves as a repository for videos that belong to a user. |
| DesktopDirectory | 16 | The directory used to physically store file objects on the desktop. Do not confuse this directory with the desktop folder itself, which is a virtual folder. |
| MyComputer | 17 | The My Computer folder. When passed to the |
| NetworkShortcuts | 19 | A file system directory that contains the link objects that may exist in the My Network Places virtual folder. |
| Fonts | 20 | A virtual folder that contains fonts. |
| Templates | 21 | The directory that serves as a common repository for document templates. |
| CommonStartMenu | 22 | The file system directory that contains the programs and folders that appear on the Start menu for all users. |
| CommonPrograms | 23 | A folder for components that are shared across applications. |
| CommonStartup | 24 | The file system directory that contains the programs that appear in the Startup folder for all users. |
| CommonDesktopDirectory | 25 | The file system directory that contains files and folders that appear on the desktop for all users. |
| ApplicationData | 26 | The directory that serves as a common repository for application-specific data for the current roaming user. A roaming user works on more than one computer on a network. A roaming user's profile is kept on a server on the network and is loaded onto a system when the user logs on. |
| PrinterShortcuts | 27 | The file system directory that contains the link objects that can exist in the Printers virtual folder. |
| LocalApplicationData | 28 | The directory that serves as a common repository for application-specific data that is used by the current, non-roaming user. |
| InternetCache | 32 | The directory that serves as a common repository for temporary Internet files. |
| Cookies | 33 | The directory that serves as a common repository for Internet cookies. |
| History | 34 | The directory that serves as a common repository for Internet history items. |
| CommonApplicationData | 35 | The directory that serves as a common repository for application-specific data that is used by all users. |
| Windows | 36 | The Windows directory or SYSROOT. This corresponds to the %windir% or %SYSTEMROOT% environment variables. |
| System | 37 | The System directory. |
| ProgramFiles | 38 | The program files directory. In a non-x86 process, passing ProgramFiles to the GetFolderPath(Environment+SpecialFolder) method returns the path for non-x86 programs. To get the x86 program files directory in a non-x86 process, use the ProgramFilesX86 member. |
| MyPictures | 39 | The My Pictures folder. |
| UserProfile | 40 | The user's profile folder. Applications should not create files or folders at this level; they should put their data under the locations referred to by ApplicationData. |
| SystemX86 | 41 | The Windows System folder. |
| ProgramFilesX86 | 42 | The x86 Program Files folder. |
| CommonProgramFiles | 43 | The directory for components that are shared across applications. To get the x86 common program files directory in a non-x86 process, use the ProgramFilesX86 member. |
| CommonProgramFilesX86 | 44 | The Program Files folder. |
| CommonTemplates | 45 | The file system directory that contains the templates that are available to all users. |
| CommonDocuments | 46 | The file system directory that contains documents that are common to all users. |
| CommonAdminTools | 47 | The file system directory that contains administrative tools for all users of the computer. |
| AdminTools | 48 | The file system directory that is used to store administrative tools for an individual user. The Microsoft Management Console (MMC) will save customized consoles to this directory, and it will roam with the user. |
| CommonMusic | 53 | The file system directory that serves as a repository for music files common to all users. |
| CommonPictures | 54 | The file system directory that serves as a repository for image files common to all users. |
| CommonVideos | 55 | The file system directory that serves as a repository for video files common to all users. |
| Resources | 56 | The file system directory that contains resource data. |
| LocalizedResources | 57 | The file system directory that contains localized resource data. |
| CommonOemLinks | 58 | This value is recognized in Windows Vista for backward compatibility, but the special folder itself is no longer used. |
| CDBurning | 59 | The file system directory that acts as a staging area for files waiting to be written to a CD. |
常用的几个：
- Desktop 桌面
- MyDocuments 文档
- ProgramFiles 程序，注意，在x64上有两个目录，这个取64位的
- ProgramFilesX86 程序，用于x64系统上取32位程序的目录，典型是“C:\Program Files (x86)”
- CommonDocuments 公共文档，这个有一些妙处，如果需要多用户交互或者服务和用户交互（服务一般是独立身份，在用户登录之前就启动了），可以通过公共文档进行 （当然，只适合低强度的交互）
- LocalApplicationData 本地程序数据
- ApplicationData 漫游程序数据，会自动多设备同步（具体啥效果没用过）
二、LocalApplicationData的实际位置
传统应用的LocalApplicationData位置是“用户目录\AppData\Local”，一般我们在这下面建立自己的公司目录，公司目录下面建立程序目录。
现代应用中间包了一层，同样的调用并不会返回传统的目录，而是被系统管理的目录（在这个目录里面）：
“用户目录\AppData\Local\Packages\发布者.程序名_长串后缀”
在这个目录下有很多东西：
在这面的“LocalCache\Local”才是LocalApplicationData的实际位置。
三、代码示例
代码很简单，并没有什么不同：
StreamWriter sw = new StreamWriter(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData)+"\\ctDos2Unix.log.txt", true);sw.WriteLine(logitem);sw.Close();
此代码向文件里追加文本，如果文件不存在会创建。
找到位置很难，直接搜文件名就能找到输出位置。
（这里是文档结束）