[英]Reset Application setting in wp7
我创建了一个应用程序,该应用程序最初创建数据库并在其中保存一些数据。 现在,我想在用户单击“重置”按钮时删除此数据库及其文件,但出现错误–“此操作正在另一进程中使用”。 单击重置按钮时,我希望它删除并重新创建数据库。 有任何想法吗?
最常见的原因是与Windows Phone上的隔离存储进行交互的线程不安全特性。 无论您如何实现数据库(在一个文件或一系列文件中),都在某种程度上与隔离存储进行交互。
我强烈建议您阅读,并确保您在开始之前了解一下隔离存储的概述 。
您备注:
这是在另一个过程中使用的
让我觉得您正在使用第三方库来完成数据库工作。 当库本身无法访问隔离存储时,将引发此异常/错误。 在不确切知道如何实现数据库的情况下,很难准确地说明自己的情况。
您永远不会“重新创建IsolatedStorage”,Isolated Storage是一个术语,用于定义您的应用程序可以访问的磁盘空间的集合。 就像文件夹一样,该磁盘空间具有根目录,并且仅包含您创建的文件。
为了避免在访问隔离存储时出现线程异常,请确保在C#中使用using关键字,如下所示:
namespace IsolatedStorageExample
{
public class ISOAccess
{
// This example method will read a file inside your Isolated Storage.
public static String ReadFile(string filename)
{
string fileContents = "";
// Ideally, you should enclose this entire next section in a try/catch block since
// if there is anything wrong with below, it will crash your app.
//
// This line returns the "handle" to your Isolated Storage. The phone considers the
// entire isolated storage folder as a single "file", which is why it can be a
// little bit of a confusing name.
using(IsolatedStorageFile file = IsolatedStorageFile.GetUserStoreForAppliaction())
{
// If the file does not exist, return an empty string
if(file.Exists(filename))
{
// Obtain a stream to the file
using(IsolatedStorageFileStream stream = File.OpenFile(filename, FileMode.Open)
{
// Open a stream reader to actually read the file.
using(StreamReader reader = new StreamReader(stream))
{
fileContents = reader.ReadToEnd();
}
}
}
}
return fileContents;
}
}
}
那应该有助于解决线程安全性问题。 为了更具体地帮助您实现目标,请看一下以下方法(您可以将其添加到上面的类中):
// BE VERY CAREFUL, running this method will delete *all* the files in isolated storage... ALL OF THEM
public static void ClearAllIsolatedStorage()
{
// get the handle to isolated storage
using(IsolatedStorageFile file = IsolatedStorageFile.GetUserStoreForApplication())
{
// Get a list of all the folders in the root directory
Queue<String> rootFolders = new Queue<String>(file.GetDirectoryNames());
// For each folder...
while(0 != rootFolders.Count)
{
string folderName = rootFolders.Dequeue();
// First, recursively delete all the files and folders inside the given folder.
// This is required, because you cannot delete a non-empty directory
DeleteFilesInFolderRecursively(file, folderName);
// Now that all of it's contents have been deleted, you can delete the directory
// itsself.
file.DeleteDirectory(rootFolders.Dequeue());
}
// And now we delete all the files in the root directory
Queue<String> rootFiles = new Queue<String>(file.GetFileNames());
while(0 != rootFiles.Count)
file.DeleteFile(rootFiles.Dequeue());
}
}
private static void DeleteFilesInFolderRecursively(IsolatedStorageFile iso, string directory)
{
// get the folders that are inside this folder
Queue<string> enclosedDirectories = new Queue<string>(iso.GetDirectoryNames(directory));
// loop through all the folders inside this folder, and recurse on all of them
while(0 != enclosedDirectories.Count)
{
string nextFolderPath = Path.Combine(directory, enclosedDirectories.Dequeue());
DeleteFilesInFolderRecursively(nextFolderPath);
}
// This string will allow you to see all the files in this folder.
string fileSearch = Path.Combine(directory, "*");
// Getting the files in this folder
Queue<string> filesInDirectory = iso.GetFileNames(fileSearch);
// Finally, deleting all the files in this folder
while(0 != filesInDirectory.Count)
{
iso.DeleteFile(filesInDirectory.Dequeue());
}
}
我强烈建议的另一件事是实现使用“多线程单例模式”来访问IsolatedStorage的类,如此处所述。
希望对您有所帮助。 代码是“按原样”提供的,我没有编译它,但是一般概念都存在,因此,如果有什么不对,请阅读MSDN文档,以了解有什么不对劲的地方。 但我向您保证,大部分代码都是从我的功能代码复制而来的,因此它应该可以在很少幻想的情况下正常运行。
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