Windows 8学习笔记(四)--Storage数据存储

AppData在Metro App中的存储主要由两种形式，一种是键值对的形式，还有一种是StorageFile文件的存储形式。

其中键值对形式的存储又分几种：ApplicationDataCompositeValue复合值存储、ApplicationDataContainer容器数据存储、ApplicationDataContainerSettings普通的容器数据存储。

注意这种键值对的存储值只能以字符形式存储，若要存储某对象，需转成XML或json等其它字符数据。

ApplicationDataCompositeValue的用法

支持复合值的存储

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Windows.Storage.ApplicationDataContainer localSettings = Windows.Storage.ApplicationData.Current.LocalSettings;    // Create a composite setting                Windows.Storage.ApplicationDataCompositeValue composite = new Windows.Storage.ApplicationDataCompositeValue(); composite[ "intVal" ] = 1; composite[ "strVal" ] = "string" ;   localSettings.Values[ "exampleCompositeSetting" ] = composite;   // Read data from a composite settingWindows.Storage.ApplicationDataCompositeValue composite = (Windows.Storage.ApplicationDataCompositeValue)localSettings.Values["exampleCompositeSetting"];                    // Delete a composite setting localSettings.Values.Remove( "exampleCompositeSetting" );

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 ApplicationDataContainer的用法

　支持创建、删除、枚举、数据容器层次的贯穿

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Windows.Storage.ApplicationDataContainer localSettings = Windows.Storage.ApplicationData.Current.LocalSettings; // Create a setting in a container Windows.Storage.ApplicationDataContainer container =     localSettings.CreateContainer( "exampleContainer" , Windows.Storage.ApplicationDataCreateDisposition.Always); if (localSettings.Containers.ContainsKey( "exampleContainer" )) {     localSettings.Containers[ "exampleContainer" ].Values[ "exampleSetting" ] = "Hello Windows" ; } // Read data from a setting in a container bool hasContainer = localSettings.Containers.ContainsKey( "exampleContainer" ); bool hasSetting = false ; if (hasContainer) {     hasSetting = localSettings.Containers[ "exampleContainer" ].Values.ContainsKey( "exampleSetting" ); } // Delete a container localSettings.DeleteContainer( "exampleContainer" );

 

 ApplicationDataContainerSettings的用法

　最简单的键值对存储

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var localSettings = Windows.Storage.ApplicationData.Current.LocalSettings;       // Create a simple setting localSettings.Values[ "exampleSetting" ] = "Hello Windows 8" ;       if (localSettings.Values.ContainsKey( "exampleSetting" ))    {         // Read data from a simple setting         Object value = localSettings.Values[ "exampleSetting" ];        }                 localSettings.Values.Remove( "exampleSetting" );

 

StorageFile的存储，以文件的形式进行存储

存入数据

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static async public Task SaveAsync<t>(T data, string fileName)          {              // Get the output stream for the SessionState file.              StorageFile file = await ApplicationData.Current.LocalFolder.CreateFileAsync(fileName, CreationCollisionOption.ReplaceExisting);              IRandomAccessStream raStream = await file.OpenAsync(FileAccessMode.ReadWrite);              using (IOutputStream outStream = raStream.GetOutputStreamAt(0))              {                  // Serialize the Session State.                                    DataContractSerializer serializer = new DataContractSerializer( typeof (T));                  serializer.WriteObject(outStream.AsStreamForWrite(), data);                  await outStream.FlushAsync();              }          }</t>

 

取文件数据

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static async public Task<t> RestoreAsync<t>( string filename)          {              // Get the input stream for the SessionState file.              T sessionState_ = default (T);              try              {                  StorageFile file = await ApplicationData.Current.LocalFolder.GetFileAsync(filename);                  if (file == null ) return sessionState_;                  IInputStream inStream = await file.OpenSequentialReadAsync();                  // Deserialize the Session State.                  DataContractSerializer serializer = new DataContractSerializer( typeof (T));                                 sessionState_= (T)serializer.ReadObject(inStream.AsStreamForRead());                             }              catch (Exception)              {                  // Restoring state is best-effort.  If it fails, the app will just come up with a new session.                                }              return sessionState_;          }</t></t>

以上就是Metro Style App中数据存储的几种方式，怎么样，跟Windows Phone7中还是有些差别的吧。。。

 

顺便整理一下xml/json格式数据的序列与反序列化的通用方法

JSON数据的序列与反序列

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public static T DataContractJsonDeSerializer<t>( string jsonString)          {              var ds = new DataContractJsonSerializer( typeof (T));              var ms = new MemoryStream(Encoding.UTF8.GetBytes(jsonString));              T obj = (T)ds.ReadObject(ms);              ms.Dispose();              return obj;          }            public static string ToJsonData( object item)          {              DataContractJsonSerializer serializer = new DataContractJsonSerializer(item.GetType());              string result = String.Empty;              using (MemoryStream ms = new MemoryStream())              {                  serializer.WriteObject(ms, item);                  ms.Position = 0;                  using (StreamReader reader = new StreamReader(ms))                  {                      result = reader.ReadToEnd();                  }              }              return result;          }</t>

XML数据的序列与反序列

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/// <summary>

         /// 需要序列化XML数据对象

         /// </summary>

         /// <param name="objectToSerialize"><returns></returns>

         public static string XMLSerialize( object objectToSerialize)

         {

             string result = "" ;

             using (MemoryStream ms = new MemoryStream())

             {

                 DataContractSerializer serializer = new DataContractSerializer(objectToSerialize.GetType());

                 serializer.WriteObject(ms, objectToSerialize);

                 ms.Position = 0;

 

                 using (StreamReader reader = new StreamReader(ms))

                 {

                     result = reader.ReadToEnd();

                 }

             }

             return result;

         }

        

         /// <summary>

         /// XML数据反序列化

         /// </summary>

         /// <typeparam name="T">反序列化对象</typeparam>

         /// <param name="xmlstr"><returns></returns>

         public static T XMLDeserialize<t>( string xmlstr)

         {

             byte [] newBuffer = System.Text.Encoding.UTF8.GetBytes(xmlstr);

 

             if (newBuffer.Length == 0)

             {

                 return default (T);

             }

             using (MemoryStream ms = new MemoryStream(newBuffer))

             {

                 DataContractSerializer serializer = new DataContractSerializer( typeof (T));

                 return (T)serializer.ReadObject(ms);

             }

         }</t>

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http://www.cnblogs.com/jing870812/archive/2012/04/05/2433753.html

转载于:https://www.cnblogs.com/hdjjun/archive/2012/07/03/2574945.html