silverlight的独立存储

这个东西有点象Flash的Cookie,可以用来在客户端存储一些数据，我在官方文档上读到这个功能的第一反应就是:用它来做IM的客户端聊天记录存储太棒了，呵呵

这里把官方文档上的示例精减整理了一下，贴在这里纪念

先引用
using System.IO.IsolatedStorage;
using System.IO;

下面的代码展示了，如何在存储区创建目录/文件，以及如何写入文件，读取文件

 1 try
 2              {
 3                using (var store = IsolatedStorageFile.GetUserStoreForApplication())
 4                {
 5                    
 6                    StringBuilder sb = new StringBuilder();
 7                   //创建主目录
 8                    store.CreateDirectory("MainDir1");
 9
10
11                    //在MainDir1下创建子目录SubDir1
12                    string subdirectory1 = Path.Combine("MainDir1", "SubDir1");
13                    store.CreateDirectory(subdirectory1);
14
15
16                    //在SubDir1目录下创建文本文件demo.txt
17                    IsolatedStorageFileStream subDirFile = store.CreateFile(Path.Combine(subdirectory1, "demo.txt"));
18                    subDirFile.Close();
19
20                    string filePath = Path.Combine(subdirectory1, "demo.txt");
21                    if (store.FileExists(filePath))
22                    {
23                        try
24                        {
25                            using (StreamWriter sw = new StreamWriter(store.OpenFile(filePath, FileMode.Open, FileAccess.Write)))
26                            {
27                                sw.WriteLine("To do list:");
28                                sw.WriteLine("1. Buy supplies.");
29                            }
30                        }
31                        catch (IsolatedStorageException ex)
32                        {
33                            sb.AppendLine(ex.Message);
34                        }
35                    }
36
37                    // 读取文件 MainDir1\SubDir1\demo.txt
38                    try
39                    {
40                        using (StreamReader reader = new StreamReader(store.OpenFile(filePath,FileMode.Open, FileAccess.Read)))
41                        {
42                            string contents = reader.ReadToEnd();
43                            sb.AppendLine(filePath + " contents:");
44                            sb.AppendLine(contents);
45                        }
46                    }
47                    catch (IsolatedStorageException ex)
48                    {
49
50                        sb.AppendLine(ex.Message);
51                    }
52
53                    //删除文件
54                    try
55                    {
56                        if (store.FileExists(filePath))
57                        {
58                            store.DeleteFile(filePath);
59                        }
60                    }
61                    catch (IsolatedStorageException ex)
62                    {
63                        sb.AppendLine(ex.Message);
64                    }
65
66
67                    //移除store
68                    store.Remove();
69
70                    sb.AppendLine("Store removed.");
71
72                    txtParam.Text = sb.ToString();
73                }
74            }
75              catch  (IsolatedStorageException ex)
76              {
77                txtParam.Text = ex.Message.ToString();
78
79            }

存储区的默认大小是100K,如果感觉不够用了，可以用下面的代码向用户申请扩大:

 1 //  Obtain an isolated store for an application.
 2              try
 3              {
 4                using (var store = IsolatedStorageFile.GetUserStoreForApplication())
 5                {
 6                    // Request 5MB more space in bytes.
 7                    Int64 spaceToAdd = 52428800;
 8                    Int64 curAvail = store.AvailableFreeSpace;
 9
10                    // If available space is less than
11                    // what is requested, try to increase.
12                    if (curAvail < spaceToAdd)
13                    {
14
15                        // Request more quota space.
16                        if (!store.IncreaseQuotaTo(store.Quota + spaceToAdd))
17                        {
18                            // The user clicked NO to the
19                            // host's prompt to approve the quota increase.
20                        }
21                        else
22                        {
23                            // The user clicked YES to the
24                            // host's prompt to approve the quota increase.
25                        }
26                    }
27                }
28            }
29
30              catch  (IsolatedStorageException)
31              {
32                // TODO: Handle that store could not be accessed.
33
34            }

想知道存储区的空间使用情况吗？

 1 //  Obtain an isolated store for an application.
 2              try
 3              {
 4                using (var store = IsolatedStorageFile.GetUserStoreForApplication())
 5                {
 6                    string spaceUsed = (store.Quota - store.AvailableFreeSpace).ToString();
 7                    string spaceAvailable = store.AvailableFreeSpace.ToString();
 8                    string curQuota = store.Quota.ToString();
 9                    txtParam.Text =
10                        String.Format("Quota: {0} bytes, Used: {1} bytes, Available: {2} bytes",
11                                curQuota, spaceUsed, spaceAvailable);
12                }
13            }
14
15              catch  (IsolatedStorageException)
16              {
17                txtParam.Text = "Unable to access store.";
18
19            }