自定义扩展Provider当然要有自己的配制文件,在上一编文章中我们介绍了文件CommunityServer.config,在CORE节点我们可找到<provider>节点,这个配制,今天我们来看看从读取到实现的整个过程.当然我们的程序可能只有个别Provider需要扩展就不需要自己配制一个文件,我们可以通过在Web.config文件中配制一个节点用来存储Provider或直接放在<appSettings>中.
下面我们来看看provider的配制文件:
PROVIDER
1
<providers>
2
3 <clear/>
4 <!--
5 SqlForumsProvider :
6 Microsoft(r)'s SQL Server Data Provider Configuration Section
7
8 To configure manually, replace the value for connectionString with
9 your MSSQLSERVER's connect information.
10
11 For example, replace:
12 connectionString = "-SqlConnectiongString-"
13 with:
14 connectionString = "server=127.0.0.1;database=CommunityServer;uid=Username;pwd=Password"
15
16
17 If installing into a shared web hosting company's database, you will most likely be installing from a
18 non-DBO (DataBase Owner) account. To ensure your database objects can be accessed properly from the forums,
19 you may need to change the databaseOwner value below to your username/accoutname you have with your hosting company.
20
21 For example, replace:
22 databaseOwner = "dbo"
23 with:
24 databaseOwner = "Username"
25 -->
26 <add
27 name = "CommonDataProvider"
28 type = "CommunityServer.Data.SqlCommonDataProvider, CommunityServer.SqlDataProvider"
29 connectionStringName = "SiteSqlServer" databaseOwnerStringName = "SiteSqlServerOwner"
30 />
31
32 <add
33 name = "ForumDataProvider"
34 type = "CommunityServer.Data.ForumsSqlDataProvider, CommunityServer.SqlDataProvider"
35 connectionStringName = "SiteSqlServer" databaseOwnerStringName = "SiteSqlServerOwner"
36 />
37
38 <add
39 name = "WeblogDataProvider"
40 type = "CommunityServer.Data.WeblogSqlDataProvider, CommunityServer.SqlDataProvider"
41 connectionStringName = "SiteSqlServer" databaseOwnerStringName = "SiteSqlServerOwner"
42 />
43
44 <add
45 name = "GalleryDataProvider"
46 type = "CommunityServer.Data.GallerySqlDataProvider, CommunityServer.SqlDataProvider"
47 connectionStringName = "SiteSqlServer" databaseOwnerStringName = "SiteSqlServerOwner"
48 />
49
50 <add
51 name = "ProviderHelper"
52 type = "CommunityServer.Data.WebSqlProviderHelper, CommunityServer.SqlDataProvider"
53 connectionStringName = "SiteSqlServer" databaseOwnerStringName = "SiteSqlServerOwner"
54 />
55
56 <add
57 name = "SiteUrlsDataProvider"
58 type = "CommunityServer.Components.SiteUrlsData, CommunityServer.Components"
59 path = "SiteUrls.config"
60 />
61
62 <add
63 name = "ApplicationKeyProvider"
64 type = "CommunityServer.Components.ApplicationKeyProvider, CommunityServer.Components"
65 />
66
67 <add
68 name = "EmailTemplateProvider"
69 type = "CommunityServer.Components.XmlEmailTemplateProvider, CommunityServer.Components"
70 />
71
72 <add
73 name = "EmailQueueProvider"
74 type = "CommunityServer.Components.SqlEmailQueueProvider, CommunityServer.Components"
75 connectionStringName = "SiteSqlServer" databaseOwnerStringName = "SiteSqlServerOwner"
76 />
77
78 <add
79 name = "CSMDataProvider"
80 type = "CommunityServer.Mail.Data.CSMSqlDataProvider, CommunityServer.Mail.Data.SqlDataProvider"
81 connectionStringName = "SiteSqlServer" databaseOwnerStringName = "SiteSqlServerOwner"
82 />
83
84 <add
85 name = "SearchProvider"
86 type = "CommunityServer.Components.SearchBarrel.SearchBarrelProvider, CommunityServer.Components.SearchBarrel" />
87
88 <add
89 name = "FileGalleryDataProvider"
90 type = "CommunityServer.Data.FileGallerySqlDataProvider, CommunityServer.SqlDataProvider"
91 connectionStringName = "SiteSqlServer" databaseOwnerStringName = "SiteSqlServerOwner"
92 />
93
94 <add
95 name = "FeedReaderDataProvider"
96 type = "CommunityServer.Data.FeedReaderSqlDataProvider, CommunityServer.SqlDataProvider"
97 connectionStringName = "SiteSqlServer" databaseOwnerStringName = "SiteSqlServerOwner"
98 />
99
100 <add
101 name = "RollerBlogsDataProvider"
102 type = "CommunityServer.RollerBlogs.Data.RollerBlogsSqlDataProvider, CommunityServer.RollerBlogs"
103 connectionStringName = "SiteSqlServer" databaseOwnerStringName = "SiteSqlServerOwner"
104 />
105
106 <add
107 name = "MemberRoleProfileProvider"
108 type = "CommunityServer.MemberRole.CSMemberRoleProfileProvider, CommunityServer.MemberRole"
109 />
110
111
112 </providers>
知道了配置文件，我们可以从CSConfiguration.cs文件中找到Provider的实体类，通过CSConfiguration类将其读取并缓存，这样能提高效率。关于怎样读取，我想回用XML的人都懂得，这里就不多说了，下面来看看代码。
ProviderEntity
1 public class Provider
2 
{
3
string name;
4 ExtensionType extensionType;
5 string providerType;
6 NameValueCollection providerAttributes = new NameValueCollection();
7
8 public Provider (XmlAttributeCollection attributes)
9
{
10
11 // Set the name of the provider
12 //
13 name = attributes["name"].Value;
14
15 if (attributes["extensionType"] != null)
16 {
17 // Set the extension type
18 //
19 try
20 {
21 extensionType = (ExtensionType)Enum.Parse(typeof(ExtensionType), attributes["extensionType"].Value, true);
22
}
23 catch
24 {
25 // Occassionally get an exception on parsing the extensiontype, so set it to Unknown
26 extensionType = ExtensionType.Unknown;
27 }
28 }
29 // Set the type of the provider
30 //
31 providerType = attributes["type"].Value;
32
33 // Store all the attributes in the attributes bucket
34 //
35 foreach (XmlAttribute attribute in attributes)
36 {
37 if ( (attribute.Name != "name") && (attribute.Name != "type") )
38 providerAttributes.Add(attribute.Name, attribute.Value);
39 }
40 }
41
42 public string Name {
43 get {
44 return name;
45 }
46 }
47
48 public ExtensionType ExtensionType
49 {
50 get { return extensionType; }
51 }
52
53 public string Type {
54 get {
55 return providerType;
56 }
57 }
58
59 public NameValueCollection Attributes {
60 get {
61 return providerAttributes;
62 }
63 }
64
65
}
N
me就是上面所说的配置节点中的name属性;Type就是type属性，将其他的如ConnectionString等保存在Attributes中，我们可以通过key&value来读取。到这里我们已经读取了provider配置，但要实现provider还需要通过反射技术，在DataProviders可以看到，这个类主要用于数据库的扩展类，一些非数据库的类大多用SingletonProviderHelper来实现，原理都差不多，主要DataProviders通过查找最匹配的具有(string connectionString,string dataOwrer)来对其实例化，在CSlReWriter类中就可以看到用SingletonProviderHelper来对其虚函数进行实例化。
1public sealed class DataProviders
2 {
3 /**//// <summary>
4 /// This class can not be instantiated
5 /// </summary>
6 private DataProviders()
7 {
8 }
9
10 private static void GetDataStoreParameters(Provider dataProvider, out string connectionString, out string databaseOwner)
11 {
12 databaseOwner = dataProvider.Attributes["databaseOwner"];
13 if(databaseOwner == null || databaseOwner.Trim().Length == 0)
14 databaseOwner = ConfigurationSettings.AppSettings[dataProvider.Attributes["databaseOwnerStringName"]];
15
16 connectionString = dataProvider.Attributes["connectionString"];
17 if(connectionString == null || connectionString.Trim().Length == 0)
18 connectionString = ConfigurationSettings.AppSettings[dataProvider.Attributes["connectionStringName"]];
19 }
20
21 /**//// <summary>
22 /// Creates an instance of the provider using Activator. This instance should be
23 /// cached since it is an expesivie operation
24 /// </summary>
25 public static object CreateInstance(Provider dataProvider)
26 {
27 //Find the current attributes
28 string connectionString = null; //dataProvider.Attributes["connectionString"];
29 string databaseOwner = null;// dataProvider.Attributes["databaseOwner"];
30
31 GetDataStoreParameters(dataProvider, out connectionString, out databaseOwner);
32
33 //Get the type
34 Type type = Type.GetType(dataProvider.Type);
35
36 object newObject = null;
37 if(type != null)
38 {
39 newObject = Activator.CreateInstance(type,new object[]{databaseOwner,connectionString});
40 }
41
42 if(newObject == null) //If we can not create an instance, throw an exception
43 ProviderException(dataProvider.Name);
44
45 return newObject;
46 }
47
48 /**//// <summary>
49 /// Creates and Caches the ConstructorInfo for the specified provider.
50 /// </summary>
51 public static ConstructorInfo CreateConstructorInfo (Provider dataProvider)
52 {
53
54 // The assembly should be in \bin or GAC, so we simply need
55 // to get an instance of the type
56 //
57 CSConfiguration config = CSConfiguration.GetConfig();
58 ConstructorInfo providerCnstr = null;
59 try
60 {
61 //string providerTypeName = ((Provider) config.Providers[providerName]).Type;
62 Type type = Type.GetType( dataProvider.Type );
63
64 // Insert the type into the cache
65 //
66 Type[] paramTypes = new Type[2];
67 paramTypes[0] = typeof(string);
68 paramTypes[1] = typeof(string);
69
70 providerCnstr = type.GetConstructor(paramTypes);
71
72 }
73 catch
74 {
75 ProviderException(dataProvider.Name);
76 }
77
78 if(providerCnstr == null)
79 ProviderException(dataProvider.Name);
80
81 return providerCnstr;
82 }
83
84 /**//// <summary>
85 /// Creates an instance of the specified provider using the Cached
86 /// ConstructorInfo from CreateConstructorInfo
87 /// </summary>
88 public static object Invoke(Provider dataProvider)
89 {
90 object[] paramArray = new object[2];
91
92
93 string dbOwner = null;
94 string connstring = null;
95
96 GetDataStoreParameters(dataProvider, out connstring, out dbOwner);
97
98 paramArray[0] = dbOwner;
99 paramArray[1] = connstring;
100
101 return CreateConstructorInfo(dataProvider).Invoke(paramArray);
102 }
103
104 Exception#region Exception
105 private static void ProviderException(string providerName)
106 {
107 CSConfiguration config = CSConfiguration.GetConfig();
108 HttpContext context = HttpContext.Current;
109 if (context != null)
110 {
111
112 // We can't load the dataprovider
113 //
114 StreamReader reader = new StreamReader( context.Server.MapPath("~/Languages/" + config.DefaultLanguage + "/errors/DataProvider.htm") );
115 string html = reader.ReadToEnd();
116 reader.Close();
117
118 html = html.Replace("[DATAPROVIDERCLASS]", providerName);
119 html = html.Replace("[DATAPROVIDERASSEMBLY]", providerName);
120 context.Response.Write(html);
121 context.Response.End();
122 }
123 else
124 {
125 throw new CSException(CSExceptionType.DataProvider, "Unable to load " + providerName);
126 }
127 }
128 #endregion
通过Type.GetType()来进行类的反射，当然我们需要对其进行实例化才能调用abstract class中的方法和属性，这就要用到Activator.CreateInstance(type,
new object[]{databaseOwner,connectionString}),这个方法对类进行了实例化，当然实例化这个类的构造函数中的参数为(databaseOwner,connectionString);当查找到这个构造函数进行实例化时也将DataProvider中所得到的databaseOwner,connectionString两个变量的值传递给了参数。
OK这样就完成了整个实现过程，如果有不对的地方请批评指正！
posted on 2006-10-15 12:28
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