一.响应配置变更通知:
Configuration Application Block提供了一个事件机制,当存储的配置变更时通知应用程序 ,使用步骤:
1)创建一个EverntHandler
2 /// 创建EventHanler
3 /// </summary>
4 /// <param name="sender"></param>
5 /// <param name="args"></param>
6 private void OnConfigurationChanged( object sender, ConfigurationChangedEventArgs args)
7 {
8 Cursor = System.Windows.Forms.Cursors.WaitCursor;
9
10 EditorFontData configData = ConfigurationManager.GetConfiguration("EditorSettings") as EditorFontData;
11
12 StringBuilder results = new StringBuilder();
13 results.Append("Configuration changes in storage were detected. Updating configuration.");
14 results.Append(Environment.NewLine);
15 results.Append("New configuration settings:");
16 results.Append(Environment.NewLine);
17 results.Append('\t');
18 results.Append(configData.ToString());
19 results.Append(Environment.NewLine);
20
21 Cursor = System.Windows.Forms.Cursors.Arrow;
22 }
2)注册事件
2 ConfigurationManager.ConfigurationChanged += new ConfigurationChangedEventHandler(OnConfigurationChanged);
二.配置数据的缓存:
Configuration Application Block在设计时提供了对配置数据的缓存,在读取XML数据后,再次读取它首先会判断缓存是否为空,如果不为空,它会直接从缓存中读取数据(在剖析篇中会有详细的介绍)。
显式的清除掉缓存用下面这句代码即可:
2 ConfigurationManager.ClearSingletonSectionCache();
三.面向高级人员的扩展机制:
1. 除了用XML文件可以存储数据外,还可以创建自己的存储方式,像SQL Server Database,注册表存储等,这时就需要我们自己创建StorageProvider。创建自定义的Storage Provider,需要注意以下几点:
1)要读取和写入数据,需要继承于StorageProvider类和分别实现IStorageProviderReader和IstorageProviderWriter接口:
2 {
3 //……
4 }
2)如果实现了IConfigurationProvider接口,则方法Initialize()就不能为空,也必须实现:
2 {
3 //……
4 }
3)实现Read()和Write()方法,记住一定要返回类型为object,否则Transformer将无法使用:
2 {
3 //……
4 }
5
6 public void Write( object value)
7 {
8 //……
9 }
2.创建自定义的Transformer
如果我们创建的自定义的Storage Provider不能后支持XMLNode,这时候我们需要创建自己的Transformer,需要注意以下几点:
1)自定义的Transformer如果实现了Itransformer接口;则必须实现方法Serialize()和Deserialize();
2)自定义的Transformer如果实现了IConfigurationProvider接口,则方法Initialize()就不能为空,也必须实现;
下面给出一个SoapSerializerTransformer的例子程序(先声名一下,这个例子程序不是我写的,而是Dario Fruk先生^_^):
2 {
3 using System;
4 using System.Configuration;
5 using System.IO;
6 using System.Runtime.Serialization.Formatters.Soap;
7 using System.Text;
8 using System.Xml;
9
10 using Microsoft.Practices.EnterpriseLibrary.Common;
11 using Microsoft.Practices.EnterpriseLibrary.Configuration;
12
13 /**//// <summary>
14 /// SoapSerializerTransformer is a custom Serialization Transformer for Microsft Enterprise Library 1.0.
15 /// </summary>
16 public class SoapSerializerTransformer : TransformerProvider
17 {
18 public override void Initialize(ConfigurationView configurationView)
19 {
20 // Do nothing. This implementation does not require any additional configuration data because SoapFormatter reflects types
21 // during serialization.
22 }
23
24 public override object Serialize(object value)
25 {
26 SoapFormatter soapFormatter = new SoapFormatter();
27 StringBuilder stringBuilder = new StringBuilder();
28 XmlDocument doc = new XmlDocument();
29
30 stringBuilder.Append("<soapSerializerSection>");
31
32 string serializedObject = "";
33 using (MemoryStream stream = new MemoryStream())
34 {
35 soapFormatter.Serialize(stream, value);
36 byte[] buffer = stream.GetBuffer();
37 // quick fix for 0-byte padding
38 serializedObject = ASCIIEncoding.ASCII.GetString(buffer).Replace('\0', ' ').Trim();
39 }
40 stringBuilder.Append(serializedObject);
41
42 stringBuilder.Append("</soapSerializerSection>");
43 doc.LoadXml(stringBuilder.ToString());
44
45 return doc.DocumentElement;
46 }
47
48 public override object Deserialize(object section)
49 {
50 ArgumentValidation.CheckForNullReference(section, "section");
51 ArgumentValidation.CheckExpectedType(section, typeof(XmlNode));
52
53 XmlNode sectionNode = (XmlNode)section;
54
55 XmlNode serializedObjectNode = sectionNode.SelectSingleNode("//soapSerializerSection");
56 if (serializedObjectNode == null)
57 {
58 throw new ConfigurationException("The required element '<soapSerializationSection>' missing in the specified Xml configuration file.");
59 }
60
61 SoapFormatter soapFormatter = new SoapFormatter();
62 try
63 {
64 object obj = null;
65 using (MemoryStream stream = new MemoryStream())
66 {
67 using (StreamWriter sw = new StreamWriter(stream, Encoding.ASCII))
68 {
69 sw.Write(serializedObjectNode.InnerXml);
70 sw.Flush();
71 // rewind stream to the begining or deserialization will throw Exception.
72 sw.BaseStream.Seek(0, SeekOrigin.Begin);
73 obj = soapFormatter.Deserialize(stream);
74 }
75 }
76 return obj;
77 }
78 catch (InvalidOperationException e)
79 {
80 string message = e.Message;
81 if (null != e.InnerException)
82 {
83 message = String.Concat(message, " ", e.InnerException.Message);
84 }
85 throw new ConfigurationException(message, e);
86 }
87 }
88 }
89}
3.使用其它的Providers
SQL Server Provider:使用数据库SQL Server Provider
Registry Provider:使用注册表Provider
四.保护配置信息:
配置信息直接放在了XML文件里面是不安全,我们可以用加密应用程序块对其进行加密,其实对于所有的应用程序块的配置信息都可以进行加密,我们到加密应用程序块时再详细讨论:)
进阶篇就写到这里了,后面继续剖析篇,在剖析篇里我会从配置应用程序块的底层设计,到类设计等作一些介绍(个人理解^_^)