重写默认ResourceProvider [英] Overriding default ResourceProvider

问题描述

我需要使用的appSettings 定义的应用程序上下文来获取本地资源：

I need to retrieve local resources using an application context defined in appSettings:

<add key="ApplicationContext" value="CTX1"/>

这也可与另一个值部署：

which could also be deployed with another value:

<add key="ApplicationContext" value="CTX2"/>

和这样定义的本地资源：

and define local resources like this:

<root>
  <data name="CTX1_BodyTitle1" xml:space="preserve">
    <value>Welcome to context 1</value>
  </data> 

  <data name="CTX2_BodyTitle1" xml:space="preserve">
    <value>Welcome to context 2</value>
  </data> 
<root>

然后aspx页面使用隐式资源名称：

then use implicit resource name in aspx page:

<h2><asp:Literal runat="server" meta:ressourcekey="BodyTitle1"></asp:Literal></h2>

我想实现一个自定义ResourceProvider在 MSDN 而是告诉没有设法做一些有效的，也不简单。

I tried to implement a custom ResourceProvider as told on msdn but did not manage to do something effective nor simple.

不知道如何privide这一点没有重新实现整个 ResourceProviderFactory ？

Any idea how to privide this without reimplementing the whole ResourceProviderFactory?

编辑：

我要含蓄检索本地从 Page1.en.resx ， Page1.fr.resx 根据ApplicationContext中，然后使用一个唯一的标识符 Page1.aspx的链接到定义的资源。

I want to implicitly retrieve local resources from Page1.en.resx, Page1.fr.resx according to ApplicationContext, then use an unique identifier in Page1.aspx to link to defined resources.

推荐答案

据@BartoszKP的意见，我写了一个自定义的防爆pressionBuilder 是考虑到acount的ApplicationContext和本地化（在比拉勒·海达尔文章基地）：

According to @BartoszKP advice, I wrote a custom ExpressionBuilder that takes into acount ApplicationContext and localization (base on a Bilal Haidar article):

的Web.config有权宣布它：

Web.config has to declare it :

<system.web>
    <expressionBuilders>
        <add expressionPrefix="Contextual" type="SinsedrixLibrary.ContextualExpressionBuilder"/>
    </expressionBuilders>
</system.web>

和aspx页面就必须要求的ressource使用preFIX：

And aspx page just have to request ressource with a prefix:

<h1><asp:Literal runat="server" Text='<%$ Contextual: LitWelcome %>'></asp:Literal></h1>

下面是防爆pressionBuilder ：

namespace SinsedrixLibrary
{
/// <summary>
/// This source file includes the source code for the 
/// XmlSettingExpressionBuilder, which is used to handle
/// declarative expressions based on an XML settings file.
/// </summary>
public class ContextualExpressionBuilder : ExpressionBuilder
{
    public ContextualExpressionBuilder()
    { }
    /// <summary>
    /// This method will be called during page execution
    /// to get the expression that is going to be executed 
    /// to return the value of the declarative expression
    /// </summary>
    /// <param name="entry"></param>
    /// <param name="parsedData"></param>
    /// <param name="context"></param>
    /// <returns></returns>
    public override CodeExpression GetCodeExpression(BoundPropertyEntry entry, object parsedData, ExpressionBuilderContext context)
    {
        // Get a reference to this class since we are going to
        // execute a method on this class that will evaluate
        // the required expression
        CodeTypeReferenceExpression thisType = new CodeTypeReferenceExpression(base.GetType());

        // Create a new expression based on the KEY specified
        // in the declarative expression, this will be used
        // as an input to the method that will evaluate the 
        // required expression
        CodePrimitiveExpression expression = new CodePrimitiveExpression(entry.Expression.Trim().ToString());
        string l_resxPath = Path.GetDirectoryName(context.VirtualPath) + "\\App_LocalResources\\"+ Path.GetFileName(context.VirtualPath);
        CodePrimitiveExpression resxPath = new CodePrimitiveExpression(l_resxPath);

        // The static method name that will evaluate the
        // expression, by accessing the XML file and retreiving
        // the value that corresponds to the key specified
        string evaluationMethod = "GetContextResource";

        // Finally, return the expression that will invoke the method
        // responsible for evaluating the expression
        // The CodeMethodInvokeExpression takes as input the type on which to execute the method specified,
        // the method name, and the array of CodeExpression, which represents the parameters of the method called
        return new CodeMethodInvokeExpression(thisType, evaluationMethod, new CodeExpression[] { expression, resxPath });
    }

    /// <summary>
    /// Evaluates the expression by accessing the XMLSettings file
    /// and retrieve the value corresponding to the key specified in
    /// the input expression.
    /// </summary>
    /// <param name="expression"></param>
    /// <returns></returns>
    public static string GetContextResource(string expression, string resxPath)
    {
        // Get the XML Setting file from the application cache if present
        CultureInfo ci = CultureInfo.CurrentCulture;
        string resxKey = resxPath + "." + ci.TwoLetterISOLanguageName;

        XmlDocument xmlSettingDoc = (XmlDocument)HostingEnvironment.Cache[resxKey];

        // check if there was an already loaded document
        if (xmlSettingDoc == null)
        {
            // Define the document here
            xmlSettingDoc = new XmlDocument();

            // Get the config file path using the HostingEnvironment
            // which gives information for application-specific
            string resxCultureFile = resxKey + ".resx";
            string resxDefaultFile = resxPath + ".resx";
            string resxFile = "";
            try
            {
                resxFile = HostingEnvironment.MapPath(resxCultureFile);
            }
            catch(Exception) {
                resxFile = HostingEnvironment.MapPath(resxDefaultFile);
            }

            // Load the XML file into the XmlDocument
            xmlSettingDoc.Load(resxFile);

            // Create a new file dependency to be used when we add the XmlDocument
            // into the Cache, so that when the XmlSettings file change, the Cache will
            // be invalid.
            CacheDependency settingsDepend = new CacheDependency(resxFile);

            // Add the Xmldocument to the Cache
            HostingEnvironment.Cache.Insert(resxKey, xmlSettingDoc, settingsDepend);
        }

        string ctx = ConfigurationManager.AppSettings["ApplicativeContext"];

        // XPATH key used to retrieve the record needed in the form of add[@key='keyvalue']
        string getXPATHKey = String.Format("//data[@name='{0}_{1}']/value", ctx, expression);

        // Search for that record
        XmlNode wantedRecord = xmlSettingDoc.SelectSingleNode(getXPATHKey);

        // If the record exists, return the value property
        if (wantedRecord != null)
            return wantedRecord.InnerText;

        // return a message informing users that the expression failed to
        // evaluate to a real value
        return string.Format("Unable to Process Expression : '{0}'", expression);
    }
}
}

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