Enumerates the resources in a binary resources (.resources) file by reading sequential resource name/value pairs.
Assembly: mscorlib (in mscorlib.dll)
Thetype exposes the following members.
|Close||Releases all operating system resources associated with this object.|
|Dispose||Releases all resources used by the current instance of the class.|
|Equals(Object)||Determines whether the specified object is equal to the current object. (Inherited from Object.)|
|GetEnumerator||Returns an enumerator for this object.|
|GetHashCode||Serves as the default hash function. (Inherited from Object.)|
|GetResourceData||Retrieves the type name and data of a named resource from an open resource file or stream.|
|GetType||Gets the Type of the current instance. (Inherited from Object.)|
|ToString||Returns a string that represents the current object. (Inherited from Object.)|
|AsParallel||Enables parallelization of a query. (Defined by ParallelEnumerable.)|
|AsQueryable||Converts an IEnumerable to an IQueryable. (Defined by Queryable.)|
|Cast(TResult)||Casts the elements of an IEnumerable to the specified type. (Defined by Enumerable.)|
|OfType(TResult)||Filters the elements of an IEnumerable based on a specified type. (Defined by Enumerable.)|
The class provides a standard implementation of the IResourceReader interface. A instance represents either a standalone .resources file or a .resources file that is embedded in an assembly. It is used to enumerate the resources in a .resources file and retrieve its name/value pairs. It differs from the ResourceManager class, which is used to retrieve specified named resources from a .resources file that is embedded in an assembly. The ResourceManager class is used to retrieve resources whose names are known in advance, whereas the class is useful for retrieving resources whose number or precise names are not known at compile time. For example, an application may use a resources file to store configuration information that is organized into sections and items in a section, where the number of sections or items in a section is not known in advance. Resources can then be named generically (such as Section1, Section1Item1, Section1Item2, and so on) and retrieved by using a object.
This type implements the IDisposable interface. When you have finished using the type, you should dispose of it either directly or indirectly. To dispose of the type directly, call its Dispose method in a try/catch block. To dispose of it indirectly, use a language construct such as using (in C#) or Using (in Visual Basic). For more information, see the “Using an Object that Implements IDisposable” section in the IDisposable interface topic.
For more information about using the class, see the following sections:
Instantiating a ResourceReader Object
A .resources file is a binary file that has been compiled from either a text file or an XML .resx file by Resgen.exe (Resource File Generator). A object can represent either a standalone .resources file or a .resources file that has been embedded in an assembly.
To instantiate a object that reads from a standalone .resources file, use the class constructor with either an input stream or a string that contains the .resources file name. The following example illustrates both approaches. The first instantiates a object that represents a .resources file named Resources1.resources by using its file name. The second instantiates a object that represents a .resources file named Resources2.resources by using a stream created from the file.
To create a object that represents an embedded .resources file, instantiate an Assembly object from the assembly in which the .resources file is embedded. Its Assembly.GetManifestResourceStream method returns a Stream object that can be passed to the ResourceReader(Stream) constructor. The following example instantiates a object that represents an embedded .resources file.
Enumerating a ResourceReader Object's Resources
To enumerate the resources in a .resources file, you call the GetEnumerator method, which returns an System.Collections.IDictionaryEnumerator object. You call the IDictionaryEnumerator.MoveNext method to move from one resource to the next. The method returns false when all the resources in the .resources file have been enumerated.
Although the class implements the IEnumerable interface and the IEnumerable.GetEnumerator method, the ResourceReader.GetEnumerator method does not provide the IEnumerable.GetEnumerator implementation. Instead, the ResourceReader.GetEnumerator method returns an IDictionaryEnumerator interface object that provides access to each resource's name/value pair.
You can retrieve the individual resources in the collection in two ways:
You can iterate each resource in the System.Collections.IDictionaryEnumerator collection and use System.Collections.IDictionaryEnumerator properties to retrieve the resource name and value. We recommend this technique when all the resources are of the same type, or you know the data type of each resource.
You can retrieve the name of each resource when you iterate the System.Collections.IDictionaryEnumerator collection and call the GetResourceData method to retrieve the resource's data. We recommend this approach when you do not know the data type of each resource or if the previous approach throws exceptions.
The first method of enumerating the resources in a .resources file involves directly retrieving each resource's name/value pair. After you call the IDictionaryEnumerator.MoveNext method to move to each resource in the collection, you can retrieve the resource name from the IDictionaryEnumerator.Key property and the resource data from the IDictionaryEnumerator.Value property.
The following example shows how to retrieve the name and value of each resource in a .resources file by using the IDictionaryEnumerator.Key and IDictionaryEnumerator.Value properties. To run the example, create the following text file named ApplicationResources.txt to define string resources.
Title="Contact Information" Label1="First Name:" Label2="Middle Name:" Label3="Last Name:" Label4="SSN:" Label5="Street Address:" Label6="City:" Label7="State:" Label8="Zip Code:" Label9="Home Phone:" Label10="Business Phone:" Label11="Mobile Phone:" Label12="Other Phone:" Label13="Fax:" Label14="Email Address:" Label15="Alternate Email Address:"
You can then convert the text resource file to a binary file named ApplicationResources.resources by using the following command:
The following example then uses the class to enumerate each resource in the standalone binary .resources file and to display its key name and corresponding value.
The attempt to retrieve resource data from the IDictionaryEnumerator.Value property can throw the following exceptions:
A FormatException if the data is not in the expected format.
A FileNotFoundException if the assembly that contains the type to which the data belongs cannot be found.
A TypeLoadException if the type to which the data belongs cannot be cannot be found.
Typically, these exceptions are thrown if the .resources file has been modified manually, if the assembly in which a type is defined has either not been included with an application or has been inadvertently deleted, or if the assembly is an older version that predates a type. If one of these exceptions is thrown, you can retrieve resources by enumerating each resource and calling the GetResourceData method, as the following section shows. This approach provides you with some information about the data type that the IDictionaryEnumerator.Value property attempted to return.
The second approach to enumerating resources in a .resources file also involves navigating through the resources in the file by calling the IDictionaryEnumerator.MoveNext method. For each resource, you retrieve the resource's name from the IDictionaryEnumerator.Key property, which is then passed to the GetResourceData(String, String, Byte) method to retrieve the resource's data. This is returned as a byte array in the resourceData argument.
This approach is more awkward than retrieving the resource name and value from the IDictionaryEnumerator.Key and IDictionaryEnumerator.Value properties, because it returns the actual bytes that form the resource value. However, if the attempt to retrieve the resource throws an exception, the GetResourceData method can help identify the source of the exception by supplying information about the resource's data type. For more information about the string that indicates the resource's data type, see GetResourceData.
The following example illustrates how to use this approach to retrieve resources and to handle any exceptions that are thrown. It programmatically creates a binary .resources file that contains four strings, one Boolean, one integer, one bitmap, and one custom DateTimeTZI object. To run the example, do the following:
Create an assembly named Library.dll that contains the DateTimeTZI structure. The following is the source code for the assembly.
Compile the source code in C# by using the following command:
csc /t:library library.cs
Or, you can compile it in Visual Basic by using the following command:
vbc library.vb /t:library
Compile and execute the following source code, which creates a .resources file named ContactResources.resources.
The source code file is named CreateResources.cs. You can compile it in C# by using the following command:
csc CreateResources.cs /r:library.dll
Or, you can compile it in Visual Basic by using the following command:
vbc CreateResources.vb /r:library.dll
Compile and run the following code to enumerate the resources in the ContactResources.resources file.
After modifying the source code (for example, by deliberately throwing a FormatException at the end of the try block) or renaming the Library.dll assembly so that it is unavailable at runtime, you can run the example to see how calls to GetResourceData enable you to retrieve or recreate some resource information.
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