How do I validate an XML document against a DTD in C#?

前端 未结 4 1779
长发绾君心
长发绾君心 2021-01-05 07:21

I don\'t want to do anything fancy, I just want to make sure a document is valid, and print an error message if it is not. Google pointed me to this, but it seems XmlValidat

4条回答
  •  梦毁少年i
    2021-01-05 08:08

    full description:

    1. In Visual Studio .NET, create a new Visual C# Console Application project named ValidateXml. Add two using statements to the beginning of Class1.cs as follows:

      using System.Xml;        // for XmlTextReader and XmlValidatingReader
      using System.Xml.Schema; // for XmlSchemaCollection (which is used later)
      
    2. In Class1.cs, declare a boolean variable named isValid before the start of the Main method as follows:

      private static bool isValid = true;      // If a validation error occurs,
                                               // set this flag to false in the
                                               // validation event handler. 
      
    3. Create an XmlTextReader object to read an XML document from a text file in the Main method, and then create an XmlValidatingReader to validate this XML data as follows:

      XmlTextReader r = new XmlTextReader("C:\\MyFolder\\ProductWithDTD.xml");
      XmlValidatingReader v = new XmlValidatingReader(r);
      
    4. The ValidationType property of the XmlValidatingReader object indicates the type of validation that is required (DTD, XDR, or Schema). Set this property to DTD as follows:

      v.ValidationType = ValidationType.DTD;
      
    5. If any validation errors occur, the validating reader generates a validation event. Add the following code to register a validation event handler (you will implement the MyValidationEventHandler method in Step 7):

      v.ValidationEventHandler += 
         new ValidationEventHandler(MyValidationEventHandler);
      
    6. Add the following code to read and validate the XML document. If any validation errors occur, MyValidationEventHandler is called to address the error. This method sets isValid to false (see Step 8). You can check the status of isValid after validation to see if the document is valid or invalid.

      while (v.Read())
      {
         // Can add code here to process the content.
      }
      v.Close();
      
      // Check whether the document is valid or invalid.
      if (isValid)
         Console.WriteLine("Document is valid");
      else
         Console.WriteLine("Document is invalid");
      
    7. Write the MyValidationEventHandler method after the Main method as follows:

      public static void MyValidationEventHandler(object sender, 
                                                  ValidationEventArgs args) 
      {
         isValid = false;
         Console.WriteLine("Validation event\n" + args.Message);
      }
      

    Build and run the application. The application should report that the XML document is valid. e.g.: In Visual Studio .NET, modify ProductWithDTD.xml to invalidate it (for example, delete the M soliman element). Run the application again. You should receive the following error message:

    Validation event
    Element 'Product' has invalid content. Expected 'ProductName'.
    An error occurred at file:///C:/MyFolder/ProductWithDTD.xml(4, 5).
    Document is invalid
    

提交回复
热议问题