如何：在服务协定中声明错误

项目
04/07/2023

在托管代码中，出现错误条件时引发异常。但是，在 Windows Communication Foundation (WCF) 应用程序中，通过在服务协定中声明 SOAP 错误可以使服务协定指定向客户端返回哪些错误信息。有关异常和错误之间的关系的概述，请参阅在协定和服务中指定和处理错误。

创建指定 SOAP 错误的服务协定

创建至少包含一个操作的服务协定。有关示例，请参阅如何：定义服务协定。
选择可以指定希望向客户端通知的错误条件的操作。若要确定将 SOAP 错误返回到客户端的合理错误条件，请参阅在协定和服务中指定和处理错误。

为所选操作应用 System.ServiceModel.FaultContractAttribute 并向构造函数传递可序列化错误类型。有关创建和使用可序列化类型的详细信息，请参阅在服务协定中指定数据传输。下面的示例演示如何指定 SampleMethod 操作可以产生 GreetingFault。

[OperationContract]
[FaultContractAttribute(
  typeof(GreetingFault),
  Action="http://www.contoso.com/GreetingFault",
  ProtectionLevel=ProtectionLevel.EncryptAndSign
  )]
string SampleMethod(string msg);

<OperationContract, FaultContractAttribute(GetType(GreetingFault), Action:="http://www.contoso.com/GreetingFault", ProtectionLevel:=ProtectionLevel.EncryptAndSign)> _
Function SampleMethod(ByVal msg As String) As String

为向客户端传达错误条件的协定中的所有操作重复步骤 2 和步骤 3。

实现返回指定 SOAP 错误的操作

操作指定可以返回特定 SOAP 错误（例如在前面的过程中）来向调用应用程序传达错误条件后，下一步就是实现该指定。

在操作中引发指定的 SOAP 错误

当操作中出现 FaultContractAttribute 指定的错误条件时，将引发一个新的 System.ServiceModel.FaultException<TDetail>，其中指定的 SOAP 错误是类型参数。下面的示例演示如何在前面的过程和以下代码部分中显示的 GreetingFault 中引发 SampleMethod。
```
throw new FaultException<GreetingFault>(new GreetingFault("A Greeting error occurred. You said: " + msg));
```
```
    Throw New FaultException(Of GreetingFault)(New GreetingFault("A Greeting error occurred. You said: " & msg))
End If
```

示例

下面的代码示例演示为 GreetingFault 操作指定 SampleMethod 的单个操作的实现。

using System;
using System.Collections.Generic;
using System.Net.Security;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.Text;

namespace Microsoft.WCF.Documentation
{
  [ServiceContract(Namespace="http://microsoft.wcf.documentation")]
  public interface ISampleService{
    [OperationContract]
    [FaultContractAttribute(
      typeof(GreetingFault),
      Action="http://www.contoso.com/GreetingFault",
      ProtectionLevel=ProtectionLevel.EncryptAndSign
      )]
    string SampleMethod(string msg);
  }

  [DataContractAttribute]
  public class GreetingFault
  {
    private string report;

    public GreetingFault(string message)
    {
      this.report = message;
    }

    [DataMemberAttribute]
    public string Message
    {
      get { return this.report; }
      set { this.report = value; }
    }
  }

  class SampleService : ISampleService
  {
  #region ISampleService Members

  public string  SampleMethod(string msg)
  {
    Console.WriteLine("Client said: " + msg);
    // Generate intermittent error behavior.
    Random rnd = new Random(DateTime.Now.Millisecond);
    int test = rnd.Next(5);
    if (test % 2 != 0)
      return "The service greets you: " + msg;
    else
      throw new FaultException<GreetingFault>(new GreetingFault("A Greeting error occurred. You said: " + msg));
  }

  #endregion
  }
}


Imports System.Collections.Generic
Imports System.Net.Security
Imports System.Runtime.Serialization
Imports System.ServiceModel
Imports System.Text

Namespace Microsoft.WCF.Documentation
    <ServiceContract(Namespace:="http://microsoft.wcf.documentation")> _
    Public Interface ISampleService
        <OperationContract, FaultContractAttribute(GetType(GreetingFault), Action:="http://www.contoso.com/GreetingFault", ProtectionLevel:=ProtectionLevel.EncryptAndSign)> _
        Function SampleMethod(ByVal msg As String) As String
    End Interface

    <DataContractAttribute> _
    Public Class GreetingFault
        Private report As String

        Public Sub New(ByVal message As String)
            Me.report = message
        End Sub

        <DataMemberAttribute> _
        Public Property Message() As String
            Get
                Return Me.report
            End Get
            Set(ByVal value As String)
                Me.report = value
            End Set
        End Property
    End Class

    Friend Class SampleService
        Implements ISampleService
#Region "ISampleService Members"

        Public Function SampleMethod(ByVal msg As String) As String Implements ISampleService.SampleMethod
            Console.WriteLine("Client said: " & msg)
            ' Generate intermittent error behavior.
            Dim rand As New Random(DateTime.Now.Millisecond)
            Dim test As Integer = rand.Next(5)
            If test Mod 2 <> 0 Then
                Return "The service greets you: " & msg
            Else
                Throw New FaultException(Of GreetingFault)(New GreetingFault("A Greeting error occurred. You said: " & msg))
            End If
        End Function

#End Region
    End Class
End Namespace

通过

如何：在服务协定中声明错误

创建指定 SOAP 错误的服务协定

实现返回指定 SOAP 错误的操作

在操作中引发指定的 SOAP 错误

示例

另请参阅

其他资源