解析Silverlight调用WCF/Rest异常的解决方法

解析Silverlight调用WCF/Rest异常的解决方法。下面我们来一步步讲解。

问题描述

在使用Silverlight调用WCF/Rest服务时，可能会遇到各种异常错误，比如：

• System.ServiceModel.CommunicationException
• System.ServiceModel.FaultException
• System.Net.WebException等等。

那么，如何解决这些异常呢？接下来，将详细讲解这个问题。

解决方法

针对这个问题，我们可以有以下方式解决：

1. 在服务端增加配置

在服务端的web.config中添加以下配置：

<system.serviceModel>
  <services>
    <service name="MyService">
      <endpoint binding="customBinding" bindingConfiguration="crossDomain" contract="IMyService" />
      <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />
      <host>
        <baseAddresses>
          <add baseAddress="http://localhost:8000/MyService/" />
        </baseAddresses>
      </host>
    </service>
  </services>
  <bindings>
    <customBinding>
      <binding name="crossDomain">
        <textMessageEncoding messageVersion="Soap11" />
        <httpTransport allowCookies="false" authenticationScheme="Anonymous" bypassProxyOnLocal="true" hostNameComparisonMode="WeakWildcard" maxBufferSize="65536" maxBufferPoolSize="524288" maxReceivedMessageSize="65536" useDefaultWebProxy="true"/>
      </binding>
    </customBinding>
  </bindings>
  <behaviors>
    <serviceBehaviors>
      <behavior>
        <serviceMetadata httpGetEnabled="false" />
        <serviceDebug includeExceptionDetailInFaults="true" />
      </behavior>
    </serviceBehaviors>
  </behaviors>
  <serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true" />
</system.serviceModel>

2. 在客户端增加配置

在客户端的App.config中添加以下配置：

<system.serviceModel>
  <bindings>
    <customBinding>
      <binding name="CustomBinding_IMyService">
        <textMessageEncoding messageVersion="Soap11" />
        <httpTransport maxReceivedMessageSize="2147483647" allowCookies="true" authenticationScheme="Anonymous" bypassProxyOnLocal="false" hostNameComparisonMode="StrongWildcard" proxyAuthenticationScheme="Anonymous" realm="" useDefaultWebProxy="false" />
      </binding>
    </customBinding>
  </bindings>
  <client>
    <endpoint address="http://localhost:8000/MyService/" binding="customBinding" bindingConfiguration="CustomBinding_IMyService" contract="IMyService" name="CustomBinding_IMyService" />
  </client>
</system.serviceModel>

示例一：使用Rest服务获取数据

在服务端，我们可以创建TestService.svc文件，内容如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.ServiceModel.Web;
using System.Text;

namespace TestService
{
    [ServiceContract]
    public interface ITestService
    {
        [OperationContract]
        [WebGet(UriTemplate = "/GetData/{value}", ResponseFormat = WebMessageFormat.Json)]
        string GetData(string value);
    }

    public class TestService : ITestService
    {
        public string GetData(string value)
        {
            return "You entered: " + value;
        }
    }
}

在客户端，我们可以使用以下代码调用服务：

private void CallRestService()
{
    WebClient client = new WebClient();
    client.DownloadStringCompleted += new DownloadStringCompletedEventHandler(OnDownloadStringCompleted);
    client.DownloadStringAsync(new Uri("http://localhost:8000/TestService/GetData/123"));
}

private void OnDownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
{
    if (e.Error == null)
    {
        MessageBox.Show(e.Result);
    }
    else
    {
        MessageBox.Show(e.Error.Message);
    }
}

示例二：使用WCF服务获取数据

在服务端，我们可以创建TestService.svc文件，内容如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.ServiceModel.Web;
using System.Text;

namespace TestService
{
    [ServiceContract]
    public interface ITestService
    {
        [OperationContract]
        string GetData(string value);
    }

    public class TestService : ITestService
    {
        public string GetData(string value)
        {
            return "You entered: " + value;
        }
    }
}

在客户端，我们可以使用以下代码调用服务：

private void CallWcfService()
{
    TestServiceClient client = new TestServiceClient();
    client.GetDataCompleted += new EventHandler<GetDataCompletedEventArgs>(OnGetDataCompleted);
    client.GetDataAsync("123");
}

private void OnGetDataCompleted(object sender, GetDataCompletedEventArgs e)
{
    if (e.Error == null)
    {
        MessageBox.Show(e.Result);
    }
    else
    {
        MessageBox.Show(e.Error.Message);
    }
}

通过以上方式，我们就可以解决Silverlight调用WCF/Rest异常的问题了。