WCF重写ServiceHost，实现独立配置文件

原文地址：/article/4920719.html

有时我们需要将WCF的配置文件放在单独的配置文件中，而默认情况下WCF又是在web.config或app.config中去寻找服务配置。如果我们把配置文件放在另一个config文件中，如何让WCF知道呢？

答案就是重写ServiceHost。在重写中告诉WCF配置文件的路径。

public class MyServiceHost:ServiceHost
{
private string ConfigPath =System.AppDomain.CurrentDomain.BaseDirectory+ "MyApp.config";

public MyServiceHost(Type serviceType, params Uri[] baseAddresses) :
base(serviceType, baseAddresses)
{
}

protected override void ApplyConfiguration()
{
// Check user config invalidation
if (!CheckConfigExist(ConfigPath))
{
// Use default config
base.ApplyConfiguration();
return;
}
//base.ApplyConfiguration();
// Use user config
ExeConfigurationFileMap execfgMap = new ExeConfigurationFileMap();
// Set user config FilePath
execfgMap.ExeConfigFilename = ConfigPath;
// Config info
Configuration cfg = ConfigurationManager.OpenMappedExeConfiguration(execfgMap,ConfigurationUserLevel.None);
// Gets all service model config sections
ServiceModelSectionGroup servicemodelSections = ServiceModelSectionGroup.GetSectionGroup(cfg);

// Find serivce section matched with the name "this.Description.ServiceType.FullName"
if (!ApplySectionInfo(this.Description.ServiceType.FullName,servicemodelSections))
{
throw new Exception("ConfigApply Error : There is no endpoint existed in your config!! Please check your config file!");
}
this.ApplyMultiBehaviors(servicemodelSections);

}

/// <summary>
/// Check config file!
/// </summary>
/// <param name="configpath"></param>
/// <returns></returns>
private bool CheckConfigExist(string configpath)
{
if (string.IsNullOrEmpty(configpath)) return false;
if (!File.Exists(configpath)) return false;
return true;
}

/// <summary>
/// Apply section info
/// </summary>
/// <param name="serviceFullName"></param>
/// <param name="servicemodelSections"></param>
/// <returns></returns>
private bool ApplySectionInfo(string serviceFullName, ServiceModelSectionGroup servicemodelSections)
{
// Check config sections (!including one section at least!)
if (servicemodelSections == null) return false;
// Service name can't be none!
if (string.IsNullOrEmpty(serviceFullName)) return false;
bool isElementExist = false;
foreach (ServiceElement element in servicemodelSections.Services.Services)
{
if (element.Name == serviceFullName)
{
// Find successfully & apply section info of config file
base.LoadConfigurationSection(element);
// Find service element successfully
isElementExist = true;
break;
}
}
return isElementExist;
}

/// <summary>
/// Add behaviors
/// </summary>
/// <param name="servicemodelSections"></param>
/// <returns></returns>
private bool ApplyMultiBehaviors(ServiceModelSectionGroup servicemodelSections)
{
if (servicemodelSections == null) return false;
foreach (ServiceBehaviorElement element in servicemodelSections.Behaviors.ServiceBehaviors)
{
foreach (BehaviorExtensionElement behavior in element)
{
BehaviorExtensionElement behaviorEx = behavior;
object extention = behaviorEx.GetType().InvokeMember("CreateBehavior",
BindingFlags.InvokeMethod | BindingFlags.NonPublic | BindingFlags.Instance,
null,
behaviorEx,
null);
if (extention == null) continue;
IServiceBehavior isb = (IServiceBehavior)extention;
//if (base.Description.Behaviors.Contains(isb)) break;
bool isbehaviorExisted = false;
foreach (IServiceBehavior i in base.Description.Behaviors)
{
if (i.GetType().Name == isb.GetType().Name)
{
isbehaviorExisted = true;
break;
}
}
if (isbehaviorExisted) break;
base.Description.Behaviors.Add((IServiceBehavior)extention);
}
}
return true;
}

}

像上面那样，我们就把配置文件移到了MyApp.config。如果是控制台程序类的WCF服务就可以像下面那样来启动：

using (MyServiceHost host=new MyServiceHost(typeof(Service1)))
{
//... do something
host.Open();
}

而对于宿主是IIS的WCF服务，我们还需要再重写ServiceHostFactory：

public class MyServiceHostFactory :  ServiceHostFactory
{
protected override ServiceHost CreateServiceHost(Type serviceType, Uri[] baseAddresses)
{
return new MyServiceHost(serviceType, baseAddresses);
}
}

然后在WCF服务的svc文件中，指定factory属性的值为我们重写的ServiceHostFactory：

<%@ ServiceHost Factory="WcfService1.MyServiceHostFactory"  Language="C#" Debug="true" Service="WcfService1.Service1" CodeBehind="Service1.svc.cs" %>