.NET的动态编译与WS服务调用

动态编译与WS服务，有关系么？今天就乱弹一番，如何使用动态编译动态生成WS服务调用的代理类，然后通过这个代理类调用WS服务。

首先，动态编译这玩意在.NET里面是非常简单的，实际上只涉及到两个类型：CodeDomProvider以及CompilerParameters他们都位于System.CodeDom.Compiler命名空间。

以下代码可将源码动态编译为一个程序集：

动态编译

CodeDomProvider provider = CodeDomProvider.CreateProvider("CSharp");

CompilerParameters codeParameters = new CompilerParameters();

codeParameters.GenerateExecutable = false; //编译为dll，如果为true则编译为exe

codeParameters.GenerateInMemory = true; //编译后的程序集保存到内存中

StringBuilder code = new StringBuilder();

```
//此处构造源代码
```

CompilerResults results = provider.CompileAssemblyFromSource(codeParameters, code.ToString());

Assembly assembly = null; //动态编译生成的程序集

```
if (!results.Errors.HasErrors)
```
```
{
```

    assembly = results.CompiledAssembly;

```
}
```

获得assembly后，随后我们即可以通过反射获取程序集里面的类型，然后实例化，调用类型方法…

不过在此之前，我们得构造WS服务的代理类，它是什么样子的呢？我们使用WCF框架，创建服务代理类也是十分简单的，常见的代理类结构如下：

服务调用代理类

[ServiceContract(Namespace="http://tempuri.org/")]

```
public interface TestService
```
```
{
```

    [OperationContract(Action = "http://tempuri.org/HelloWorld", ReplyAction = "http://tempuri.org/HelloWorldResponse")]

```
    string HelloWorld();
```
```
}
```

public class TestServiceClient : ClientBase<TestService>, TestService

```
{
```

    public TestServiceClient(Binding binding, EndpointAddress address) :

```
        base(binding, address)
```
```
    {
```
```
    }
```
```
    public string HelloWorld()
```
```
    {
```

        return base.Channel.HelloWorld();

```
    }
```
```
}
```

所以，我们要动态构造出代理类源码，应该知道服务的命名空间、服务方法的Action地址、ReplyAction地址，当然还有服务方法的名称，返回类型，参数列表。这里，我们省略掉服务方法的参数列表，构造代理类，实际上就是一个字符串组装的问题，先创建一个类型，用于保存构造代理类所要用到的参数：

服务代理类构造参数

```
public class WebServiceParamaters
```
```
{
```
```
    public string address;
```
```
    public string Address
```
```
    {
```
```
        get { return address; }
```
```
        set
```
```
        {
```
```
            address = value;
```
```
        }
```
```
    }
```
```
    private string serviceNamespace;
```
```
    public string ServiceNamespace
```
```
    {
```

        get { return serviceNamespace; }

```
        set
```
```
        {
```
```
            serviceNamespace = value;
```
```
        }
```
```
    }
```
```
    private string methodAction;
```
```
    public string MethodAction
```
```
    {
```
```
        get { return methodAction; }
```
```
        set
```
```
        {
```
```
            methodAction = value;
```
```
        }
```
```
    }
```
```
    private string methodReplyAction;
```
```
    public string MethodReplyAction
```
```
    {
```

        get { return methodReplyAction; }

```
        set
```
```
        {
```
```
            methodReplyAction = value;
```
```
        }
```
```
    }
```
```
    private string methodName;
```
```
    public string MethodName
```
```
    {
```
```
        get { return methodName; }
```
```
        set
```
```
        {
```
```
            methodName = value;
```
```
        }
```
```
    }
```
```
    private string returnType;
```
```
    public string ReturnType
```
```
    {
```
```
        get { return returnType; }
```
```
        set
```
```
        {
```
```
            returnType = value;
```
```
        }
```
```
    }
```
```
}
```

好，现在我们只需要构造出代理类源码，然后动态编译出代理类的程序集，最后通过反射调用服务方法：

WebServiceProxyCreator

```
public class WebServiceProxyCreator
```
```
{
```

    public Object WebServiceCaller(WebServiceParamaters parameters)

```
    {
```

        CodeDomProvider provider = CodeDomProvider.CreateProvider("CSharp");

        CompilerParameters codeParameters = new CompilerParameters();

        codeParameters.GenerateExecutable = false;

        codeParameters.GenerateInMemory = true;

        StringBuilder code = new StringBuilder();

        CreateProxyCode(code, parameters);

codeParameters.ReferencedAssemblies.Add("System.dll");
codeParameters.ReferencedAssemblies.Add("System.ServiceModel.dll");

        CompilerResults results = provider.CompileAssemblyFromSource(codeParameters, code.ToString());

```
        Assembly assembly = null; 
```
```
        if (!results.Errors.HasErrors)
```
```
        {
```

            assembly = results.CompiledAssembly;

```
        }
```

        Type clientType = assembly.GetType("RuntimeServiceClient");

        ConstructorInfo ci = clientType.GetConstructor(new Type[] { typeof(Binding), typeof(EndpointAddress) });

        BasicHttpBinding binding = new BasicHttpBinding(); //只演示传统的WebService调用

        EndpointAddress address = new EndpointAddress(parameters.address);

        Object client = ci.Invoke(new object[] { binding, address });

        MethodInfo mi = clientType.GetMethod(parameters.MethodName);

        Object result = mi.Invoke(client, null);

        mi = clientType.GetMethod("Close"); //关闭代理

```
        mi.Invoke(client, null);
```
```
        return result;
```
```
    }
```

    public static void CreateProxyCode(StringBuilder code, WebServiceParamaters parameters)

```
    {
```

        code.AppendLine("using System;");

        code.AppendLine("using System.ServiceModel;");

        code.AppendLine("using System.ServiceModel.Channels;");

        code.Append(@"[ServiceContract(");

        if (!String.IsNullOrEmpty(parameters.ServiceNamespace))

```
        {
```

            code.Append("Namespace=\"").Append(parameters.ServiceNamespace).Append("\"");

```
        }
```
```
        code.AppendLine(")]");
```

        code.AppendLine("public interface IRuntimeService");

```
        code.AppendLine("{");
```

        code.Append("[OperationContract(");

        if (!String.IsNullOrEmpty(parameters.MethodAction))

```
        {
```

            code.Append("Action=\"").Append(parameters.MethodAction).Append("\"");

            if (!String.IsNullOrEmpty(parameters.MethodReplyAction))

```
            {
```
```
                code.Append(", ");
```
```
            }
```
```
        }
```

        if (!String.IsNullOrEmpty(parameters.MethodReplyAction))

```
        {
```

            code.Append("ReplyAction=\"").Append(parameters.MethodReplyAction).Append("\"");

```
        }
```
```
        code.AppendLine(")]");
```

        code.Append(parameters.ReturnType).Append(" ");

        code.Append(parameters.MethodName).AppendLine("();");

```
        code.AppendLine("}");
```
```
        code.AppendLine();
```

        code.AppendLine("public class RuntimeServiceClient : ClientBase<IRuntimeService>, IRuntimeService");

```
        code.AppendLine("{");
```

        code.AppendLine("public RuntimeServiceClient(Binding binding, EndpointAddress address) :base(binding, address)");

```
        code.AppendLine("{");
```
```
        code.AppendLine("}");
```

        code.Append("public ").Append(parameters.ReturnType).Append(" ");

        code.Append(parameters.MethodName).AppendLine("()");

```
        code.AppendLine("{");
```

        code.Append("return base.Channel.").Append(parameters.MethodName).AppendLine("();");

```
        code.AppendLine("}");
```
```
        code.AppendLine("}");
```
```
    }
```
```
}
```

注意，红色部分，由于代理类使用了WCF框架，所以编译时我们需要添加System.ServiceModel的引用，当然System.dll肯定是必须的，这里要注意，System.ServiceModel.dll应该保存到应用程序目录，否则动态编译时会引发异常，很简单，在工程引用中添加System.ServiceModel的引用，然后在属性中将拷贝到本地属性设置为true。

到此，我们就可以直接通过传入的服务地址、服务方法名称以及相关的命名空间，即可调用服务(尽管我们只能调用无参服务，并且尽管我们也只能调用使用BasicHttpBinding绑定的服务，这些限制的原因是…我懒，好吧，相信只要经过一点改动即可去掉这些限制)。

可惜，我们的程序还很傻：每次调用服务都需要去生成代码、编译、创建代理实例最后再调用，嗯…那就缓存吧：

在WebServiceParameters类中重写GetHashCode方法：

1:  public override int GetHashCode()

2:  {

3:      return String.Concat(serviceNamespace, methodAction, methodReplyAction, methodName, returnType).GetHashCode();

4:  }

5:

然后在WebServiceProxyCreator中加入缓存机制：

 1:  public class WebServiceProxyCreator

 2:  {

 3:      private static Dictionary<int, Type> proxyTypeCatch = new Dictionary<int, Type>();

4:

 5:      public Object WebServiceCaller(WebServiceParamaters parameters)

 6:      {

 7:          int key = parameters.GetHashCode();

 8:          Type clientType = null;

 9:          if (proxyTypeCatch.ContainsKey(key))

10:          {

11:              clientType = proxyTypeCatch[key];

12:              Debug.WriteLine("使用缓存");

13:          }

14:          else

15:          {

16:

17:              CodeDomProvider provider = CodeDomProvider.CreateProvider("CSharp");

18:              CompilerParameters codeParameters = new CompilerParameters();

19:              codeParameters.GenerateExecutable = false;

20:              codeParameters.GenerateInMemory = true;

21:

22:              StringBuilder code = new StringBuilder();

23:              CreateProxyCode(code, parameters);

24:

25:              codeParameters.ReferencedAssemblies.Add("System.dll");

26:              codeParameters.ReferencedAssemblies.Add("System.ServiceModel.dll");

27:

28:              CompilerResults results = provider.CompileAssemblyFromSource(codeParameters, code.ToString());

29:              Assembly assembly = null;

30:              if (!results.Errors.HasErrors)

31:              {

32:                  assembly = results.CompiledAssembly;

33:              }

34:

35:              clientType = assembly.GetType("RuntimeServiceClient");

36:

37:              proxyTypeCatch.Add(key, clientType);

38:          }

39:          ConstructorInfo ci = clientType.GetConstructor(new Type[] { typeof(Binding), typeof(EndpointAddress) });

40:          BasicHttpBinding binding = new BasicHttpBinding(); //只演示传统的WebService调用

41:          EndpointAddress address = new EndpointAddress(parameters.address);

42:          Object client = ci.Invoke(new object[] { binding, address });

43:

44:          MethodInfo mi = clientType.GetMethod(parameters.MethodName);

45:          Object result = mi.Invoke(client, null);

46:          mi = clientType.GetMethod("Close"); //关闭代理

47:          mi.Invoke(client, null);

48:          return result;

49:      }

50:

51: }

源码下载