如何重构 "using" 语句以避免代码重复？

Question

假设我有以下方法：

 public string GetSchedules(string request)
    {
        using (var soapClient = new ServiceReference1.CustomDataTimetableToolKitServicesSoapClient(EndpointConfiguratioName, Endpoint))
        {
            return soapClient.GetSchedules(AuthenticationInfo, request);
        }
    }

    public string GetCountryList(string request)
    {
        using (var soapClient = new ServiceReference1.CustomDataTimetableToolKitServicesSoapClient(EndpointConfiguratioName, Endpoint))
        {
            return soapClient.GetCountryList(AuthenticationInfo, request);
        }
    }

    public string GetCarriers(string request)
    {
        using (var soapClient = new ServiceReference1.CustomDataTimetableToolKitServicesSoapClient(EndpointConfiguratioName, Endpoint))
        {
            return soapClient.GetCarriers(AuthenticationInfo, request);
        }
    }

如您所见，唯一不同的是所调用方法的名称。我如何重构这些方法以仅应用一次 "using" 语句并避免代码重复？

Answer 1

那里确实没有太多重复。不过，

public ServiceReference1.CustomDataTimetableToolKitServicesSoapClient NewClient()
{
    return new ServiceReference1.CustomDataTimetableToolKitServicesSoapClient(EndpointConfiguratioName, Endpoint)
}

using (var client = NewClient()) {
    return soapClient.GetCountryList(AuthenticationInfo, request);
}

此外，由于您的所有方法都采用 string 参数和 return 一个 string，因此很容易编写一个方法来调用它们，传递操作作为代表打电话。很遗憾，我现在没有时间为您写这些。

Answer 2

你可以这样使用lambda函数：

public string GetCarriers(string request)
{
    return Get((authInfo, request) => soapClient.GetCarriers(authInfo, request), request);
}

...

public string Get(Func<AuthenticationInfo, string, string> action, string request) {
    using (var soapClient = new ServiceReference1.CustomDataTimetableToolKitServicesSoapClient(EndpointConfiguratioName, Endpoint))
    {
        return action(AuthenticationInfo, request)
    }
}

我不知道这是否编译，但你明白了。

编辑：正如@Tim S. 所注意到的，这段代码可能会更短：

public string GetCarriers(string request)
{
    return Get(soapClient.GetCarriers, request);
}

...

public string Get(Func<AuthenticationInfo, string, string> action, string request) {
    using (var soapClient = new ServiceReference1.CustomDataTimetableToolKitServicesSoapClient(EndpointConfiguratioName, Endpoint))
    {
        return action(AuthenticationInfo, request)
    }
}

编辑 2：客户端超出范围。所以正确的代码是：

public string GetCarriers(string request)
{
    return Get((client, authInfo, request) => client.GetCarriers(authInfo, request));
}

...

public string Get(Func<ISoapClient, AuthenticationInfo, string, string> action, string request) {
    using (var soapClient = new ServiceReference1.CustomDataTimetableToolKitServicesSoapClient(EndpointConfiguratioName, Endpoint))
    {
        return action(soapClient, AuthenticationInfo, request)
    }
}

Answer 3

对我来说，你所拥有的很好，但如果你想将它们排除在外，你可以使用 Func 和 lambda。沿着这些线的东西：

public string GetSchedules(string request)
{
    return Worker((c) => c.GetSchedules(AuthenticationInfo, request));
}

public string GetCountryList(string request)
{
    return Worker((c) => c.GetCountryList(AuthenticationInfo, request));
}

public string GetCarriers(string request)
{
    return Worker((c) => c.GetCarriers(AuthenticationInfo, request));
}

private string Worker(Func<SoapClientClassGoesHere, string> f)
{
    using (var soapClient = new ServiceReference1.CustomDataTimetableToolKitServicesSoapClient(EndpointConfiguratioName, Endpoint))
    {
        return f(soapClient);
    }
}

Func<A, R> 表示 "a function that takes an argument of type A and returns a value of type R"（对于接受两个参数等的函数，您可以使用 Func<A, B, R>）。

更多关于 Func<> 和 this question and this question 中的 lambda 的信息（以及更多，这是一个内容丰富的主题）。

这是一个 live example on ideone.com（一个非常愚蠢的实例，但它演示了这个概念）：

using System;
using System.Collections.Generic;

class Foo {
    public string GetSchedules(string request)
    {
        return Worker((c) => c[request]);
    }

    public string GetCountryList(string request)
    {
        return Worker((c) => c[request].ToUpper());
    }

    public string GetCarriers(string request)
    {
        return Worker((c) => c[request].ToLower());
    }

    private string Worker(Func<Dictionary<string,string>, string> f)
    {
        var d = new Dictionary<string, string>();
        d.Add("1", "One");
        d.Add("2", "Two");
        d.Add("3", "Three");
        return f(d);
    }
}

public class Test
{
    public static void Main()
    {
        var f = new Foo();
        Console.WriteLine(f.GetSchedules("1"));
        Console.WriteLine(f.GetCountryList("1"));
        Console.WriteLine(f.GetCarriers("1"));
    }
}

Answer 4

如果你的项目不是很大，你可以使用下面的（它有点乱，很容易出错）：

public string getX (string request, string x)
{
    using (var soapClient = new ServiceReference1.CustomDataTimetableToolKitServicesSoapClient(EndpointConfiguratioName, Endpoint))
    {
        switch (x)
        {
            case "schedules":
                return soapClient.GetSchedules(AuthenticationInfo, request);
                break;
            case "countryList":
                return soapClient.GetCountryList(AuthenticationInfo, request);
                break;
            case "carriers":
                return soapClient.GetCarriers(AuthenticationInfo, request);
                break;
            }
        }
    }
}

如何重构 "using" 语句以避免代码重复？

How to refactor "using" statement to avoid code duplication?

c#

wcf

refactoring

using-statement