c# - 处理条件语句的最佳方法

Question

我在我的代码中使用了以下条件，但看起来效率不高，这是更好的处理方式吗？

if (ic = filename.Contains(".wmv"))
{
    if (bitnumber > 400)
    {
        path = "ftp://" + ftpServerIP + "/" + "media" + "/" + "lib" + "/" + programName + "/" + date + "/";
        UploadCondition(path, filename);
        //return path;
    }
}

if (ic = filename.Contains(".wmv"))
{
    if (bitnumber < 400)
    {
        path = "ftp://" + ftpServerIP + "/" + "mpegmedia" + "/" + "news" + "/" + programName + "/" + "video" + "/" + "podcast" + "/";
        UploadCondition(path, filename);
        //return path;
    }
}

if (ic = filename.Contains(".m4v"))
{
    path = "ftp://" + ftpServerIP + "/" + "mpegmedia" + "/" + "news" + "/" + programName + "/" + "video" + "/" + "podcast" + "/";
    UploadCondition(path, filename);
}

if (ic = filename.Contains(".mp4"))
{
    path = "ftp://" + ftpServerIP + "/" + "mpegmedia" + "/" + "news" + "/" + programName + "/" + "video" + "/" + "podcast" + "/";
    UploadCondition(path, filename);
}
if (ic = filename.Contains(".flv"))
{
    path = "ftp://" + ftpServerIP + "/" + "mpegmedia" + "/" + "news" + "/" + programName + "/" + "video" + "/" + "podcast" + "/";
    UploadCondition(path, filename);
}
if (ic = filename.Contains(".mpg"))
{
    path = "ftp://" + ftpServerIP + "/" + "mpegmedia" + "/" + "news" + "/" + programName + "/" + "video" + "/" + "podcast" + "/";
    UploadCondition(path, filename);
}
if (ic = filename.Contains(".aac"))
{
    path = "ftp://" + ftpServerIP + "/" + "mpegmedia" + "/" + "news" + "/" + programName + "/" + "audio" + "/" + "podcast" + "/";
    UploadCondition(path, filename);
}
if (ic = filename.Contains(".mp3"))
{
    path = "ftp://" + ftpServerIP + "/" + "mpegmedia" + "/" + "news" + "/" + programName + "/" + "audio" + "/" + "podcast" + "/";
    UploadCondition(path, filename);
}

Answer 1

在其他类中分解它，例如:

public class AudioFileValidator
{
    private List<string> _extensions = new List<string>{".aac", ".mp3"};
    public bool IsValid(string filename)
    {
        if (!_extensions.Contains(Path.GetExtension(filename))
            return false;

        //validate bitrate etc
    }
}

用法:

var audioValidator = new AudioFileValidator();
if (audioValidator.IsValid(filename)) 
{
    path = "ftp://" + ftpServerIP + "/" + "mpegmedia" + "/" + "news" + "/" + programName + "/" + "audio" + "/" + "podcast" + "/";
    UploadCondition(path, filename);
}

var videoValidator = new VideoFileValidator();
if (videoValidator.IsValid(filename)) 
{
    path = "ftp://" + ftpServerIP + "/" + "mpegmedia" + "/" + "news" + "/" + programName + "/" + "video" + "/" + "podcast" + "/";
    UploadCondition(path, filename);
}

通过这样做，您将获得具有单一职责的类，这些类可以在其他地方重用并且易于进行单元测试。

---

您甚至可以更进一步，引入一个名为 IMediaFileValidator 的新接口(interface)，所有验证器都实现该接口(interface)。并做类似的事情:

foreach (var validator in validators)
{ 
    if (validator.IsValid(filename))
    {
        // use info from the validator to build the path
        var mediaName = validator.MediaName; 
        path = "ftp://" + ftpServerIP + "/" + mediaName + "/" + "news" + "/" + programName + "/" + "video" + "/" + "podcast" + "/";
        UploadCondition(path, filename);
        break;
    }
}

这也会使您的代码遵守开放/封闭原则。