Question

我有一些使用网络服务的代码。我不是每次都从服务中检索会话密钥，而是想用我设置的会话变量来尝试响应，如果我收到403错误，请获取新的会话密钥并重试。

在我有限的思维中，嵌套try/catch语句很有意义，但我只是意识到必须有更好的方法。我在这里读过一些提及lambda expressions with using statements和Helpers之类的帖子，但这些也可能是外星人间行星科学给我的礼物。

总是愿意学习我想知道是否有人有建议（详情或细节链接）？这里的一切都有效，我只需要比嵌套try语句更好的方法（请和谢谢）。一如既往，你们摇滚！

如果没有设置会话密钥，

public string getMySessionkey将使用登录凭据进入服务器以获取会话密钥（所有其他查询都需要）

searchPacket = stringbuilder with parameters and session key

if (Session["MySessionKey"] != null)
{
    sessionKee = Session["MySessionKey"].ToString();
}
else
{
    sessionKee = getMySessionkey(_cbE, _cbP);
    System.Web.HttpContext.Current.Session.Add("MySessionKey", sessionKee);
}

try
{
    mySearchResults = getResults(searchPacket.ToString());
    vbResultz += Server.HtmlEncode(mySearchResults) ;
}
catch (WebException wx)
{
    HttpWebResponse webresponse ;
    webresponse = (HttpWebResponse)wx.Response;

    switch (webresponse.StatusCode)
    {
       case HttpStatusCode.InternalServerError:
            ...
            break;

        case HttpStatusCode.Forbidden: // 403
            vbResultz = "You aint got no valid session key!";
          // code here to get a new session key and try again

            break;

        default:
            throw;
    }
}

Answer 1

使用具有有限出现次数的循环。只要您的通话有效，请退出循环。

var maxNumberOfTries = 3;
var currentTry = 0;
var success = false;

do
{
    currentTry += 1;

    // Try whatever here. If it works, set success variable to true

    if (success) break;
} while (currentTry <= maxNumberOfTries)

if (!success)
{
    // If code reaches here, whatever had to be done has been tried <maxNumberOfTries> times and did not work
}

编辑：以下是您的代码中实现的上述示例：

var maxNumberOfTries = 3;
var currentTry = 0;
var flag = false;

do
{
    currentTry += 1;

    try
    {
        mySearchResults = getResults(searchPacket.ToString());
        vbResultz += Server.HtmlEncode(mySearchResults) ;
        flag = true;
    }
    catch (WebException wx)
    {
        HttpWebResponse webresponse ;
        webresponse = (HttpWebResponse)wx.Response;

        switch (webresponse.StatusCode)
        {
           case HttpStatusCode.InternalServerError:
            ...
                flag = true;
                break;

            case HttpStatusCode.Forbidden: // 403
                vbResultz = "You aint got no valid session key!";
              // code here to get a new session key and try again

                break;

            default:
                throw;
        }
    }
    if (flag) break;
} while (currentTry <= maxNumberOfTries)

if (!flag)
{
    // If code reaches here, whatever had to be done has been tried <maxNumberOfTries> times and did not work
}

在成功尝试获取密钥时，flag变量将设置为true，或者如果发生内部服务器错误，则将其设置为true。如果您有403响应，它将再次尝试，最多三次。

嵌套的Try / Catch语句替代方案

1 个答案: