c# - 类设计——如何管理多线程响应

Question

我需要一些帮助，了解如何最好地设计一组类来管理我正在开发的多线程 C# 应用程序。我已经成功地创建了一个启动一系列线程的 ThreadContainer 类。Threads 从特定网站下载财务数据。对于每个通过的网站，他们将打开相同的基本 url，但使用不同的符号。所以有 # 个结果等于每个网站传递的符号数。然后根据请求的网站，线程结果必须以不同的方式处理......这是简化的 ThreadContainer 代码:

public class ThreadContainer
{
private int ConcurrentThreads;
private string Website;
public string URL;
private Queue SymQueue;

//Constructor
public ThreadContainer(string website, Queue symQueue)
{
   Website = website;
   SymQueue = symQueue;
}

//Start
public void start(int concurrent)
{
    ConcurrentThreads = concurrent;

    //Start the Concurrent Threads
    for (int ThreadNum = 1; ThreadNum <= ConcurrentThreads; ThreadNum++)
    {   
        //Get a symbol from the queue
        Sym = SymQueue.Dequeue().ToString(); 

        //Build the URL
        URL = string.Format(Constants.URL(Website), Sym);

        //Create a new Asynch thread 
        AsynchThread j = new AsynchThread(ThreadNum);

        //Start the AsyncThread class with the BackgoundWorker
        j.Start(Sym, URL);
    }
}

//Method called when the Backgroundworker thread has terminated 
private void AsynchThread1_JobCompleted(object sender, EventArgs e)
{
    // Get the AsynchThread object
    AsynchThread j = (AsynchThread)sender;

        //Get the symbol name
        String Sym = j.Sym;

        //Get the result with the Webpage content
        RunWorkerCompletedEventArgs re = e as RunWorkerCompletedEventArgs;
        String result = re.Result.ToString();

        /* HERE EACH THREAD RETURNS THE WEBSITE CONTENT.
         * DEPENDING ON THE WEBSITE THAT WAS REQUESTED SEVERAL ACTIONS MAY BE EXECUTED.
        */
        switch(website)
        {
            case "WebsiteA":
                // With WebsiteA I would like to :
                // 1. extract the symbol data
                // 2. return the result for this symbol to the calling class.

            case "WebsiteB":
                // With WebsiteB I would like to:
                // 1. extract the symbol data (Webpage design is different from WebsiteA)
                // 2. store each symbol data in a database table

            case "WebsiteC":
                // With WebsiteB I would like to:
                // 1. extract the symbol data (Webpage design is different from WebsiteA and WebsiteB)
                // 2. put the results in a queue 

            case ...

            default:            
                return "";
        }        

        // Reuse the thread that has just completed
        //If there are items left in the queue...
        if (SymQueue.Count > 0)
            //...get the new Sym value...
            NewSym = SymQueue.Dequeue().ToString();

        //If NewSym is valid ...
        if (!String.IsNullOrEmpty(NewSym))
        {
            //...build the URL...
            String NewURL = string.Format(Constants.URL(Website), NewSym);

            //...then restart the thread with the new parameters
            j.Start(NewSym, NewURL);
        }    
    }
}

我想知道设计AsynchThread1_JobCompleted 的最佳方法是什么方法。当每个线程终止并应执行以下任务时调用此方法:

1. 获取网页内容
2. 从网页中提取数据
3. 将数据发送回调用者或​​将数据保存到数据库或将数据插入队列。
4. 检查队列是否还有项目并使用新 URL 重新启动线程，以便打开新网页。

我该如何设计方法，才不必每次需要添加新网站时都修改代码？另外，我应该使用下载页面的同一个 AsynchThread 来提取数据，保存到数据库等......还是另一个线程更好？我想让 ThreadContainer 类遵循一种单一职责原则...

谢谢

Answer 1

在 EventArgs 中，将委托(delegate)/操作传递给处理此站点的特定实现。

或者更好地隔离一个类站点，在其中放置 url 和方法来处理要对数据完成的特定工作。然后在线程的EventArgs中传入Site，在回调中调用该Site的具体方法。

这样您将删除 case 语句，并将代码移到它所属的位置。