后台字典加载

Question

这看起来应该如此简单，但显然并非如此。

我有一本字典，需要在程序启动时加载40000个条目。它只延迟5-7秒的加载时间，但我想在后台这样做，以避免这种情况。

在下面的代码中，有三个部分处理我目前拥有的dictionary和BackgroundWorker。

我知道这段代码使它成为PopulateZipCodeDictionary()方法，但出于某种原因，它实际上并没有启动该方法。

我做错了什么？

    static BackgroundWorker populateZipCodeDictionary;

    public MainWindow()
    {
        populateZipCodeDictionary = new BackgroundWorker();
        populateZipCodeDictionary.DoWork += populateZipCodeDictionary_DoWork;
        populateZipCodeDictionary.RunWorkerCompleted += populateZipCodeDictionary_RunWorkerCompleted;
        populateZipCodeDictionary.RunWorkerAsync();         
    }

    static void populateZipCodeDictionary_DoWork(object sender, DoWorkEventArgs e)
    {
        ZipCodes.PopulateZipCodeDictionary();
    }

    static void populateZipCodeDictionary_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        MessageBox.Show("Dictionary loaded");
    }

static class ZipCodes
{
    #region Methods
    public static string GetValue(string key)
    {
        string result;
        if (zipCodeDictionary.TryGetValue(key, out result))
        {
            return result;
        }
        else
        {
            return null;
        }
    }
    #endregion


    #region ZipCode Dictionary Definition
    static Dictionary<string, string> zipCodeDictionary = new Dictionary<string, string>();

    public static void PopulateZipCodeDictionary()
    {
        zipCodeDictionary.Add( "00501", "Holtsville, NY" );
        zipCodeDictionary.Add( "00544", "Holtsville, NY" );
        zipCodeDictionary.Add( "00601", "Adjuntas, PR" );
        zipCodeDictionary.Add( "00602", "Aguada, PR" );
        zipCodeDictionary.Add( "00603", "Aguadilla, PR" );
        zipCodeDictionary.Add( "00604", "Aguadilla, PR" );
        //Continues on adding ~40k entries...
    }

Answer 1

这是一个用于后台处理的例程。您只需在处理完成时给RunBehind一个要执行的操作和一个要调用的操作。

public class Worker
{
    private Dispatcher _appDispatcher = Dispatcher.CurrentDispatcher;
    private Dispatcher _workerDispatcher;
    private Thread _workerThread;

    public Worker()
    {
        _workerThread = new Thread(RunWorkerThread);
        _workerThread.Start();
    }

    public void RunBehind(Action a_action, Action a_callback)
    {
        _workerDispatcher.BeginInvoke(new Action(() =>
        {
            a_action();
            _appDispatcher.BeginInvoke(a_callback);
        }));
    }

    private void RunWorkerThread()
    {
        Thread.CurrentThread.Name = "AppWorker";
        _workerDispatcher = Dispatcher.CurrentDispatcher;

        Dispatcher.Run();
    }
}

也许试着锁上..。

static class ZipCodes
{
    private static Object zipLocker = new Object();

    #region Methods
    public static string GetValue(string key)
    {
        lock (zipLocker)
        {
            string result;
            if (zipCodeDictionary.TryGetValue(key, out result))
            {
                return result;
            }
            else
            {
                return null;
            }
        }
    }
    #endregion


    #region ZipCode Dictionary Definition
    static Dictionary<string, string> zipCodeDictionary = null;

    public static void PopulateZipCodeDictionary()
    {
        Dictionary<string, string> workingDictionary = new Dictionary<string, string>();

        workingDictionary.Add( "00501", "Holtsville, NY" );
        workingDictionary.Add( "00544", "Holtsville, NY" );
        workingDictionary.Add( "00601", "Adjuntas, PR" );
        workingDictionary.Add( "00602", "Aguada, PR" );
        workingDictionary.Add( "00603", "Aguadilla, PR" );
        workingDictionary.Add( "00604", "Aguadilla, PR" );
        //Continues on adding ~40k entries...

        lock (zipLocker)
        {
            zipCodeDictionary = workingDictionary;
        }
    }
}

Answer 2

我只看到两种情况：

1. DoWork事件处理程序实际上已被执行，您不知怎么忽略了这一点，放置一个断点将是查看实际情况的最有效方法。
2. 引发了一些问题，因此在事件args中引发了一个错误的RunWorkerCompleted事件。

MSDN，BackgroundWorker.RunWorkerCompleted事件

在后台操作完成、已取消或引发异常时发生。System.ComponentModel.RunWorkerCompletedEventArgs的错误属性指示操作引发异常。

Answer 3

尝试将已完成的事件处理程序更改为：

static void populateZipCodeDictionary_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
    if (e.Error != null)
        MessageBox.Show(e.Error.ToString());
    else
        MessageBox.Show("Dictionary loaded");
}

我猜您的DoWork处理程序正在抛出一个异常。