foreach 内的“跨线程操作无效”

Question

我正在尝试将数据加载到组合框，并且当我运行表单而不进行调试时它正在工作。但是，当我尝试使用调试模式运行它时，出现错误：System.InvalidOperationException：“跨线程操作无效：从创建它的线程以外的线程访问控制“ResultBox”。” 我怎样才能解决这个问题？顺便说一句，有一个后台工作人员在下载数据时写入消息。我在某处读到可以使用后台工作人员解决此问题。这是表单代码：

public Form1()

    {

        InitializeComponent();

        backgroundWorker1.WorkerReportsProgress = true;

    }

    private void Form1_Load(object sender, EventArgs e)

    {

        backgroundWorker1.RunWorkerAsync();

    }

    private Task GetDataTask() {

        return Task.Factory.StartNew(() => {

            List<Result> results = new List<Result>();

            results = 

 GetResults.GetData("http://worldcup.sfg.io/teams/results/");

            foreach (var result in results)

            {

                ResultBox.Items.Add(result.Fifa_Code);

            }

        });

    }

    private void ResultBox_SelectedIndexChanged(object sender, EventArgs e)

    {

    }

    private void SaveTeam_Click(object sender, EventArgs e)

    {

    }

    private async void backgroundWorker1_DoWork(object sender, 

 DoWorkEventArgs e)

    {

        await GetDataTask();

    }

    private void backgroundWorker1_ProgressChanged(object sender, 

 ProgressChangedEventArgs e)

    {

        resultsLoadedLabel.Text = (e.ProgressPercentage.ToString() + "%");

    }

    private void backgroundWorker1_RunWorkerCompleted(object sender, 

 RunWorkerCompletedEventArgs e)

    {

        resultsLoadedLabel.Text = "Podaci učitani!";

    }

foreach 中的这行代码出现异常：

ResultBox.Items.Add(result.Fifa_Code);

这是获得结果的类：

public class GetResults

{

    public static List<Result> GetData(string url) {

        var client = new RestClient();

        var request = new RestRequest(url, Method.GET);

        request.AddHeader("User-Agent", "Nothing");

        IRestResponse<List<Result>> results = client.Execute<List<Result>> 

   (request);

        return results.Data;

    }

}

Answer 1

如果采用异步，则始终采用异步。RestSharp 允许您进行异步调用所以你可以重构数据访问public class GetResults {&nbsp; &nbsp; public static async Task<List<Result>> GetDataAsync(string url) {&nbsp; &nbsp; &nbsp; &nbsp; var client = new RestClient();&nbsp; &nbsp; &nbsp; &nbsp; var request = new RestRequest(url, Method.GET);&nbsp; &nbsp; &nbsp; &nbsp; request.AddHeader("User-Agent", "Nothing");&nbsp; &nbsp; &nbsp; &nbsp; IRestResponse<List<Result>> results = await client.ExecuteTaskAsync<List<Result>>(request);&nbsp; &nbsp; &nbsp; &nbsp; return results.Data;&nbsp; &nbsp; }}接下来，由于表单加载是一个事件处理程序，因此您也可以使其异步并加载数据。public Form1() {&nbsp; &nbsp; InitializeComponent();}private async void Form1_Load(object sender, EventArgs e) {&nbsp; &nbsp; //On UI thread&nbsp; &nbsp; resultsLoadedLabel.Text = "Loading data!";&nbsp; &nbsp; //get data on separate thread (non blocking)&nbsp; &nbsp; List<Result> results = await GetResults.GetDataAsync("http://worldcup.sfg.io/teams/results/");&nbsp; &nbsp; //Back on UI thread&nbsp; &nbsp; resultsLoadedLabel.Text = "Podaci učitani!";&nbsp; &nbsp; foreach (var result in results) {&nbsp; &nbsp; &nbsp; &nbsp; ResultBox.Items.Add(result.Fifa_Code);&nbsp; &nbsp; }}确保在使用异步调用时访问 UI 控件时，可以在创建它们的主线程上访问它们（请参阅注释）。