解决　vs2005编译错误提示 "how to make cross-thread calls"超简单实例

这两天在学习WebRequest Web Response对header操作时，涉及到异步操作，按实例运行出错，vs2005提示“how to make cross-thread calls...”，查了一下资料。将原来的代码

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using System;


using System.IO;


using System.Collections.Generic;


using System.ComponentModel;


using System.Data;


using System.Drawing;


using System.Text;


using System.Windows.Forms;


using System.Net;




namespace Accessing_the_internet




...{


public partial class Form1 : Form




...{


public Form1()




...{


InitializeComponent();




WebRequest wrq = WebRequest.Create("http://www.123de6.cn");


wrq.BeginGetResponse(new AsyncCallback(OnResponse), wrq);


}


protected void OnResponse(IAsyncResult ar)




...{


WebRequest wrq=(WebRequest)ar.AsyncState;


WebResponse wrs=wrq.EndGetResponse(ar);





//read the response


WebHeaderCollection whc = wrs.Headers;


MethodInvoker mi=new MethodInvoker()





for (int i = 0; i < whc.Count; i++)




...{


listBox1.Items.Add("Header"+ whc.GetKey(i)+" : " +whc[i]);


}


}








}




}

改为这样，就可以实现对主线程listbox的操作。




using System;


using System.IO;


using System.Collections.Generic;


using System.ComponentModel;


using System.Data;


using System.Drawing;


using System.Text;


using System.Windows.Forms;


using System.Net;




namespace Accessing_the_internet




...{


public partial class Form1 : Form




...{


WebHeaderCollection whc;


public Form1()




...{


InitializeComponent();




WebRequest wrq = WebRequest.Create("http://www.123de6.cn");


wrq.BeginGetResponse(new AsyncCallback(OnResponse), wrq);


}


protected void OnResponse(IAsyncResult ar)




...{


WebRequest wrq=(WebRequest)ar.AsyncState;


WebResponse wrs=wrq.EndGetResponse(ar);





//read the response


whc = wrs.Headers;


MethodInvoker mi = new MethodInvoker(controla);


this.BeginInvoke(mi);








}


private void controla()




...{


for (int i = 0; i < whc.Count; i++)




...{




listBox1.Items.Add("Header" + whc.GetKey(i) + " : " + whc[i]);


}


}





}





}