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

<script type="text/javascript" src="http://pagead2.googlesyndication.com/pagead/show_ads.js"> </script>

 

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]);
            }
        }
           
     }
    
}