C#下载文件函数

using system;
using system.drawing;
using system.collections;
using system.componentmodel;
using system.windows.forms;
using system.net;
using system.io;
using system.text;

private void button3_click(object sender, system.eventargs e)
  {
   string downloadurl=textbox3.text;
   string localpath=textbox4.text;
   if(downfile(downloadurl,localpath))
   {
   messagebox.show("下载完成");
   }
   else
   {
   messagebox.show("下载过程中出现错误:");
   }
  }
  public bool downfile(string url,string localpath)
  {
   try
   {
    uri u = new uri(url);
    httpwebrequest mrequest = (httpwebrequest)webrequest.create(u);
    mrequest.method = "get";
    mrequest.contenttype = "application/x-www-form-urlencoded";

    httpwebresponse wr = (httpwebresponse)mrequest.getresponse();

    stream sin = wr.getresponsestream();
    filestream fs = new filestream(localpath, filemode.create, fileaccess.write);

    long length = wr.contentlength;
    long i = 0;
    decimal j=0;
    
    while (i < length)
    {
     byte[] buffer = new byte[1024];
     i += sin.read(buffer, 0, buffer.length);
     fs.write(buffer, 0, buffer.length);
     
     if((i % 1024)==0)
     {
      j=math.round(convert.todecimal((convert.todouble(i)/convert.todouble(length))*100),4);
      statusbar1.text="当前下载文件大小:"+length.tostring()+"字节   当前下载大小:"+i+"字节 下载进度"+j.tostring()+"%";
      
     }
     else
     {
      statusbar1.text="当前下载文件大小:"+length.tostring()+"字节   当前下载大小:"+i+"字节";
     }
     
    }

    sin.close();
    wr.close();
    fs.close();
    return true;
   }
   catch { return false; }
  }