C# Winform下载文件并显示进度条的实现代码

方法一：

效果如下图所示：

代码如下：

using system;
using system.collections.generic;
using system.componentmodel;
using system.data;
using system.drawing;
using system.linq;
using system.text;
using system.windows.forms;

namespace winshowdown
{
 public partial class frmmain : form
 {
  public frmmain()
  {
   initializecomponent();
  }

  private void btndown_click(object sender, eventargs e)
  {
   downloadfile("http://localhost:1928/webserver/downloader/123.rar", @"c:\123.rar", progressbar1, label1);
  }
  /// <summary>  
  /// c#,.net 下载文件  
  /// </summary>  
  /// <param name="url">下载文件地址</param>  
  /// 
  /// <param name="filename">下载后的存放地址</param>  
  /// <param name="prog">用于显示的进度条</param>  
  /// 
  public void downloadfile(string url, string filename, system.windows.forms.progressbar prog, system.windows.forms.label label1)
  {
   float percent = 0;
   try
   {
    system.net.httpwebrequest myrq = (system.net.httpwebrequest)system.net.httpwebrequest.create(url);
    system.net.httpwebresponse myrp = (system.net.httpwebresponse)myrq.getresponse();
    long totalbytes = myrp.contentlength;
    if (prog != null)
    {
     prog.maximum = (int)totalbytes;
    }
    system.io.stream st = myrp.getresponsestream();
    system.io.stream so = new system.io.filestream(filename, system.io.filemode.create);
    long totaldownloadedbyte = 0;
    byte[] by = new byte[1024];
    int osize = st.read(by, 0, (int)by.length);
    while (osize > 0)
    {
     totaldownloadedbyte = osize + totaldownloadedbyte;
     system.windows.forms.application.doevents();
     so.write(by, 0, osize);
     if (prog != null)
     {
      prog.value = (int)totaldownloadedbyte;
     }
     osize = st.read(by, 0, (int)by.length);

     percent = (float)totaldownloadedbyte / (float)totalbytes * 100;
     label1.text = "当前补丁下载进度" + percent.tostring() + "%";
     system.windows.forms.application.doevents(); //必须加注这句代码，否则label1将因为循环执行太快而来不及显示信息
    }
    so.close();
    st.close();
   }
   catch (system.exception)
   {
    throw;
   }
  }
 }
}

实现方法二：

winform下载文件并显示下载进度示例

/// <summary>
/// 显示进度
/// </summary>
/// <param name="val"></param>
private void progressbar_value(int val)
{
 progressbar1.value = val;
 label1.text = val.tostring() + "%";
}

/// <summary>
/// 下载文件
/// </summary>
/// <param name="url"></param>
/// <param name="savefile"></param>
/// <param name="downloadprogresschanged"></param>
/// <param name="downloadfilecompleted"></param>
private void downloadfile(string url, string savefile, action<int> downloadprogresschanged, action downloadfilecompleted)
{
 webclient client = new webclient();
 if (downloadprogresschanged != null)
 {
  client.downloadprogresschanged += delegate(object sender, downloadprogresschangedeventargs e)
  {
   this.invoke(downloadprogresschanged, e.progresspercentage);
  };
 }
 if (downloadfilecompleted != null)
 {
  client.downloadfilecompleted += delegate(object sender, asynccompletedeventargs e)
  {
   this.invoke(downloadfilecompleted);
  };
 }
 client.downloadfileasync(new uri(url), savefile);
}
delegate void action(); //.net framework 2.0得自定义委托action

/// <summary>
/// 点击下载
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void button1_click(object sender, eventargs e)
{
 downloadfile("http://xiazai.jb51.net/update.zip", @"f:update.zip", progressbar_value, null);
}