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);
}