C# · 12月 26, 2021

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,(int)by.Length); while (osize > 0) { totalDownloadedByte = osize + totalDownloadedByte; System.Windows.Forms.Application.DoEvents(); so.Write(by,osize); if (prog != null) { prog.Value = (int)totalDownloadedByte; } osize = st.Read(by,(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);}