C# WinForm 下载文件示例

C# WinForm 下载文件示例

使用 HttpWebRequest 下载文件，参考代码

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);
        }

        /// 
        
        /// c#,.net 下载文件        
        ///         
        /// 下载文件地址
        /// 下载后的存放地址        
        /// 用于显示的进度条
        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;
            }
        }
    }
}

使用 WebClient 组件下载文件，参考代码

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Net;
using System.ServiceProcess;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Test
{
    public partial class FormTest : Form
    {
        private WebClient webClient1 = new WebClient();

        public FormTest()
        {
            InitializeComponent();

            #region 给 webClient1 绑定事件
            {
                this.webClient1.DownloadFileCompleted += new AsyncCompletedEventHandler(this.webClient1_DownloadFileCompleted);
                this.webClient1.DownloadProgressChanged += new DownloadProgressChangedEventHandler(this.webClient1_DownloadProgressChanged);

            }
            #endregion
        }

        /// 

        /// 下载文件
        /// 
        private void DownloadFile()
        {
            // 异步下载文件，可以显示下载进度
            // 如果下载失败或资源有问题等将发生异常
            this.webClient1.DownloadFileAsync(new Uri(url), this.fullName);
        }

        // 文件正在下载时发生
        private void webClient1_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
        {
            // 显示下载进度
            if (this.progressBar1.InvokeRequired)
            {
                this.progressBar1.Invoke(new Action<object, DownloadProgressChangedEventArgs>(this.webClient1_DownloadProgressChanged), sender, e);
            }
            else
            {
                this.progressBar1.Value = e.ProgressPercentage;
            }
        }

        // 文件下载成功时发生
        private void webClient1_DownloadFileCompleted(object sender, AsyncCompletedEventArgs e)
        {
            // 文件下载成功后执行代码
        }
    }
}