C#異步批量下載文件

實現原理：采用WebClient進行批量下載任務，簡單的模擬迅雷下載效果！

廢話不多說,先看掩飾效果：

具體實現步驟如下：

1.新建項目：WinBatchDownload

2.先建一個Windows窗體：FrmBatchDownload,加載事件FrmBatchDownload_Load

3.放置一個Button按鈕：btnStartDownLoad,單機事件btnStartDownLoad_Click

4.放置一個DataGridView：dgvDownLoad.

5.具體代碼如下：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
#region 命名空間

using System.Threading;
using System.Runtime.InteropServices;
using System.Net;
using System.Collections;

#endregion

namespace WinBatchDownload
{
    public partial class FrmBatchDownload : Form
    {
        #region 全局成員

        //存放下載列表
        List<SynFileInfo> m_SynFileInfoList;

        #endregion

        #region 構造函數

        public FrmBatchDownload()
        {
            InitializeComponent();
            m_SynFileInfoList = new List<SynFileInfo>();
        }

        #endregion

        #region 窗體加載事件

        private void FrmBatchDownload_Load(object sender, EventArgs e)
        {
            //初始化DataGridView相關屬性
            InitDataGridView(dgvDownLoad);
            //添加DataGridView相關列信息
            AddGridViewColumns(dgvDownLoad);
            //新建任務
            AddBatchDownload();
        }

        #endregion

        #region 添加GridView列

        /// <summary>
        /// 正在同步列表
        /// </summary>
        void AddGridViewColumns(DataGridView dgv)
        {
            dgv.Columns.Add(new DataGridViewTextBoxColumn()
            {
                DataPropertyName = "DocID",
                HeaderText = "文件ID",
                Visible = false,
                Name = "DocID"
            });
            dgv.Columns.Add(new DataGridViewTextBoxColumn()
            {
                AutoSizeMode = DataGridViewAutoSizeColumnMode.None,
                DataPropertyName = "DocName",
                HeaderText = "文件名",
                Name = "DocName",
                Width = 300
            });
            dgv.Columns.Add(new DataGridViewTextBoxColumn()
            {
                DataPropertyName = "FileSize",
                HeaderText = "大小",
                Name = "FileSize",
            });
            dgv.Columns.Add(new DataGridViewTextBoxColumn()
            {
                DataPropertyName = "SynSpeed",
                HeaderText = "速度",
                Name = "SynSpeed"
            });
            dgv.Columns.Add(new DataGridViewTextBoxColumn()
            {
                DataPropertyName = "SynProgress",
                HeaderText = "進度",
                Name = "SynProgress"
            });
            dgv.Columns.Add(new DataGridViewTextBoxColumn()
            {
                DataPropertyName = "DownPath",
                HeaderText = "下載地址",
                Visible = false,
                Name = "DownPath"
            });
            dgv.Columns.Add(new DataGridViewTextBoxColumn()
            {
                DataPropertyName = "SavePath",
                HeaderText = "保存地址",
                Visible = false,
                Name = "SavePath"
            });
            dgv.Columns.Add(new DataGridViewTextBoxColumn()
            {
                DataPropertyName = "Async",
                HeaderText = "是否異步",
                Visible = false,
                Name = "Async"
            });
        }

        #endregion

        #region 添加下載任務並顯示到列表中

        void AddBatchDownload()
        {
            //清空行數據
            dgvDownLoad.Rows.Clear();
            //添加列表(建立多個任務)
            List<ArrayList> arrayListList = new List<ArrayList>();
            arrayListList.Add(new ArrayList(){
                "0",//文件id
                "PPTV客戶端.exe",//文件名稱
                "21.2 MB",//文件大小
                "0 KB/S",//下載速度
                "0%",//下載進度
                "http://download.pplive.com/pptvsetup_3.2.1.0076.exe",//遠程服務器下載地址
                "D:\\PPTV客戶端.exe",//本地保存地址
                true//是否異步
            });
            arrayListList.Add(new ArrayList(){
                "1",
                "PPS客戶端.exe",
                "14.3 MB",
                "0 KB/S",
                "0%",
                "http://download.ppstream.com/ppstreamsetup.exe",
                "D:\\PPS客戶端.exe",
                true
            });
            arrayListList.Add(new ArrayList(){
                "2",
                "美圖看看客戶端.exe",
                "4.1 MB",
                "0 KB/S",
                "0%",
                "http://kankan.dl.meitu.com/V2/1029/KanKan_kk360Setup.exe",
                "D:\\美圖看看客戶端.exe",
                true
            });
            foreach (ArrayList arrayList in arrayListList)
            {
                int rowIndex = dgvDownLoad.Rows.Add(arrayList.ToArray());
                arrayList[2] = 0;
                arrayList.Add(dgvDownLoad.Rows[rowIndex]);
                //取出列表中的行信息保存列表集合(m_SynFileInfoList)中
                m_SynFileInfoList.Add(new SynFileInfo(arrayList.ToArray()));
            }
        }

        #endregion

        #region 開始下載按鈕單機事件

        private void btnStartDownLoad_Click(object sender, EventArgs e)
        {
            //判斷網絡連接是否正常
            if (isConnected())
            {
                //設置不可用
                btnStartDownLoad.Enabled = false;
                //設置最大活動線程數以及可等待線程數
                ThreadPool.SetMaxThreads(3, 3);
                //判斷是否還存在任務
                if (m_SynFileInfoList.Count <= 0) AddBatchDownload();
                foreach (SynFileInfo m_SynFileInfo in m_SynFileInfoList)
                {
                    //啟動下載任務
                    StartDownLoad(m_SynFileInfo);
                }
            }
            else
            {
                MessageBox.Show("網絡異常!");
            }
        }

        #endregion

        #region 檢查網絡狀態

        //檢測網絡狀態
        [DllImport("wininet.dll")]
        extern static bool InternetGetConnectedState(out int connectionDescription, int reservedValue);
        /// <summary>
        /// 檢測網絡狀態
        /// </summary>
        bool isConnected()
        {
            int I = 0;
            bool state = InternetGetConnectedState(out I, 0);
            return state;
        }

        #endregion

        #region 使用WebClient下載文件

        /// <summary>
        /// HTTP下載遠程文件並保存本地的函數
        /// </summary>
        void StartDownLoad(object o)
        {
            SynFileInfo m_SynFileInfo = (SynFileInfo)o;
            m_SynFileInfo.LastTime = DateTime.Now;
            //再次new 避免WebClient不能I/O並發 
            WebClient client = new WebClient();
            if (m_SynFileInfo.Async)
            {
                //異步下載
                client.DownloadProgressChanged += new DownloadProgressChangedEventHandler(client_DownloadProgressChanged);
                client.DownloadFileCompleted += new AsyncCompletedEventHandler(client_DownloadFileCompleted);
                client.DownloadFileAsync(new Uri(m_SynFileInfo.DownPath), m_SynFileInfo.SavePath, m_SynFileInfo);
            }
            else client.DownloadFile(new Uri(m_SynFileInfo.DownPath), m_SynFileInfo.SavePath);
        }

        /// <summary>
        /// 下載進度條
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        void client_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
        {
            SynFileInfo m_SynFileInfo = (SynFileInfo)e.UserState;
            m_SynFileInfo.SynProgress = e.ProgressPercentage + "%";
            double secondCount = (DateTime.Now - m_SynFileInfo.LastTime).TotalSeconds;
            m_SynFileInfo.SynSpeed = FileOperate.GetAutoSizeString(Convert.ToDouble(e.BytesReceived / secondCount), 2) + "/s";
            //更新DataGridView中相應數據顯示下載進度
            m_SynFileInfo.RowObject.Cells["SynProgress"].Value = m_SynFileInfo.SynProgress;
            //更新DataGridView中相應數據顯示下載速度(總進度的平均速度)
            m_SynFileInfo.RowObject.Cells["SynSpeed"].Value = m_SynFileInfo.SynSpeed;
        }

        /// <summary>
        /// 下載完成調用
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        void client_DownloadFileCompleted(object sender, AsyncCompletedEventArgs e)
        {
            //到此則一個文件下載完畢
            SynFileInfo m_SynFileInfo = (SynFileInfo)e.UserState;
            m_SynFileInfoList.Remove(m_SynFileInfo);
            if (m_SynFileInfoList.Count <= 0)
            {
                //此時所有文件下載完畢
                btnStartDownLoad.Enabled = true;
            }
        }

        #endregion

        #region 需要下載文件實體類

        class SynFileInfo
        {
            public string DocID { get; set; }
            public string DocName { get; set; }
            public long FileSize { get; set; }
            public string SynSpeed { get; set; }
            public string SynProgress { get; set; }
            public string DownPath { get; set; }
            public string SavePath { get; set; }
            public DataGridViewRow RowObject { get; set; }
            public bool Async { get; set; }
            public DateTime LastTime { get; set; }

            public SynFileInfo(object[] objectArr)
            {
                int i = 0;
                DocID = objectArr[i].ToString(); i++;
                DocName = objectArr[i].ToString(); i++;
                FileSize = Convert.ToInt64(objectArr[i]); i++;
                SynSpeed = objectArr[i].ToString(); i++;
                SynProgress = objectArr[i].ToString(); i++;
                DownPath = objectArr[i].ToString(); i++;
                SavePath = objectArr[i].ToString(); i++;
                Async = Convert.ToBoolean(objectArr[i]); i++;
                RowObject = (DataGridViewRow)objectArr[i];
            }
        }

        #endregion

        #region 初始化GridView

        void InitDataGridView(DataGridView dgv)
        {
            dgv.AutoGenerateColumns = false;//是否自動創建列
            dgv.AllowUserToAddRows = false;//是否允許添加行(默認：true)
            dgv.AllowUserToDeleteRows = false;//是否允許刪除行(默認：true)
            dgv.AllowUserToResizeColumns = false;//是否允許調整大小(默認：true)
            dgv.AllowUserToResizeRows = false;//是否允許調整行大小(默認：true)
            dgv.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.Fill;//列寬模式(當前填充)(默認：DataGridViewAutoSizeColumnsMode.None)
            dgv.BackgroundColor = System.Drawing.Color.White;//背景色(默認：ControlDark)
            dgv.BorderStyle = BorderStyle.Fixed3D;//邊框樣式(默認：BorderStyle.FixedSingle)
            dgv.CellBorderStyle = DataGridViewCellBorderStyle.SingleHorizontal;//單元格邊框樣式(默認：DataGridViewCellBorderStyle.Single)
            dgv.ColumnHeadersBorderStyle = DataGridViewHeaderBorderStyle.None;//列表頭樣式(默認：DataGridViewHeaderBorderStyle.Single)
            dgv.ColumnHeadersHeightSizeMode = DataGridViewColumnHeadersHeightSizeMode.DisableResizing;//是否允許調整列大小(默認：DataGridViewColumnHeadersHeightSizeMode.EnableResizing)
            dgv.ColumnHeadersHeight = 30;//列表頭高度(默認：20)
            dgv.MultiSelect = false;//是否支持多選(默認：true)
            dgv.ReadOnly = true;//是否只讀(默認：false)
            dgv.RowHeadersVisible = false;//行頭是否顯示(默認：true)
            dgv.SelectionMode = DataGridViewSelectionMode.FullRowSelect;//選擇模式(默認：DataGridViewSelectionMode.CellSelect)
        }

        #endregion

        #region 文件相關操作類分

        /// <summary>
        /// 文件有關的操作類
        /// </summary>
        public class FileOperate
        {
            #region 相應單位轉換常量

            private const double KBCount = 1024;
            private const double MBCount = KBCount * 1024;
            private const double GBCount = MBCount * 1024;
            private const double TBCount = GBCount * 1024;

            #endregion

            #region 獲取適應大小

            /// <summary>
            /// 得到適應大小
            /// </summary>
            /// <param name="size">字節大小</param>
            /// <param name="roundCount">保留小數(位)</param>
            /// <returns></returns>
            public static string GetAutoSizeString(double size, int roundCount)
            {
                if (KBCount > size) return Math.Round(size, roundCount) + "B";
                else if (MBCount > size) return Math.Round(size / KBCount, roundCount) + "KB";
                else if (GBCount > size) return Math.Round(size / MBCount, roundCount) + "MB";
                else if (TBCount > size) return Math.Round(size / GBCount, roundCount) + "GB";
                else return Math.Round(size / TBCount, roundCount) + "TB";
            }

            #endregion
        }

        #endregion
    }
}

　源碼：https://github.com/marblemm/WinBatchDownload