WPF桌面端开发11-文件下载

前言

下载工具类，实现了

• 同步异步下载，自动转换线程
• 下载进度条
• 多文件同时下载，定位文件
• 临时文件机制确保下载过程中中断不收影响

工具类

using System;
using System.IO;
using System.Net;
using System.Threading;
using System.Windows.Threading;

namespace z_screen_recorder.Utils
{
    public class ZDownloadUtil
    {
        public static void DownloadFile
        (
            string url,
            string saveFolder
        )
        {
            var path = saveFolder;
            string filename = url.Substring(
                url.LastIndexOf(
                    "/",
                    StringComparison.Ordinal
                ) + 1
            );
            if (!url.StartsWith(
                    "http"
                ) || filename == "")
            {
                return;
            }
            path += filename;
            // 设置参数
            //发送请求并获取相应回应数据
            if (WebRequest.Create(
                    url
                ) is HttpWebRequest request)
            {
                //直到request.GetResponse()程序才开始向目标网页发送Post请求
                if (request.GetResponse() is HttpWebResponse response)
                {
                    Stream responseStream = response.GetResponseStream();

                    //创建本地文件写入流
                    Stream stream = new FileStream(
                        path,
                        FileMode.Create
                    );
                    byte[] bArr = new byte[1024];
                    if (responseStream != null)
                    {
                        int size = responseStream.Read(
                            bArr,
                            0,
                            bArr.Length
                        );
                        while (size > 0)
                        {
                            stream.Write(
                                bArr,
                                0,
                                size
                            );
                            size = responseStream.Read(
                                bArr,
                                0,
                                bArr.Length
                            );
                        }
                    }
                    stream.Close();
                    if (responseStream != null) responseStream.Close();
                }
            }
        }

        /// <summary>
        /// Http下载文件
        /// </summary>
        public static void DownloadFileWithCallback
        (
            string url,
            int tag,
            string saveFolder,
            Dispatcher dispatcher,
            IZDownloadCallback callback
        )
        {
            var path = saveFolder;
            string filename = url.Substring(
                url.LastIndexOf(
                    "/",
                    StringComparison.Ordinal
                ) + 1
            );
            path += filename;
            if (!url.StartsWith(
                    "http"
                ) || filename == "")
            {
                return;
            }
            new Thread(
                o =>
                {
                    FileInfo fi = new FileInfo(
                        path
                    );
                    if (fi.Exists)
                    {
                        dispatcher.Invoke(
                            () =>
                            {
                                callback.DownloadEnd(
                                    tag,
                                    path
                                );
                            }
                        );
                    }
                    else
                    {
                        var temppath = path + ".tmp";
                        dispatcher.Invoke(
                            () =>
                            {
                                callback.DownloadBegin(
                                    tag
                                );
                            }
                        );
                        if (WebRequest.Create(
                                url
                            ) is HttpWebRequest request)
                        {
                            if (request.GetResponse() is HttpWebResponse response)
                            {
                                Stream responseStream = response.GetResponseStream();

                                //创建本地文件写入流
                                Stream stream = new FileStream(
                                    temppath,
                                    FileMode.Create
                                );
                                long totalSize = response.ContentLength;
                                byte[] bArr = new byte[1024];
                                if (responseStream != null)
                                {
                                    int size = responseStream.Read(
                                        bArr,
                                        0,
                                        bArr.Length
                                    );
                                    int readsize = 0;
                                    while (size > 0)
                                    {
                                        readsize += size;
                                        stream.Write(
                                            bArr,
                                            0,
                                            size
                                        );
                                        size = responseStream.Read(
                                            bArr,
                                            0,
                                            bArr.Length
                                        );
                                        var readsize1 = readsize;
                                        dispatcher.Invoke(
                                            () =>
                                            {
                                                callback.DownloadProgress(
                                                    tag,
                                                    (int)(readsize1 * 100 / totalSize)
                                                );
                                            }
                                        );
                                    }
                                }
                                stream.Close();
                                if (responseStream != null) responseStream.Close();
                            }
                        }
                        FileInfo fitemp = new FileInfo(
                            temppath
                        );
                        fitemp.MoveTo(
                            path
                        );
                        dispatcher.Invoke(
                            () =>
                            {
                                callback.DownloadEnd(
                                    tag,
                                    path
                                );
                            }
                        );
                    }
                }
            ).Start();
        }

        public interface IZDownloadCallback
        {
            /// <summary>
            /// 下载开始
            /// </summary>
            /// <param name="tag"></param>
            void DownloadBegin
            (
                int tag
            );

            /// <summary>
            /// 下载过程
            /// </summary>
            /// <param name="tag"></param>
            /// <param name="progress"></param>
            void DownloadProgress
            (
                int tag,
                int progress
            );

            /// <summary>
            /// 下载结束
            /// </summary>
            /// <param name="tag"></param>
            /// <param name="filepath"></param>
            void DownloadEnd
            (
                int tag,
                string filepath
            );
        }
    }
}