场景：为了防止UI卡死，使用异步下载文件

问题：采用多线程下载，关闭窗口后下载线程不能停止，线程操作麻烦。

参考：C#客户端的异步操作：

方案：采用BeginInvoke的方式调用下载方法，委托会自动启动新线程，停止时也不需要手动控制。使用EndInvoke获取返回结果。

try{    IAsyncResult ir = process.BeginInvoke(new HttpDownloadDelegate(HttpDownload),url,path);     bool result = process.EndInvoke(ir);}catch(Exception ex){    MessageBox.Show(ex.Message);}//方法声明public delegate bool HttpDownloadDelegate(string url, string path)public bool HttpDownload(string url, string path){    //下载方法...}

 

HTTP下载：

/// 
        /// http下载文件        /// 
        /// 下载文件地址        /// 文件存放地址，包含文件名        /// 
             public bool HttpDownload(string url, string path)        {            string tempPath = System.IO.Path.GetDirectoryName(path) + @"\temp";            System.IO.Directory.CreateDirectory(tempPath);  //创建临时文件目录            string tempFile = tempPath + @"\" + System.IO.Path.GetFileName(path) + ".temp"; //临时文件            if (System.IO.File.Exists(tempFile))            {                System.IO.File.Delete(tempFile);    //存在则删除            }            try            {                FileStream fs = new FileStream(tempFile, FileMode.Append, FileAccess.Write, FileShare.ReadWrite);                // 设置参数                HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;                //发送请求并获取相应回应数据                HttpWebResponse response = request.GetResponse() as HttpWebResponse;                //直到request.GetResponse()程序才开始向目标网页发送Post请求                Stream responseStream = response.GetResponseStream();                //创建本地文件写入流                //Stream stream = new FileStream(tempFile, FileMode.Create);                byte[] bArr = new byte[1024];                int size = responseStream.Read(bArr, 0, (int)bArr.Length);                while (size > 0)                {                    //stream.Write(bArr, 0, size);                    fs.Write(bArr, 0, size);                    size = responseStream.Read(bArr, 0, (int)bArr.Length);                }                //stream.Close();                fs.Close();                responseStream.Close();                System.IO.File.Move(tempFile, path);                return true;            }            catch (Exception ex)            {                return false;            }        }