C#根据输入参数从url下载zip文件

Question

我有一个要求,我必须根据输入参数使用c#(大小可以在10mb到400mb之间)下载一个zip文件.例如,下载userId = 10和year = 2012
的报告.Web 服务器接受这两个参数并返回一个zip文件.如何使用WebClient类实现此目的？
谢谢

Answer 1

您可以通过扩展WebClient类来完成此操作

class ExtWebClient : WebClient
    {

        public NameValueCollection PostParam { get; set; }

        protected override WebRequest GetWebRequest(Uri address)
        {
            WebRequest tmprequest = base.GetWebRequest(address);

            HttpWebRequest request = tmprequest as HttpWebRequest;

            if (request != null && PostParam != null && PostParam.Count > 0)
            {
                StringBuilder postBuilder = new StringBuilder();
                request.Method = "POST";
                //build the post string

                for (int i = 0; i < PostParam.Count; i++)
                {
                    postBuilder.AppendFormat("{0}={1}", Uri.EscapeDataString(PostParam.GetKey(i)),
                                             Uri.EscapeDataString(PostParam.Get(i)));
                    if (i < PostParam.Count - 1)
                    {
                        postBuilder.Append("&");
                    }
                }
                byte[] postBytes = Encoding.ASCII.GetBytes(postBuilder.ToString());
                request.ContentLength = postBytes.Length;
                request.ContentType = "application/x-www-form-urlencoded";

                var stream = request.GetRequestStream();
                stream.Write(postBytes, 0, postBytes.Length);
                stream.Close();
                stream.Dispose();

            }

            return tmprequest;
        }
    }

用法:万一你必须创建POST类型请求

class Program
{
    private static void Main()
    {
        ExtWebClient webclient = new ExtWebClient();
        webclient.PostParam = new NameValueCollection();
        webclient.PostParam["param1"] = "value1";
        webclient.PostParam["param2"] = "value2";

        webclient.DownloadFile("http://www.example.com/myfile.zip", @"C:\myfile.zip");
    }
}

用法:对于GET类型请求,您可以简单地使用Normal webclient

class Program
{
    private static void Main()
    {
        WebClient webclient = new WebClient();

        webclient.DownloadFile("http://www.example.com/myfile.zip?param1=value1&param2=value2", @"C:\myfile.zip");
    }
}