HttpWebRequest实现下载图片至本地

本文为大家分享了HttpWebRequest实现下载图片至本地的具体代码，供大家参考，具体内容如下

HttpWebRequest发送web请求，获取流文件，保存至本地

using System;
using System.IO;
using System.Net;
using System.Text;
using System.Web.Mvc;

namespace Web.Controllers
{
  public class HomeController : Controller
  {
    string url = "http://www.***.com/Image.aspx?ucode=ucode";

    public Stream GetFileToStream(string filePath)
    {
      FileStream fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read);
      byte[] bytes = new byte[fileStream.Length];
      fileStream.Read(bytes, 0, bytes.Length);
      fileStream.Close();
      Stream streamFile = new MemoryStream(bytes);
      return streamFile;
    }

    public void Method1()
    {
      string fileName = @"\upload\" + GenerateTimeStamp() + ".jpg";

      string webPath = Server.MapPath(fileName);
      string pathName = @"d:\" + GenerateTimeStamp() + ".jpg";
      HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);

      req.ServicePoint.Expect100Continue = false;
      req.Method = "GET";
      req.KeepAlive = true;

      req.ContentType = "image/png";
      HttpWebResponse rsp = (HttpWebResponse)req.GetResponse();

      System.IO.Stream stream = null;

      try
      {
        //以字符流的方式读取HTTP响应
        stream = rsp.GetResponseStream();
        System.Drawing.Image.FromStream(stream).Save(pathName);
      }
      finally
      {
        // 释放资源
        if (stream != null) stream.Close();
        if (rsp != null) rsp.Close();
      }
    }

    protected void Method2()
    {
      string fileName = @"\upload\" + GenerateTimeStamp() + ".jpg";

      string webPath = Server.MapPath(fileName);
      string pathName = @"d:\" + GenerateTimeStamp() + ".jpg";
      HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create(url);
      myRequest.Method = "GET";

      HttpWebResponse myResponse = null;
      try
      {
        myResponse = (HttpWebResponse)myRequest.GetResponse();
        StreamReader reader = new StreamReader(myResponse.GetResponseStream(), Encoding.UTF8);
        Stream stream = myResponse.GetResponseStream();

        #region 保存下载图片

        MemoryStream ms = null;
        Byte[] buffer = new Byte[myResponse.ContentLength];
        int offset = 0, actuallyRead = 0;
        do
        {
          actuallyRead = stream.Read(buffer, offset, buffer.Length - offset);
          offset += actuallyRead;
        }
        while (actuallyRead > 0);
        ms = new MemoryStream(buffer);

        byte[] buffurPic = ms.ToArray();
        System.IO.File.WriteAllBytes(pathName, buffurPic);

        #endregion
      }
      //异常请求
      catch (WebException ex)
      {

      }
    }

    protected void Method3()
    {
      string fileName = @"\upload\" + GenerateTimeStamp() + ".jpg";

      string webPath = Server.MapPath(fileName);
      string pathName = @"d:\" + GenerateTimeStamp() + ".jpg";
      HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create(url);
      myRequest.Method = "GET";

      HttpWebResponse myResponse = null;
      try
      {
        myResponse = (HttpWebResponse)myRequest.GetResponse();
        StreamReader reader = new StreamReader(myResponse.GetResponseStream(), Encoding.UTF8);
        Stream stream = myResponse.GetResponseStream();

        #region 保存下载图片

        FileStream fileStream = new FileStream(pathName, FileMode.Create, FileAccess.Write);
        byte[] bytes = new byte[1024];
        int readSize = 0;
        while ((readSize = stream.Read(bytes, 0, 1024)) > 0)
        {
          fileStream.Write(bytes, 0, readSize);
          fileStream.Flush();
        }
        #endregion

        myResponse.Close();
        stream.Close();
        fileStream.Close();
      }
      //异常请求
      catch (WebException ex)
      {

      }
      finally
      {

      }
    }

    public string GenerateTimeStamp()
    {
      TimeSpan ts = DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, 0);
      return Convert.ToInt64(ts.TotalMilliseconds).ToString();
    }
  }
}

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