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();
    }
  }
}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。