使用 PCL Xamarin Forms 将图像上传到 FTP 服务器

Question

我是 Xamarin 和 C# 世界的新手，我正在尝试将图像上传到 FTP 服务器。我看到 FtpWebRequest class 可以做到这一点，但我没有做对，我不知道如何注入特定于平台的代码，我什至不知道它的真正含义，已经看过这个视频（https://www.youtube.com/watch?feature=player_embedded&v=yduxdUCKU1c) 但我不知道如何使用它来创建 FtpWebRequest class 并上传图像。

我看到这个代码（这里：https://forums.xamarin.com/discussion/9052/strange-behaviour-with-ftp-upload）发送图片，但我无法使用它。

public void sendAPicture(string picture)
{

    string ftpHost = "xxxx";

    string ftpUser = "yyyy";

    string ftpPassword = "zzzzz";

    string ftpfullpath = "ftp://myserver.com/testme123.jpg";

    FtpWebRequest ftp = (FtpWebRequest)FtpWebRequest.Create(ftpfullpath);

    //userid and password for the ftp server  

    ftp.Credentials = new NetworkCredential(ftpUser, ftpPassword);

    ftp.KeepAlive = true;
    ftp.UseBinary = true;
    ftp.Method = WebRequestMethods.Ftp.UploadFile;

    FileStream fs = File.OpenRead(picture);

    byte[] buffer = new byte[fs.Length];
    fs.Read(buffer, 0, buffer.Length);

    fs.Close();

    Stream ftpstream = ftp.GetRequestStream();
    ftpstream.Write(buffer, 0, buffer.Length);
    ftpstream.Close();
    ftpstream.Flush();

    //  fs.Flush();

}

我没有 FileStream、WebRequestMethods 和 File 类型，我的 FtpWebRequest class 也没有 "KeepAlive"、"UseBinary" 和 "GetRequestStream" 方法，并且我的 Stream class 没有 "Close" 方法。

我的 FtpWebRequest Class:

public 密封 class FtpWebRequest : WebRequest { public 覆盖字符串内容类型 { 得到 { 抛出新的 NotImplementedException()； }

    set
    {
        throw new NotImplementedException();
    }
}

public override WebHeaderCollection Headers
{
    get
    {
        throw new NotImplementedException();
    }

    set
    {
        throw new NotImplementedException();
    }
}

public override string Method
{
    get
    {
        throw new NotImplementedException();
    }

    set
    {
        throw new NotImplementedException();
    }
}

public override Uri RequestUri
{
    get
    {
        throw new NotImplementedException();
    }
}

public override void Abort()
{
    throw new NotImplementedException();
}

public override IAsyncResult BeginGetRequestStream(AsyncCallback callback, object state)
{
    throw new NotImplementedException();
}

public override IAsyncResult BeginGetResponse(AsyncCallback callback, object state)
{
    throw new NotImplementedException();
}

public override Stream EndGetRequestStream(IAsyncResult asyncResult)
{
    throw new NotImplementedException();
}

public override WebResponse EndGetResponse(IAsyncResult asyncResult)
{
    throw new NotImplementedException();
}

}

（我知道，我没有在那里写任何东西，只是按了 ctrl + 。因为我不知道在那里写什么）

谁能给我提供完整的 FtpWebRequest 示例 class？我只发现 class 像上面这样使用。

Answer 1

好的，我刚刚想出了如何做到这一点，我会展示我是怎么做的，我真的不知道这是否是更好和正确的方法，但它有效。

首先，我必须在我的表单项目上创建一个名为 IFtpWebRequest 的接口Class，它包含以下内容：

namespace Contato_Vistoria
{
        public interface IFtpWebRequest
        {
            string upload(string FtpUrl, string fileName, string userName, string password, string UploadDirectory = "");
        }
}

然后，在我的 iOS/droid 项目中，我必须创建一个 class caled FTP 来实现 IFtpWebRequest 并在那个 class 中编写上传函数（我'我现在正在使用另一个），这是整个 FTP class:

using System;
using System.IO;
using System.Net;
using Contato_Vistoria.Droid; //My droid project

[assembly: Xamarin.Forms.Dependency(typeof(FTP))] //You need to put this on iOS/droid class or uwp/etc if you wrote
namespace Contato_Vistoria.Droid
{
    class FTP : IFtpWebRequest
    {
        public FTP() //I saw on Xamarin documentation that it's important to NOT pass any parameter on that constructor
        {
        }

        /// Upload File to Specified FTP Url with username and password and Upload Directory if need to upload in sub folders
        ///Base FtpUrl of FTP Server
        ///Local Filename to Upload
        ///Username of FTP Server
        ///Password of FTP Server
        ///[Optional]Specify sub Folder if any
        /// Status String from Server
        public string upload(string FtpUrl, string fileName, string userName, string password, string UploadDirectory = "")
        {
            try
            {

                string PureFileName = new FileInfo(fileName).Name;
                String uploadUrl = String.Format("{0}{1}/{2}", FtpUrl, UploadDirectory, PureFileName);
                FtpWebRequest req = (FtpWebRequest)FtpWebRequest.Create(uploadUrl);
                req.Proxy = null;
                req.Method = WebRequestMethods.Ftp.UploadFile;
                req.Credentials = new NetworkCredential(userName, password);
                req.UseBinary = true;
                req.UsePassive = true;
                byte[] data = File.ReadAllBytes(fileName);
                req.ContentLength = data.Length;
                Stream stream = req.GetRequestStream();
                stream.Write(data, 0, data.Length);
                stream.Close();
                FtpWebResponse res = (FtpWebResponse)req.GetResponse();
                return res.StatusDescription;

            }
            catch(Exception err)
            {
                return err.ToString();
            }
        }
    }
}

它与我的 iOS 项目几乎相同，但我还是会 post 帮助那些像我这样不太了解并且需要查看完整示例的人去做吧。这是：

using System;
using System.Net;
using System.IO;
//Only thing that changes to droid class is that \/
using Foundation;
using UIKit;
using Contato_Vistoria.iOS;


[assembly: Xamarin.Forms.Dependency(typeof(FTP))]
namespace Contato_Vistoria.iOS  //   /\
{
    class FTP : IFtpWebRequest
    {
        public FTP()
        {

        }

        /// Upload File to Specified FTP Url with username and password and Upload Directory if need to upload in sub folders
        ///Base FtpUrl of FTP Server
        ///Local Filename to Upload
        ///Username of FTP Server
        ///Password of FTP Server
        ///[Optional]Specify sub Folder if any
        /// Status String from Server
        public string upload(string FtpUrl, string fileName, string userName, string password, string UploadDirectory = "")
        {
            try
            {
                string PureFileName = new FileInfo(fileName).Name;
                String uploadUrl = String.Format("{0}{1}/{2}", FtpUrl, UploadDirectory, PureFileName);
                FtpWebRequest req = (FtpWebRequest)FtpWebRequest.Create(uploadUrl);
                req.Proxy = null;
                req.Method = WebRequestMethods.Ftp.UploadFile;
                req.Credentials = new NetworkCredential(userName, password);
                req.UseBinary = true;
                req.UsePassive = true;
                byte[] data = File.ReadAllBytes(fileName);
                req.ContentLength = data.Length;
                Stream stream = req.GetRequestStream();
                stream.Write(data, 0, data.Length);
                stream.Close();
                FtpWebResponse res = (FtpWebResponse)req.GetResponse();
                return res.StatusDescription;

            }
            catch (Exception err)
            {
                return err.ToString();
            }
        }
    }
}

最后，回到我的 Xamarin Forms 项目，这就是我调用该函数的方式。在我的 GUI 上的按钮的简单点击事件中：

    protected async void btConcluidoClicked(object sender, EventArgs e)
    {
        if (Device.OS == TargetPlatform.Android || Device.OS == TargetPlatform.iOS)
            await DisplayAlert("Upload", DependencyService.Get<IFtpWebRequest>().upload("ftp://ftp.swfwmd.state.fl.us", ((ListCarImagesViewModel)BindingContext).Items[0].Image, "Anonymous", "gabriel@icloud.com", "/pub/incoming"), "Ok");

        await Navigation.PopAsync();
    }

要调用您需要编写的函数 "DependencyService.Get().YourFunction(Parameters of the function)"，更具体。

我就是这样做的，希望我能帮助到别人。

使用 PCL Xamarin Forms 将图像上传到 FTP 服务器

Upload image to a FTP Server using PCL Xamarin Forms

c#

ftp

xamarin.forms

image-uploading

ftpwebrequest