Web API與文件操作

前段時間，一直有練習ASP.NET MVC與Web API交互，接下來，Insus.NET再做一些相關的練習，Web API與文件操作，如POST文件至Web API，更新或是刪除等。

不管怎樣，先在數據庫創建一張表，用來存儲上傳的文件。本實例中是把文件存儲過數據庫的。

CREATE TABLE ApiFileDemo
(
    [Afd_nbr] INT IDENTITY(1,1) PRIMARY KEY NOT NULL,
    [Picture] [image] NULL,
    [PictureType] [nvarchar](30) NULL,
    [FileExtension] [nvarchar](10) NULL
)
GO

CREATE PROCEDURE [dbo].[usp_ApiFileDemo_Insert]
(    
    @Picture IMAGE,
    @PictureType NVARCHAR(30),
    @FileExtension NVARCHAR(10)
)
AS
INSERT INTO [dbo].[ApiFileDemo] ([Picture],[PictureType],[FileExtension]) VALUES (@Picture,@PictureType,@FileExtension)
GO

CREATE PROCEDURE [dbo].[usp_ApiFileDemo_Update]
(
    @Afd_nbr INT,
    @Picture IMAGE,
    @PictureType NVARCHAR(30),
    @FileExtension NVARCHAR(10)
)
AS
UPDATE [dbo].[ApiFileDemo]  SET [Picture] = @Picture,[PictureType] = @PictureType,[FileExtension] = @FileExtension WHERE [Afd_nbr] = @Afd_nbr
GO

CREATE PROCEDURE [dbo].[usp_ApiFileDemo_Delte]
(
    @Afd_nbr INT
)
AS
DELETE FROM [dbo].[ApiFileDemo] WHERE [Afd_nbr] = @Afd_nbr
GO

寫到這里，發現少了一個存儲過程，就是獲取某一張圖片的：

CREATE PROCEDURE [dbo].[usp_ApiFileDemo_GetByPrimarykey]
(
    @Afd_nbr INT
)
AS
SELECT [Afd_nbr],[Picture],[PictureType],[FileExtension] FROM [dbo].[ApiFileDemo] WHERE [Afd_nbr] = @Afd_nbr
GO

 
接下來，我們可以設計Web API接口，待完成了，發布至網上，其它客戶端就可以操作了。

根據數據庫表，可以在API項目中，創建Model:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Insus.NET.Models
{
    public class File
    {
        public int Afd_nbr { get; set; }

        public byte[] Picture { get; set; }

        public string PictureType { get; set; }

        public string FileExtension { get; set; }
    }
}

寫好model之后，還需要為API寫一個實體，這個對象只是讓程序與數據庫進行交互。獲取與存儲等操作：

using Insus.NET.DataBases;
using Insus.NET.Models;
using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Insus.NET;

namespace Insus.NET.Entities
{
    public class FileEntity
    {
        BizSP sp = new BizSP();
        public DataTable GetFileByPrimarykey(File f)
        {
            List<Parameter> param = new List<Parameter>() {
                                    new Parameter("@Afd_nbr", SqlDbType.Int,4,f.Afd_nbr)
            };
            sp.ConnectionString = DB.ConnectionString;
            sp.Parameters = param;
            sp.ProcedureName = "usp_ApiFileDemo_GetByPrimarykey";
            return sp.ExecuteDataSet().Tables[0];
        }

        public void Insert(File f)
        {
            List<Parameter> param = new List<Parameter>() {
                                    new Parameter("@Picture", SqlDbType.Image,-1,f.Picture),
                                    new Parameter("@PictureType",SqlDbType.NVarChar,-1,f.PictureType),
                                    new Parameter("@FileExtension",SqlDbType.NVarChar,-1,f.FileExtension)
            };
            sp.ConnectionString = DB.ConnectionString;
            sp.Parameters = param;
            sp.ProcedureName = "usp_ApiFileDemo_Insert";
            sp.Execute();
        }

        public void Update(File f)
        {
            List<Parameter> param = new List<Parameter>() {
                                    new Parameter("@Afd_nbr", SqlDbType.Int,4,f.Afd_nbr),
                                    new Parameter("@Picture", SqlDbType.Image,-1,f.Picture),
                                    new Parameter("@PictureType",SqlDbType.NVarChar,-1,f.PictureType),
                                    new Parameter("@FileExtension",SqlDbType.NVarChar,-1,f.FileExtension)
            };
            sp.ConnectionString = DB.ConnectionString;
            sp.Parameters = param;
            sp.ProcedureName = "usp_ApiFileDemo_Update";
            sp.Execute();
        }

        public void Delete(File f)
        {
            List<Parameter> param = new List<Parameter>() {
                                    new Parameter("@Afd_nbr", SqlDbType.Int,4,f.Afd_nbr)
            };
            sp.ConnectionString = DB.ConnectionString;
            sp.Parameters = param;
            sp.ProcedureName = "usp_ApiFileDemo_Delte";
            sp.Execute();
        }
    }
}

 

下面的控制器FileController，即是為客戶端訪問的接口，這個類別，它是繼承了ApiController。

 

using Insus.NET.Entities;
using Insus.NET.ExtendMethods;
using Insus.NET.Models;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;

namespace Insus.NET.Controllers
{
    public class FileController : ApiController
    {
        // GET: File
        FileEntity fe = new FileEntity();

        // GET: ApiFileDemo

        [HttpGet]
        public string Get(int id)
        {
            File f = new File();
            f.Afd_nbr = id;
            return fe.GetFileByPrimarykey(f).ToJson();
        }

        [HttpPost]
        public void Post(File f)
        {
            fe.Insert(f);
        }

        [HttpPut]
        public void Put(File f)
        {
            fe.Update(f);
        }

        [HttpDelete]
        public void Delete(File f)
        {
            fe.Delete(f);
        }

        [HttpDelete]
        public void Delete(int id)
        {
            File f = new File();
            f.Afd_nbr = id;
            fe.Delete(f);
        }
    }
}

 
Web API完成，我們需要把它發布至IIS中去，如何發布，可以參考《創建與使用Web API》http://www.cnblogs.com/insus/p/5019088.html......


Ok，接下來，我們開發客戶端的程序，嘗試上Web API上傳一些文件。

在客戶端的項目中，創建一個mode:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Insus.NET.Models
{
    public class File
    {
        public int Afd_nbr { get; set; }

        public byte[] Picture { get; set; }

        public string PictureType { get; set; }

        public string FileExtension { get; set; }
    }
}

 

ASP.NET MVC的控制器中，創建2個Action:

 

 public ActionResult Upload()
        {
            return View();
        }

        [HttpPost]
        public ActionResult Upload(IEnumerable<HttpPostedFileBase> files)
        {
            foreach (var file in files)
            {
                if (file.ContentLength > 0)
                {
                    Insus.NET.Models.File f = new Insus.NET.Models.File();
                    f.PictureType = file.ContentType;
                    string fn = Path.GetFileName(file.FileName);
                    f.FileExtension = fn.Substring(fn.LastIndexOf('.'));
                    using (Stream inputStream = file.InputStream)
                    {
                        MemoryStream memoryStream = inputStream as MemoryStream;
                        if (memoryStream == null)
                        {
                            memoryStream = new MemoryStream();
                            inputStream.CopyTo(memoryStream);
                        }
                        f.Picture = memoryStream.ToArray();
                    }
                    HttpClient client = new HttpClient();
                    string ff = f.ToJson();
                    HttpContent httpcontent = new StringContent(ff, System.Text.Encoding.UTF8, "application/json");
                    client.PostAsync("http://localhost:9001/api/file", httpcontent)
                        .ContinueWith((postTask) =>
                        {
                            postTask.Result.EnsureSuccessStatusCode();
                        });
                }
            }
            return RedirectToAction("Upload");
        }

 

在視圖中，可以這樣做：

 

程序運行：

 

 圖片上傳成功之后，現在我們需要把圖片顯示出來。
由於存儲的是二進制的數據流，顯示圖片時，需要處理一下，需要寫一個自定義的Result，如：PictureResult，它需要繼承ContentResult：

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Web;
using System.Web.Mvc;

namespace Insus.NET.Results
{
    public class PictureResult : ContentResult
    {
        public byte[] _Picture { get; set; }
        public string _PictureType { get; set; }

        public PictureResult(byte[] sourceStream, String contentType)
        {
            _Picture = sourceStream;
            _PictureType = contentType;
        }

        public override void ExecuteResult(ControllerContext context)
        {
            var response = context.HttpContext.Response;
            response.Clear();
            response.Cache.SetCacheability(HttpCacheability.NoCache);
            response.ContentType = ContentType;

            if (_Picture != null)
            {
                var stream = new MemoryStream(_Picture);
                stream.WriteTo(response.OutputStream);
                stream.Dispose();
            }
        }
    }
}

接下來，我們在控制器創建視圖的Action:

 

 public ActionResult ShowPhoto()
        {
            return View();
        }
        
        public ActionResult ShowPicture(int id)
        {
            var files = ApiUtility.Get<Insus.NET.Models.File>("http://localhost:9001/api/file/" + id);
            var model = files.FirstOrDefault();

            PictureResult pictureResult = new PictureResult(model.Picture, model.PictureType);
            return pictureResult;
        }

 
客戶端程序運行，可以看到圖片顯示的效果：

在Web API的接口還有更新，刪除的接口，看官們可以繼續完成。方法在Insus.NET博客上也有相似或是相關的功能......