Web API与文件操作

前段时间，一直有练习ASP.NET MVC与Web API交互，接下来，Insus.NET再做一些相关的练习，Web API与文件操作，如POST文件至Web API，更新或是删除等。

不管怎样，先在数据库创建一张表，用来存储上传的文件。本实例中是把文件存储过数据库的。

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

写到这里，发现少了一个存储过程，就是获取某一张图片的：

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

 
接下来，我们可以设计Web API接口，待完成了，发布至网上，其它客户端就可以操作了。

根据数据库表，可以在API项目中，创建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; }
    }
}

写好model之后，还需要为API写一个实体，这个对象只是让程序与数据库进行交互。获取与存储等操作：

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，即是为客户端访问的接口，这个类别，它是继承了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，我们需要把它发布至IIS中去，如何发布，可以参考《创建与使用Web API》http://www.cnblogs.com/insus/p/5019088.html......


Ok，接下来，我们开发客户端的程序，尝试上Web API上传一些文件。

在客户端的项目中，创建一个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，创建2个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");
        }

在视图中，可以这样做：

程序运行：

 图片上传成功之后，现在我们需要把图片显示出来。
由于存储的是二进制的数据流，显示图片时，需要处理一下，需要写一个自定义的Result，如：PictureResult，它需要继承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();
            }
        }
    }
}

接下来，我们在控制器创建视图的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;
        }

 
客户端程序运行，可以看到图片显示的效果：

在Web API的接口还有更新，删除的接口，看官们可以继续完成。方法在Insus.NET博客上也有相似或是相关的功能......