使用HttpClient对ASP.NET Web API服务实现增删改查

本篇体验使用HttpClient对ASP.NET Web API服务实现增删改查。

创建ASP.NET Web API项目

新建项目，选择"ASP.NET MVC 4 Web应用程序"。

选择"Web API"。

在Models文件夹下创建Product类。

    public class Product

    {

        public int Id { get; set; }

        public string Name { get; set; }

        public string Category { get; set; }

        public decimal Price { get; set; }

    }

在Models文件夹下创建IProductRepository接口。

    public interface IProductRepository

    {

        IEnumerable<Product> GetAll();

        Product Get(int id);

        Product Add(Product item);

        void Remove(int id);

        bool Update(Product item);

    }

在Models文件夹下创建ProductRepository类，实现IProductRepository接口。

   public class ProductRepository : IProductRepository

    {

        private List<Product> products = new List<Product>();

        private int _nextId = 1;


        public ProductRepository()

        {

            Add(new Product() {Name = "product1", Category = "sports", Price = 88M});

            Add(new Product() { Name = "product2", Category = "sports", Price = 98M });

            Add(new Product() { Name = "product3", Category = "toys", Price = 58M });

        }


        public IEnumerable<Product> GetAll()

        {

            return products;

        }


        public Product Get(int id)

        {

            return products.Find(p => p.Id == id);

        }


        public Product Add(Product item)

        {

            if (item == null)

            {

                throw new ArgumentNullException("item");

            }

            item.Id = _nextId++;

            products.Add(item);

            return item;

        }


        public bool Update(Product item)

        {

            if (item == null)

            {

                throw new ArgumentNullException("item");

            }

            int index = products.FindIndex(p => p.Id == item.Id);

            if (index == -1)

            {

                return false;

            }

            products.RemoveAt(index);

            products.Add(item);

            return true;

        }


        public void Remove(int id)

        {

            products.RemoveAll(p => p.Id == id);

        }

    }

在Controllers文件夹下创建空的ProductController。

   public class ProductController : ApiController

    {

        static readonly IProductRepository repository = new ProductRepository();


        //获取所有

        public IEnumerable<Product> GetAllProducts()

        {

            return repository.GetAll();

        }


        //根据id获取

        public Product GetProduct(int id)

        {

            Product item = repository.Get(id);

            if (item == null)

            {

                throw new HttpResponseException(HttpStatusCode.NotFound);

            }

            return item;

        }


        //根据类别查找所有产品

        public IEnumerable<Product> GetProductsByCategory(string category)

        {

            return

                repository.GetAll().Where(p => string.Equals(p.Category, category, StringComparison.OrdinalIgnoreCase));

        }


        //创建产品

        public HttpResponseMessage PostProduct(Product item)

        {

            item = repository.Add(item);


            var response = Request.CreateResponse(HttpStatusCode.Created, item);

            string uri = Url.Link("DefaultApi", new {id = item.Id});

            response.Headers.Location = new Uri(uri);

            return response;

        }


        //更新产品

        public void PutProduct(int id, Product product)

        {

            product.Id = id;

            if (!repository.Update(product))

            {

                throw new HttpResponseException(HttpStatusCode.NotFound);

            }

        }


        //删除产品

        public void DeleteProduct(int id)

        {

            Product item = repository.Get(id);

            if (item == null)

            {

                throw new HttpResponseException(HttpStatusCode.NotFound);

            }

            repository.Remove(id);

        }

    }

在浏览器中输入：

http://localhost:1310/api/Product   获取到所有产品
http://localhost:1310/api/Product/1   获取编号为1的产品

使用HttpClient查询某个产品

在同一个解决方案下创建一个控制台程序。

依次点击"工具"，"库程序包管理器","程序包管理器控制台"，输入如下：

Install-Package Microsoft.AspNet.WebApi.Client

在控制台程序下添加Product类，与ASP.NET Web API中的对应。

    public class Product

    {

        public string Name { get; set; }

        public double Price { get; set; }

        public string Category { get; set; }

    }

编写如下：

        static void Main(string[] args)

        {

            RunAsync().Wait();

            Console.ReadKey();

        }


        static async Task RunAsync()

        {

            using (var client = new HttpClient())

            {

                //设置

                client.BaseAddress = new Uri("http://localhost:1310/");

                client.DefaultRequestHeaders.Accept.Clear();

                client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));


                //异步获取数据

                HttpResponseMessage response = await client.GetAsync("/api/Product/1");

                if (response.IsSuccessStatusCode)

                {

                    Product product = await response.Content.ReadAsAsync<Product>();

                    Console.WriteLine("{0}\t{1}元\t{2}",product.Name, product.Price, product.Category);

                }

            }

        }

把控制台项目设置为启动项目。

HttpResponseMessage的IsSuccessStatusCode只能返回true或false，如果想让响应抛出异常，需要使用EnsureSuccessStatusCode方法。

try

{

    HttpResponseMessage response = await client.GetAsync("/api/Product/1");

    response.EnsureSuccessStatusCode();//此方法确保响应失败抛出异常

}

catch(HttpRequestException ex)

{

    //处理异常

}

另外，ReadAsAsync方法，默认接收MediaTypeFormatter类型的参数，支持 JSON, XML, 和Form-url-encoded格式，如果想自定义MediaTypeFormatter格式，参照如下：

var formatters = new List<MediaTypeFormatter>() {

    new MyCustomFormatter(),

    new JsonMediaTypeFormatter(),

    new XmlMediaTypeFormatter()

};

resp.Content.ReadAsAsync<IEnumerable<Product>>(formatters);

使用HttpClient查询所有产品

       static void Main(string[] args)

        {

            RunAsync().Wait();

            Console.ReadKey();

        }


        static async Task RunAsync()

        {

            using (var client = new HttpClient())

            {

                //设置

                client.BaseAddress = new Uri("http://localhost:1310/");

                client.DefaultRequestHeaders.Accept.Clear();

                client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));


                //异步获取数据

                HttpResponseMessage response = await client.GetAsync("/api/Product");

                if (response.IsSuccessStatusCode)

                {

                    IEnumerable<Product> products = await response.Content.ReadAsAsync<IEnumerable<Product>>();

                    foreach (var item in products)

                    {

                        Console.WriteLine("{0}\t{1}元\t{2}", item.Name, item.Price, item.Category);

                    }


                }

            }

        }

使用HttpClient添加

       static void Main(string[] args)

        {

            RunAsync().Wait();

            Console.ReadKey();

        }


        static async Task RunAsync()

        {

            using (var client = new HttpClient())

            {

                //设置

                client.BaseAddress = new Uri("http://localhost:1310/");

                client.DefaultRequestHeaders.Accept.Clear();

                client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));


                //添加

                var myProduct = new Product() { Name = "myproduct", Price = 88, Category = "other" };

                HttpResponseMessage response = await client.PostAsJsonAsync("api/Product", myProduct);


                //异步获取数据

                response = await client.GetAsync("/api/Product");

                if (response.IsSuccessStatusCode)

                {

                    IEnumerable<Product> products = await response.Content.ReadAsAsync<IEnumerable<Product>>();

                    foreach (var item in products)

                    {

                        Console.WriteLine("{0}\t{1}元\t{2}", item.Name, item.Price, item.Category);

                    }


                }

            }

        }

使用HttpClient修改

       static void Main(string[] args)

        {

            RunAsync().Wait();

            Console.ReadKey();

        }


        static async Task RunAsync()

        {

            using (var client = new HttpClient())

            {

                //设置

                client.BaseAddress = new Uri("http://localhost:1310/");

                client.DefaultRequestHeaders.Accept.Clear();

                client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));


                //添加 HTTP POST

                var myProduct = new Product() { Name = "myproduct", Price = 100, Category = "other" };

                HttpResponseMessage response = await client.PostAsJsonAsync("api/product", myProduct);

                if (response.IsSuccessStatusCode)

                {

                    Uri pUrl = response.Headers.Location;


                    //修改 HTTP PUT

                    myProduct.Price = 80;   // Update price

                    response = await client.PutAsJsonAsync(pUrl, myProduct);

                }


                //异步获取数据

                response = await client.GetAsync("/api/Product");

                if (response.IsSuccessStatusCode)

                {

                    IEnumerable<Product> products = await response.Content.ReadAsAsync<IEnumerable<Product>>();

                    foreach (var item in products)

                    {

                        Console.WriteLine("{0}\t{1}元\t{2}", item.Name, item.Price, item.Category);

                    }


                }

            }

        }

使用HttpClient删除

        static void Main(string[] args)

        {

            RunAsync().Wait();

            Console.ReadKey();

        }


        static async Task RunAsync()

        {

            using (var client = new HttpClient())

            {

                //设置

                client.BaseAddress = new Uri("http://localhost:1310/");

                client.DefaultRequestHeaders.Accept.Clear();

                client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));


                //添加 HTTP POST

                var myProduct = new Product() { Name = "myproduct", Price = 100, Category = "other" };

                HttpResponseMessage response = await client.PostAsJsonAsync("api/product", myProduct);

                if (response.IsSuccessStatusCode)

                {

                    Uri pUrl = response.Headers.Location;


                    //修改 HTTP PUT

                    myProduct.Price = 80;   // Update price

                    response = await client.PutAsJsonAsync(pUrl, myProduct);


                    //删除 HTTP DELETE

                    response = await client.DeleteAsync(pUrl);

                }


                //异步获取数据

                response = await client.GetAsync("/api/Product");

                if (response.IsSuccessStatusCode)

                {

                    IEnumerable<Product> products = await response.Content.ReadAsAsync<IEnumerable<Product>>();

                    foreach (var item in products)

                    {

                        Console.WriteLine("{0}\t{1}元\t{2}", item.Name, item.Price, item.Category);

                    }


                }

            }

        }

完。