使用HttpClient增删改查ASP.NETWebAPI服务

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);                    }                                    }            }        }

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