使用HttpClient增删改查ASP.NET Web API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){    returnrepository.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 POSTvar 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 POSTvar 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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