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使用HttpClient增刪改查ASP.NET?Web?API服務_實用技巧

作者：Darren?Ji ? 更新時間： 2022-11-26 編程語言

本篇體驗使用HttpClient對ASP.NET Web API服務實現增刪改查。

創建ASP.NET Web API項目

新建項目，選擇"ASP.NET MVC 4 Web應用程序"。

選擇"Web API"。

在Models文件夾下創建Product類。

    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文件夾下創建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文件夾下創建ProductRepository類，實現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文件夾下創建空的ProductController。

   public class ProductController : ApiController
    {
        static readonly IProductRepository repository = new ProductRepository();
        //獲取所有
        public IEnumerable<Product> GetAllProducts()
        {
            return repository.GetAll();
        }
        //根據id獲取
        public Product GetProduct(int id)
        {
            Product item = repository.Get(id);
            if (item == null)
            {
                throw new HttpResponseException(HttpStatusCode.NotFound);
            }
            return item;
        }
        //根據類別查找所有產品
        public IEnumerable<Product> GetProductsByCategory(string category)
        {
            return
                repository.GetAll().Where(p => string.Equals(p.Category, category, StringComparison.OrdinalIgnoreCase));
        }
        //創建產品
        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;
        }
        //更新產品
        public void PutProduct(int id, Product product)
        {
            product.Id = id;
            if (!repository.Update(product))
            {
                throw new HttpResponseException(HttpStatusCode.NotFound);
            }
        }
        //刪除產品
        public void DeleteProduct(int id)
        {
            Product item = repository.Get(id);
            if (item == null)
            {
                throw new HttpResponseException(HttpStatusCode.NotFound);
            }
            repository.Remove(id);
        }
    }

在瀏覽器中輸入：

http://localhost:1310/api/Product?? 獲取到所有產品
http://localhost:1310/api/Product/1?? 獲取編號為1的產品

使用HttpClient查詢某個產品

在同一個解決方案下創建一個控制臺程序。

依次點擊"工具"，"庫程序包管理器","程序包管理器控制臺"，輸入如下：

Install-Package Microsoft.AspNet.WebApi.Client

在控制臺程序下添加Product類，與ASP.NET Web API中的對應。

    public class Product
    {
        public string Name { get; set; }
        public double Price { get; set; }
        public string Category { get; set; } 
    }

編寫如下：

        static void Main(string[] args)
        {
            RunAsync().Wait();
            Console.ReadKey();
        }
        static async Task RunAsync()
        {
            using (var client = new HttpClient())
            {
                //設置
                client.BaseAddress = new Uri("http://localhost:1310/");
                client.DefaultRequestHeaders.Accept.Clear();
                client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
                //異步獲取數據
                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);
                }
            }
        }

把控制臺項目設置為啟動項目。

HttpResponseMessage的IsSuccessStatusCode只能返回true或false，如果想讓響應拋出異常，需要使用EnsureSuccessStatusCode方法。

try
{
    HttpResponseMessage response = await client.GetAsync("/api/Product/1");
    response.EnsureSuccessStatusCode();//此方法確保響應失敗拋出異常
}
catch(HttpRequestException ex)
{
    //處理異常
}

另外，ReadAsAsync方法，默認接收MediaTypeFormatter類型的參數，支持 JSON, XML, 和Form-url-encoded格式，如果想自定義MediaTypeFormatter格式，參照如下：

var formatters = new List<MediaTypeFormatter>() {
    new MyCustomFormatter(),
    new JsonMediaTypeFormatter(),
    new XmlMediaTypeFormatter()
};
resp.Content.ReadAsAsync<IEnumerable<Product>>(formatters);

使用HttpClient查詢所有產品

       static void Main(string[] args)
        {
            RunAsync().Wait();
            Console.ReadKey();
        }
        static async Task RunAsync()
        {
            using (var client = new HttpClient())
            {
                //設置
                client.BaseAddress = new Uri("http://localhost:1310/");
                client.DefaultRequestHeaders.Accept.Clear();
                client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
                //異步獲取數據
                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())
            {
                //設置
                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);
                //異步獲取數據
                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())
            {
                //設置
                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);
                }
                //異步獲取數據
                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刪除

        static void Main(string[] args)
        {
            RunAsync().Wait();
            Console.ReadKey();
        }
        static async Task RunAsync()
        {
            using (var client = new HttpClient())
            {
                //設置
                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);
                    //刪除 HTTP DELETE
                    response = await client.DeleteAsync(pUrl);
                }
                //異步獲取數據
                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);
                    }
                    
                }
            }
        }

原文鏈接：https://www.cnblogs.com/darrenji/p/4437680.html

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