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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