How to call webApi

How to call webapi? How to call the webApi interface using a program?

In C#, there are generally two ways to call the HTTP interface:

1. WebRequest/WebResponse combined method call

2.WebClient class to call.

The first method is less abstract and more cumbersome to use; while WebClient is mainly oriented to WEB web page scenarios and is more convenient to use when simulating Web operations, but it is more troublesome to use in RestFul scenarios. In Web API At the time of release, .NET provides two assemblies: System.Net.Http and System.Net.Http.Formatting. The core class in these two assemblies is HttpClient.

These two assemblies are included in .NET4.5, and .NET4 needs to download the two packages Microsoft.Net.Http and Microsoft.AspNet.WebApi.Client from Nuget to use this class. Lower .NET versions can only express regret and can only use WebRequest/WebResponse or WebClient to call these APIs.

In use, the System.Net.Http assembly provides the HttpClient class and related HTTP calls, while System.Net.Http.Formatting provides some help extensions for HttpClient to better support Content negotiation, Content creation and other functions.

Let me write this example with you:

public class Person

    {

        public long Id { get; set; }        public string Name { get; set; } 

        public int Age { get; set; } 

        public string Sex { get; set; } 

        public override string ToString()

        {            return $"Id={Id} Name={Name} Age={Age} Sex={Sex}";

        }

    }

class Program
   {
       static void Main(string[] args)
       {
           var client = new HttpClient();
           //基本的API URL
           client.BaseAddress = new Uri("http://localhost:22658/");
           //默认希望响应使用Json序列化(内容协商机制，我接受json格式的数据)
           client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json")); 
           //运行client接收程序
           Run(client);
           Console.ReadLine();
       }
       //client接收处理（都是异步的处理）
       static async void Run(HttpClient client)
       {
           //post 请求插入数据
           var result = await AddPerson(client);
           Console.WriteLine($"添加结果：{result}"); //添加结果：true
           
           //get 获取数据
           var person = await GetPerson(client);
           //查询结果：Id=1 Name=test Age=10 Sex=F
           Console.WriteLine($"查询结果：{person}"); 
           //put 更新数据
           result = await PutPerson(client);
           //更新结果：true
           Console.WriteLine($"更新结果：{result}"); 
           //delete 删除数据
           result = await DeletePerson(client);
           //删除结果：true
           Console.WriteLine($"删除结果：{result}"); 
       }
       
       //post
       static async Task<bool> AddPerson(HttpClient client)
       {
           //向Person发送POST请求，Body使用Json进行序列化
           return await client.PostAsJsonAsync("api/Person", new Person() { Age = 10, Id = 1, Name = "test", Sex = "F" }) 
                               //返回请求是否执行成功，即HTTP Code是否为2XX
                               .ContinueWith(x => x.Result.IsSuccessStatusCode);  
       }
       
       //get
       static async Task<Person> GetPerson(HttpClient client)
       {
           //向Person发送GET请求
           return await await client.GetAsync("api/Person/1") 
           //获取返回Body，并根据返回的Content-Type自动匹配格式化器反序列化Body内容为对象
                                    .ContinueWith(x => x.Result.Content.ReadAsAsync<Person>(                             
                   new List<MediaTypeFormatter>() {new JsonMediaTypeFormatter()/*这是Json的格式化器*/
                                                   ,new XmlMediaTypeFormatter()/*这是XML的格式化器*/}));
       }
       
       //put
       static async Task<bool> PutPerson(HttpClient client)
       {
           //向Person发送PUT请求，Body使用Json进行序列化
           return await client.PutAsJsonAsync("api/Person/1", new Person() { Age = 10, Id = 1, Name = "test1Change", Sex = "F" }) 
                               .ContinueWith(x => x.Result.IsSuccessStatusCode);  //返回请求是否执行成功，即HTTP Code是否为2XX
       }
       //delete
       static async Task<bool> DeletePerson(HttpClient client)
       {
           return await client.DeleteAsync("api/Person/1") //向Person发送DELETE请求
                              .ContinueWith(x => x.Result.IsSuccessStatusCode); //返回请求是否执行成功，即HTTP Code是否为2XX
       }
}

This completes the call to this set of APIs. Isn’t it very simple and convenient? HTTPClient uses a fully asynchronous method and has good scalability.

OK, so far a set of simple Restful API and C# client calls have been completed, but this is just the beginning. Web API is a very powerful framework, and its extension points are very rich. These extensions It can provide a lot of help for our development.

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