[HttpHost("http://www.webapiclient.com")] 
public interface IMyWebApi : IHttpApiClient
{
    // GET webapi/user?account=laojiu
    // Return 原始string内容
    [HttpGet("/webapi/user")]
    ITask<string> GetUserByAccountAsync(string account);

    // POST webapi/user  
    // Body Account=laojiu&password=123456
    // Return json或xml内容
    [HttpPost("/webapi/user")]
    ITask<UserInfo> UpdateUserWithFormAsync([FormContent] UserInfo user);
}

public class UserInfo
{
    public string Account { get; set; }

    [AliasAs("password")]
    public string Password { get; set; }

    [IgnoreSerialized]
    public string Email { get; set; }
}

static async Task TestAsync()
{
    var client = HttpApiClient.Create<IMyWebApi>();
    var user = new UserInfo { Account = "laojiu", Password = "123456" }; 
    var user1 = await client.GetUserByAccountAsync("laojiu");
    var user2 = await client.UpdateUserWithFormAsync(user);
}