C# RESTful完整使用实战示例

// 1. 获取数据 - HttpClient最佳实践
using var httpClient = new HttpClient();
var response = await httpClient.GetAsync("https://api.example.com/data");
var jsonString = await response.Content.ReadAsStringAsync();
// 2. 解析JSON - 两种常用方式
// 方式一：动态解析（快速提取少量字段）
var jsonDoc = JsonDocument.Parse(jsonString);
string name = jsonDoc.RootElement.GetProperty("user").GetProperty("name").GetString();
// 方式二：强类型解析（推荐！）
public class User {
    public string Name { get; set; }
    public int Age { get; set; }
    public DateTime RegisterDate { get; set; }
}
var user = JsonSerializer.Deserialize<User>(jsonString, new JsonSerializerOptions {
    PropertyNameCaseInsensitive = true // 忽略大小写
});
// 3. 使用解析后的数据
Console.WriteLine($"欢迎，{user.Name}！您已注册于{user.RegisterDate:yyyy-MM-dd}");

using System;
using System.Net.Http;
using System.Text.Json;
using System.Threading.Tasks;
public class WeatherApiService
{
    public async Task<WeatherData> GetWeatherAsync(string location)
    {
        using var httpClient = new HttpClient();
        // 获取天气数据
        var response = await httpClient.GetAsync(
            $"https://api.weather.com/v3?location={location}");
        response.EnsureSuccessStatusCode();
        var json = await response.Content.ReadAsStringAsync();
        // 强类型解析（推荐方式）
        return JsonSerializer.Deserialize<WeatherData>(json, new JsonSerializerOptions {
            PropertyNameCaseInsensitive = true,
            NumberHandling = JsonNumberHandling.AllowReadingFromString
        });
    }
}
public class WeatherData
{
    public string City { get; set; }
    public string Condition { get; set; }
    public int Temperature { get; set; }
    public DateTime ForecastDate { get; set; }
}

// 定义嵌套结构
public class ApiResponse
{
    public string Status { get; set; }
    public Data Data { get; set; }
}
public class Data
{
    public List<User> Users { get; set; }
    public Meta Meta { get; set; }
}
public class User
{
    public int Id { get; set; }
    public string Name { get; set; }
    public Address Address { get; set; }
}
public class Address
{
    public string Street { get; set; }
    public string City { get; set; }
    public string ZipCode { get; set; }
}
public class Meta
{
    public int TotalCount { get; set; }
    public int Page { get; set; }
    public int PageSize { get; set; }
}

// 获取API返回的JSON字符串
string json = await httpClient.GetStringAsync("https://api.example.com/data");
// 一行代码解析嵌套结构（这才是真正的"快速"！）
var response = JsonSerializer.Deserialize<ApiResponse>(json, new JsonSerializerOptions
{
    PropertyNameCaseInsensitive = true, // 忽略大小写
    NumberHandling = JsonNumberHandling.AllowReadingFromString // 处理数字字符串
});

// 安全访问嵌套数据
if (response != null && response.Data != null && response.Data.Users != null)
{
    foreach (var user in response.Data.Users)
    {
        Console.WriteLine($"用户: {user.Name}, 城市: {user.Address.City}");
    }
    // 也可以直接访问
    Console.WriteLine($"总用户数: {response.Data.Meta.TotalCount}");
}

// 安全访问嵌套字段（避免NullReferenceException）
var city = response?.Data?.Users?[0]?.Address?.City ?? "N/A";
Console.WriteLine($"城市: {city}");

new JsonSerializerOptions
{
    PropertyNameCaseInsensitive = true // 关键！忽略大小写
}

// 忽略未知字段
new JsonSerializerOptions
{
    IgnoreUnknown = true
}

// 获取所有用户的姓名
var userNames = response.Data.Users
    .Where(u => u.Id > 100)
    .Select(u => u.Name)
    .ToList();

public class WeatherResponse
{
    public CurrentWeather Current { get; set; }
    public Forecast Forecast { get; set; }
}
public class CurrentWeather
{
    public string City { get; set; }
    public int Temperature { get; set; }
    public string Condition { get; set; }
}
public class Forecast
{
    public List<DailyForecast> Days { get; set; }
}
public class DailyForecast
{
    public DateTime Date { get; set; }
    public int HighTemp { get; set; }
    public int LowTemp { get; set; }
}
// 使用方式
var weather = JsonSerializer.Deserialize<WeatherResponse>(json);
Console.WriteLine($"当前城市: {weather.Current.City}, 温度: {weather.Current.Temperature}°C");
Console.WriteLine($"明天最高温: {weather.Forecast.Days[0].HighTemp}°C");