Asp.Net Core 5.0注册HttpClient时如何注入ILogger记录失败请求体

1. ILogger注入报错修复 #

报错 Unable to resolve service for type 'Microsoft.Extensions.Logging.ILogger' 的根本原因是：ASP.NET Core 依赖注入容器默认仅注册了泛型版本的ILogger<TCategoryName>，未注册非泛型的ILogger，你只需要将SomeHttpClient构造函数中的参数类型替换为泛型版本即可：

public class SomeHttpClient : ISomeHttpClient
{
    private readonly HttpClient _httpClient;
    private readonly ILogger<SomeHttpClient> _logger;

    // 修改构造函数的ILogger为泛型ILogger<SomeHttpClient>
    public SomeHttpClient(HttpClient httpClient, ILogger<SomeHttpClient> logger)
    {
        _httpClient = httpClient;
        _logger = logger;
    }

    // 业务方法省略
}

修改后即可正常注入日志组件，不会再报服务解析错误。

2. 非成功状态码请求体记录实现 #

推荐使用DelegatingHandler（请求委托处理器）实现该需求，该方案可以无侵入拦截HttpClient的所有请求响应流程，逻辑可复用，不需要修改业务代码：

步骤1：自定义请求拦截处理器 #

public class LogFailedRequestHandler : DelegatingHandler
{
    private readonly ILogger<LogFailedRequestHandler> _logger;

    public LogFailedRequestHandler(ILogger<LogFailedRequestHandler> logger)
    {
        _logger = logger;
    }

    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        // 启用请求体缓冲，避免读取后业务侧无法再次获取请求体
        if (request.Content != null)
        {
            await request.Content.LoadIntoBufferAsync();
        }

        // 执行后续请求流程
        var response = await base.SendAsync(request, cancellationToken);

        // 状态码非2xx时记录请求体
        if (!response.IsSuccessStatusCode && request.Content != null)
        {
            string requestBody = await request.Content.ReadAsStringAsync(cancellationToken);
            _logger.LogError("HTTP请求失败: 地址={RequestUrl}, 方法={Method}, 状态码={StatusCode}, 请求体={RequestBody}",
                request.RequestUri, request.Method, response.StatusCode, requestBody);
        }

        return response;
    }
}

步骤2：注册处理器到自定义HttpClient #

修改原服务注册代码，添加处理器的注册和绑定：

// 注册自定义请求处理器
services.AddTransient<LogFailedRequestHandler>();

services.AddHttpClient<ISomeHttpClient, SomeHttpClient>(client =>
{
    client.BaseAddress = new Uri(Configuration["Url"]);
    client.DefaultRequestHeaders.Add("Accept", "application/json");
})
// 绑定自定义处理器，拦截该HttpClient的所有请求
.AddHttpMessageHandler<LogFailedRequestHandler>();

如果你只需要给单个HttpClient临时加日志逻辑，也可以直接在SomeHttpClient的业务请求方法中，拿到HttpResponseMessage后判断IsSuccessStatusCode属性，手动读取请求体记录日志即可。

内容的提问来源于stack exchange，提问作者osotorrio