WebApi 统一封装返回结果+全局异常处理

郑子铭

发布于 2023-12-26 19:07:26

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代码可运行

文章被收录于专栏：DotNet NB && CloudNativeDotNet NB && CloudNative

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代码可运行

统一封装返回结果

使用一个枚举类封装一下常用的业务代码

public enum ResultCode
{
    [Description("操作失败！")]
    Fail = 10000,
    [Description("请求成功！")]
    Success = 20000
}

我又想要能够在返回状态码的时候能够附带着返回一下对应的Descrioption，所以定义一个静态类，用于获取enum类上的Description特性

public static class EnumHelper
{
    // 获取枚举类型的所有值和它们的描述
    public static Dictionary<T, string> GetDescriptions<T>() where T : Enum
    {
        var descriptions = new Dictionary<T, string>();

        foreach (var value in Enum.GetValues(typeof(T)).Cast<T>())
        {
            var fieldInfo = typeof(T).GetField(value.ToString());
            var attributes = (DescriptionAttribute[])fieldInfo.GetCustomAttributes(
                typeof(DescriptionAttribute), false);
            descriptions[value] = attributes.Length > 0 ? attributes[0].Description : value.ToString();
        }

        return descriptions;
    }
}

现在来定义要返回的JsonResult类

public class JsonResult
{
    public bool Success { get; set; }
    public int Code { get; set; }
    public string? Msg { get; set; }
    public Object? Data { get; set; }

    public JsonResult(){}
    public JsonResult(bool success)
    {
        Success = success;
        Code = success ? (int)ResultCode.Success : (int)ResultCode.Fail;
        Msg = ResultTool.DescriptionsDictionary[(ResultCode)Code];
    }

    
    public JsonResult(bool success, string msg)
    {
        Success = success;
        Code = success ? (int)ResultCode.Success : (int)ResultCode.Fail;
        Msg = msg;
    }

    public JsonResult(bool success, ResultCode resultEnum)
    {
        Success = success;
        Code = success ? (int)ResultCode.Success : (int)resultEnum;
        Msg = ResultTool.DescriptionsDictionary[(ResultCode)Code];
    }

    public JsonResult(bool success, Object data)
    {
        Success = success;
        Code = success ? (int)ResultCode.Success : (int)ResultCode.Fail;
        Msg = ResultTool.DescriptionsDictionary[(ResultCode)Code];
        Data = data;
    }

    public JsonResult(bool success, ResultCode resultEnum, Object data)
    {
        Success = success;
        Code = success ? (int)ResultCode.Success : (int)resultEnum;
        Msg = ResultTool.DescriptionsDictionary[(ResultCode)Code];
        Data = data;
    }

    public JsonResult(bool success, ResultCode resultEnum, string msg)
    {
        Success = success;
        Code = success ? (int)ResultCode.Success : (int)resultEnum;
        this.Msg = msg;
    }
    
}

使用ResultTool快速构建一个JsonResult类

public static class ResultTool
{
    public static Dictionary<ResultCode, string> DescriptionsDictionary = EnumHelper.GetDescriptions<ResultCode>();
    
    
    public static JsonResult Success()
    {
        return new JsonResult(true);
    }

    public static JsonResult Success(Object data)
    {
        return new JsonResult(true, data);
    }

    public static JsonResult Fail()
    {
        return new JsonResult(false);
    }

    public static JsonResult Fail(ResultCode resultCode)
    {
        return new JsonResult(false, resultCode);
    }

    public static JsonResult Fail(ResultCode resultCode, string msg)
    {
        return new JsonResult(false, resultCode, msg);
    }

    public static JsonResult Fail(string msg)
    {
        return new JsonResult(false, msg);
    }

    public static JsonResult Fail(bool b, ResultCode resultCode, string message)
    {
        return new JsonResult(false, resultCode, message);
    }
}

现在去Controlle中尝试下

[ApiController]
[Route("[controller]")]
public class WeatherForecastController : ControllerBase
{
    private static readonly string[] Summaries = new[]
    {
        "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
    };

    private readonly ILogger<WeatherForecastController> _logger;

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

    [HttpGet(Name = "GetWeatherForecast")]
    public JsonResult Get()
    {
        var MyList = Enumerable.Range(1, 2).Select(index => new WeatherForecast
            {
                Date = DateTime.Now.AddDays(index),
                TemperatureC = Random.Shared.Next(-20, 55),
                Summary = Summaries[Random.Shared.Next(Summaries.Length)]
            })
            .ToArray();
        return ResultTool.Success(MyList);
    }
}

现在能够正确的返回我想要的格式。有很多大佬使用了中间件或者过滤器来实现统一封装返回结果，我个人感觉我这种方式比较简单，也比较便于理解。

全局异常处理

程序运行时难免出现异常情况，有时候是我们手动抛出业务异常返回给前端，比如删除的字段前端没有传给我们导致的异常。我们手动抛出一个异常试一下。

尝试对异常进行处理，也能够返回对应的JsonResult。首先定义一个BusinessException继承Exception。

public class BusinessException : Exception
{
    public ResultCode ErrorCode { get; set; }

    public BusinessException(string message) : base(message)
    {
        ErrorCode = ResultCode.Fail;
    }

    public BusinessException(ResultCode errorCode, string message) : base(message)
    {
        this.ErrorCode = errorCode;
    }
}

然后定义一个中间件，以便捕获程序运行中的异常。

public class ExceptionHandlerMiddleware
{
    private readonly RequestDelegate _next;

    public ExceptionHandlerMiddleware(RequestDelegate next)
    {
        _next = next;
    }

    public async Task Invoke(HttpContext context)
    {
        try
        {
            await _next(context);
        }
        catch (Exception ex)
        {
            await HandleExceptionAsync(context, ex);
        }
    }

    private static Task HandleExceptionAsync(HttpContext context, Exception exception)
    {
        context.Response.ContentType = "application/json";
        context.Response.StatusCode = (int)HttpStatusCode.OK;

        JsonResult result;

        if (exception is BusinessException businessException)
        {
            // BusinessException处理
            result = ResultTool.Fail(businessException.ErrorCode, businessException.Message);
        }
        else
        {
            // 其他未处理异常处理
            // result = ResultTool.Fail(ResultCode.Fail, exception.Message);
            result = ResultTool.Fail(ResultCode.Fail, "系统异常！");
        }

        return context.Response.WriteAsJsonAsync(result);
    }
}

然后在Program.cs中添加这个中间件，全局异常中间件处理应该尽可能的靠前，这样才能够捕获尽可能多的异常。

app.UseMiddleware<ExceptionHandlerMiddleware>();

手动抛一个异常试试

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原始发表：2023-12-24，如有侵权请联系 cloudcommunity@tencent.com 删除

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