异常处理
Util 应用框架异常处理方法
本节介绍 Util 应用框架如何处理系统错误.
概述
系统在运行过程中可能发生错误.
系统错误可以简单分为两类:
系统异常
系统本身出现的错误.
业务异常
不满足业务规则出现的错误.
如何处理系统异常
如果发生系统异常,大多数情况下,你除了记录异常日志外,可能无法处理它们.
一个例外是并发异常.
当发生并发异常,可以通过重试再次提交,有可能成功处理.
另外一个问题,是否应该将系统异常消息返回给客户端?
系统异常消息与技术相关,客户无法理解它们.
而且系统异常消息可能包含敏感信息,返回给客户端可能更易受到攻击.
如何处理业务异常
业务异常表明没有满足某些业务规则,通常也无法自动处理.
如果能够自动处理的业务异常,应定义专用异常类型.
对于业务异常,除了记录异常日志外,还应把业务异常消息返回给客户端,以指示用户调整操作.
基础用法
.Net 使用异常 Exception 及派生异常来处理系统异常,但没有明确规定处理业务异常的类型.
Warning 业务异常
Util 应用框架定义了 Util.Exceptions.Warning 异常类型,Warning 从 Exception 派生,代表业务异常.
当你抛出 Exception 或派生异常类型时,异常消息仅在开发阶段返回给客户端.
一旦发布到生产环境,系统异常消息将被屏蔽,客户端收到消息: 系统忙，请稍后再试 .
throw new Exception( "未将对象引用设置到对象的实例" );
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对于业务规则导致的错误,你需要抛出 Warning 异常.
Warning 抛出的异常消息将返回到客户端,提示用户进行修改.
throw new Warning( "必须填写姓名" );
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GetMessage 工具方法
Warning 除了代表业务异常外,还提供了一个静态工具方法 GetMessage.
异常可能被其它异常包裹,要获得异常真正的消息,需要使用递归.
Warning.GetMessage 工具方法传入异常实例,递归获取异常消息,
var message = Warning.GetMessage( exception );
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ConcurrencyException 并发异常
Util 应用框架定义了并发异常 Util.Exceptions.ConcurrencyException.
不同的 .Net 组件抛出的并发异常类型可能不同, Util 使用 ConcurrencyException 进行统一包装.
可以通过重试的方式来解决并发异常.
下面是 Util 应用框架 Dapr 集成事件增加计数时并发处理的代码片断.
public virtual async Task IncrementAsync( CancellationToken cancellationToken = default ) { try { await Store.IncrementAsync( cancellationToken ); } catch ( ConcurrencyException ) { Log.LogDebug( "更新集成事件计数出现并发异常,即将重试" ); await IncrementAsync( cancellationToken ); } catch ( Exception exception ) { Log.LogError( exception, "更新集成事件计数失败" ); }}
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全局错误日志记录
Util 应用框架使用 ErrorLogFilterAttribute 过滤器来记录全局错误日志.
已在 Web Api 控制器基类 WebApiControllerBase 设置 [ErrorLogFilter] 过滤器.
全局异常处理
Util 应用框架使用 ExceptionHandlerAttribute 过滤器来处理全局异常.
已在 Web Api 控制器基类 WebApiControllerBase 设置 [ExceptionHandler] 过滤器.
[ExceptionHandler] 过滤器对异常消息进行处理,只有 Warning 异常消息才会返回给客户端.
源码解析
Warning 业务异常
Warning 代表业务异常,它的异常消息会返回给客户端.
GetMessage 方法使用递归获取内部异常消息.
/// <summary>/// 应用程序异常/// </summary>public class Warning : Exception { /// <summary> /// 初始化应用程序异常 /// </summary> /// <param name="exception">异常</param> public Warning( Exception exception ) : this( null, exception ) { }
/// <summary> /// 初始化应用程序异常 /// </summary> /// <param name="message">错误消息</param> /// <param name="exception">异常</param> /// <param name="code">错误码</param> /// <param name="httpStatusCode">Http状态码</param> public Warning( string message, Exception exception = null, string code = null, int? httpStatusCode = null ) : base( message ?? "", exception ) { Code = code; HttpStatusCode = httpStatusCode; IsLocalization = true; }
/// <summary> /// 错误码 /// </summary> public string Code { get; set; }
/// <summary> /// Http状态码 /// </summary> public int? HttpStatusCode { get; set; }
/// <summary> /// 是否本地化异常消息 /// </summary> public bool IsLocalization { get; set; }
/// <summary> /// 获取错误消息 /// </summary> /// <param name="isProduction">是否生产环境</param> public virtual string GetMessage( bool isProduction = false ) { return GetMessage( this ); }
/// <summary> /// 获取错误消息 /// </summary> public static string GetMessage( Exception ex ) { var result = new StringBuilder(); var list = GetExceptions( ex ); foreach( var exception in list ) AppendMessage( result, exception ); return result.ToString().Trim( Environment.NewLine.ToCharArray() ); }
/// <summary> /// 添加异常消息 /// </summary> private static void AppendMessage( StringBuilder result, Exception exception ) { if( exception == null ) return; result.AppendLine( exception.Message ); }
/// <summary> /// 获取异常列表 /// </summary> public IList<Exception> GetExceptions() { return GetExceptions( this ); }
/// <summary> /// 获取异常列表 /// </summary> /// <param name="ex">异常</param> public static IList<Exception> GetExceptions( Exception ex ) { var result = new List<Exception>(); AddException( result, ex ); return result; }
/// <summary> /// 添加内部异常 /// </summary> private static void AddException( List<Exception> result, Exception exception ) { if( exception == null ) return; result.Add( exception ); AddException( result, exception.InnerException ); }}
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ConcurrencyException 并发异常
ConcurrencyException 表示并发异常,统一包装其它组件产生的并发异常,并处理异常消息.
/// <summary>/// 并发异常/// </summary>public class ConcurrencyException : Warning { /// <summary> /// 消息 /// </summary> private readonly string _message;
/// <summary> /// 初始化并发异常 /// </summary> public ConcurrencyException() : this( "" ) { }
/// <summary> /// 初始化并发异常 /// </summary> /// <param name="exception">异常</param> public ConcurrencyException( Exception exception ) : this( "", exception ) { }
/// <summary> /// 初始化并发异常 /// </summary> /// <param name="message">错误消息</param> /// <param name="exception">异常</param> /// <param name="code">错误码</param> /// <param name="httpStatusCode">Http状态码</param> public ConcurrencyException( string message, Exception exception = null, string code = null, int? httpStatusCode = null ) : base( message, exception, code, httpStatusCode ) { _message = message; }
/// <inheritdoc /> public override string Message => $"{R.ConcurrencyExceptionMessage}.{_message}";
/// <inheritdoc /> public override string GetMessage( bool isProduction = false ) { if( isProduction ) return R.ConcurrencyExceptionMessage; return GetMessage(this); }}
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ErrorLogFilterAttribute 错误日志过滤器
[ErrorLogFilter] 错误日志过滤器记录全局异常日志.
/// <summary>/// 错误日志过滤器/// </summary>public class ErrorLogFilterAttribute : ExceptionFilterAttribute { /// <summary> /// 异常处理 /// </summary> public override void OnException( ExceptionContext context ) { if( context == null ) return; var log = context.HttpContext.RequestServices.GetService<ILogger<ErrorLogFilterAttribute>>(); var exception = context.Exception.GetRawException(); if( exception is Warning warning ) { log.LogWarning( warning, exception.Message ); return; } log.LogError( exception, exception.Message ); }}
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ExceptionHandlerAttribute 异常处理过滤器
[ExceptionHandler] 过滤器处理全局异常.
Exception 的扩展方法 GetPrompt 获取客户端友好的异常消息.
对于生产环境, Exception 异常消息将被替换为 系统忙，请稍后再试.
[ExceptionHandler] 过滤器还对异常消息的本地化进行了处理.
/// <summary>/// 异常处理过滤器/// </summary>public class ExceptionHandlerAttribute : ExceptionFilterAttribute { /// <summary> /// 异常处理 /// </summary> public override void OnException( ExceptionContext context ) { context.ExceptionHandled = true; var message = context.Exception.GetPrompt( Web.Environment.IsProduction() ); message = GetLocalizedMessages( context, message ); var errorCode = context.Exception.GetErrorCode() ?? StateCode.Fail; var httpStatusCode = context.Exception.GetHttpStatusCode() ?? 200; context.Result = GetResult( context, errorCode, message, httpStatusCode ); }
/// <summary> /// 获取本地化异常消息 /// </summary> protected virtual string GetLocalizedMessages( ExceptionContext context, string message ) { var exception = context.Exception.GetRawException(); if ( exception is Warning { IsLocalization: false } ) return message; var stringLocalizerFactory = context.HttpContext.RequestServices.GetService<IStringLocalizerFactory>(); if ( stringLocalizerFactory == null ) return message; var stringLocalizer = stringLocalizerFactory.Create( "Warning",null ); var localizedString = stringLocalizer[message]; if ( localizedString.ResourceNotFound == false ) return localizedString.Value; stringLocalizer = context.HttpContext.RequestServices.GetService<IStringLocalizer>(); if ( stringLocalizer == null ) return message; return stringLocalizer[message]; }
/// <summary> /// 获取结果 /// </summary> protected virtual IActionResult GetResult( ExceptionContext context, string code, string message, int? httpStatusCode ) { var options = GetJsonSerializerOptions( context ); var resultFactory = context.HttpContext.RequestServices.GetService<IResultFactory>(); if ( resultFactory == null ) return new Result( code, message, null, httpStatusCode, options ); return resultFactory.CreateResult( code, message, null, httpStatusCode, options ); }
/// <summary> /// 获取Json序列化配置 /// </summary> private JsonSerializerOptions GetJsonSerializerOptions( ExceptionContext context ) { var factory = context.HttpContext.RequestServices.GetService<IJsonSerializerOptionsFactory>(); if( factory != null ) return factory.CreateOptions(); return new JsonSerializerOptions { PropertyNamingPolicy = JsonNamingPolicy.CamelCase, Encoder = JavaScriptEncoder.Create( UnicodeRanges.All ), DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull, Converters = { new DateTimeJsonConverter(), new NullableDateTimeJsonConverter() } }; }}
/// <summary>/// 异常扩展/// </summary>public static class ExceptionExtensions { /// <summary> /// 获取异常提示 /// </summary> /// <param name="exception">异常</param> /// <param name="isProduction">是否生产环境</param> public static string GetPrompt( this Exception exception, bool isProduction = false ) { if( exception == null ) return null; exception = exception.GetRawException(); if( exception == null ) return null; if( exception is Warning warning ) return warning.GetMessage( isProduction ); return isProduction ? R.SystemError : exception.Message; }
/// <summary> /// 获取Http状态码 /// </summary> /// <param name="exception">异常</param> public static int? GetHttpStatusCode( this Exception exception ) { if ( exception == null ) return null; exception = exception.GetRawException(); if ( exception == null ) return null; if ( exception is Warning warning ) return warning.HttpStatusCode; return null; }
/// <summary> /// 获取错误码 /// </summary> /// <param name="exception">异常</param> public static string GetErrorCode( this Exception exception ) { if ( exception == null ) return null; exception = exception.GetRawException(); if ( exception == null ) return null; if ( exception is Warning warning ) return warning.Code; return null; }}
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