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为了使日志类更加灵活，我们自己写一个日志接口，自己实现它：
public interface ILogger { void Information(string message); void Information(string fmt, params object[] vars); void Information(Exception exception, string fmt, params object[] vars); void Warning(string message); void Warning(string fmt, params object[] vars); void Warning(Exception exception, string fmt, params object[] vars); void Error(string message); void Error(string fmt, params object[] vars); void Error(Exception exception, string fmt, params object[] vars); void TraceApi(string componentName, string method, TimeSpan timespan); void TraceApi(string componentName, string method, TimeSpan timespan, string properties); void TraceApi(string componentName, string method, TimeSpan timespan, string fmt, params object[] vars); }
然后依靠System.Diagnostics的Trace方法实现它：
using System; using System.Diagnostics; using System.Text; namespace ContosoUniversity.Logging { public class Logger : ILogger { public void Information(string message) { Trace.TraceInformation(message); } public void Information(string fmt, params object[] vars) { Trace.TraceInformation(fmt, vars); } public void Information(Exception exception, string fmt, params object[] vars) { Trace.TraceInformation(FormatExceptionMessage(exception, fmt, vars)); } public void Warning(string message) { Trace.TraceWarning(message); } public void Warning(string fmt, params object[] vars) { Trace.TraceWarning(fmt, vars); } public void Warning(Exception exception, string fmt, params object[] vars) { Trace.TraceWarning(FormatExceptionMessage(exception, fmt, vars)); } public void Error(string message) { Trace.TraceError(message); } public void Error(string fmt, params object[] vars) { Trace.TraceError(fmt, vars); } public void Error(Exception exception, string fmt, params object[] vars) { Trace.TraceError(FormatExceptionMessage(exception, fmt, vars)); } public void TraceApi(string componentName, string method, TimeSpan timespan) { TraceApi(componentName, method, timespan, ""); } public void TraceApi(string componentName, string method, TimeSpan timespan, string fmt, params object[] vars) { TraceApi(componentName, method, timespan, string.Format(fmt, vars)); } public void TraceApi(string componentName, string method, TimeSpan timespan, string properties) { string message = String.Concat("Component:", componentName, ";Method:", method, ";Timespan:", timespan.ToString(), ";Properties:", properties); Trace.TraceInformation(message); } private static string FormatExceptionMessage(Exception exception, string fmt, object[] vars) { // Simple exception formatting: for a more comprehensive version see // http://code.msdn.microsoft.com/windowsazure/Fix-It-app-for-Building-cdd80df4 var sb = new StringBuilder(); sb.Append(string.Format(fmt, vars)); sb.Append(" Exception: "); sb.Append(exception.ToString()); return sb.ToString(); } } }
接下来我们可以实现EF中的拦截类，来拦截给数据库发送的消息并记录到日志中：
using ContosoUniversity.Logging; using System; using System.Collections.Generic; using System.Data.Entity.Infrastructure.Interception; using System.Diagnostics; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Data.Common; namespace ContosoUniversity.DAL { public class SchoolInterceptorLogging : DbCommandInterceptor { private ILogger _logger = new Logger(); private readonly Stopwatch _stopwatch = new Stopwatch(); public override void ScalarExecuting(DbCommand command, DbCommandInterceptionContext<object> interceptionContext) { base.ScalarExecuting(command, interceptionContext); _stopwatch.Restart(); } public override void ScalarExecuted(DbCommand command, DbCommandInterceptionContext<object> interceptionContext) { _stopwatch.Stop(); if (interceptionContext.Exception != null) { _logger.Error(interceptionContext.Exception, "Error executing command: {0}", command.CommandText); } else { _logger.TraceApi("SQL Database", "SchoolInterceptor.ScalarExecuted", _stopwatch.Elapsed, "Command: {0}: ", command.CommandText); } base.ScalarExecuted(command, interceptionContext); } public override void NonQueryExecuting(DbCommand command, DbCommandInterceptionContext<int> interceptionContext) { base.NonQueryExecuting(command, interceptionContext); _stopwatch.Restart(); } public override void NonQueryExecuted(DbCommand command, DbCommandInterceptionContext<int> interceptionContext) { _stopwatch.Stop(); if (interceptionContext.Exception != null) { _logger.Error(interceptionContext.Exception, "Error executing command: {0}", command.CommandText); } else { _logger.TraceApi("SQL Database", "SchoolInterceptor.NonQueryExecuted", _stopwatch.Elapsed, "Command: {0}: ", command.CommandText); } base.NonQueryExecuted(command, interceptionContext); } public override void ReaderExecuting(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext) { base.ReaderExecuting(command, interceptionContext); _stopwatch.Restart(); } public override void ReaderExecuted(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext) { _stopwatch.Stop(); if (interceptionContext.Exception != null) { _logger.Error(interceptionContext.Exception, "Error executing command: {0}", command.CommandText); } else { _logger.TraceApi("SQL Database", "SchoolInterceptor.ReaderExecuted", _stopwatch.Elapsed, "Command: {0}: ", command.CommandText); } base.ReaderExecuted(command, interceptionContext); } } }
如果你写过SqlHelper的话，应该对上述代码不陌生的，简而言之就是当你没调用一次数据库操作时，这次操作的内容就会被记录下来。对于成功的查询，他记录到了Information中，对于失败的查询，记录到了Error中。
我们之后来注册它，首先来到根目录下的Global.asax：
DbInterception.Add(new SchoolInterceptorLogging());当然，我们无论在哪里注册都可以，只有注册了之后，我们才会将querys记录到日志中。
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原文地址：http://www.cnblogs.com/blackerXHunter/p/4556859.html
