C#实现自动化Log日志

概述

在开发项目的时候，我们不免要使用Log记录日志，使用最多的是Log4Net和EntLib Log，在需要记录日志的代码处加入log.Write(日志信息)，假设我需要跟踪业务方法，记录方法的传递参数，执行时间，返回数据等；或者我需要查看方法的调用关系，希望进入方法的时候自动记录参数信息，出方法时记录结果和执行时间信息。这时就是一个典型的AOP运用，Java在AOP方面是很容易实现的，因为java有类加载器。但是.Net在AOP方面就不怎么容易，严格意义上.Net没有真正的AOP。这话并不代表.Net不能实现AOP，比如：PostSharp和Enterprise library就能实现。.

先介绍一下PostSharp，我们知道.net代码将编译成MSIL（微软中间语言），然后CPU将MSIL的exe文件生成本地CPU的二进制文件格式，PostSharp就是在编译过程中加入IL代码，因而完成AOP功能。

缺点：编译器需要PostSharp组件，维护代码困难，因为IL代码不好识别；

优点：使用方便（PostSharp2是收费版，破解也比较方便，在此不介绍破解）

这里我重点介绍如何使用Enterprise Library实现自动化Log。

实现

1.首先我们需要下载Enterprise Library，最新为5.0版本；

2.新建一个控制台项目，并添加以下程序集

Microsoft.Practices.EnterpriseLibrary.Common

Microsoft.Practices.EnterpriseLibrary.Logging

Microsoft.Practices.EnterpriseLibrary.PolicyInjection

Microsoft.Practices.ServiceLocation

Microsoft.Practices.Unity

Microsoft.Practices.Unity.Interception

3.添加AutoLogCallHandler类，实现ICallHandler接口

这个类是执行调用目标方法，在调用目标方法前获取方法的参数信息，并用EntLib Log记录日志；

方法结束后，再次记录日志，并统计执行时间和异常处理

using System;using System.Collections.Generic;using System.Linq;using System.Text;using Microsoft.Practices.Unity.InterceptionExtension;using Microsoft.Practices.EnterpriseLibrary.Logging;using Microsoft.Practices.EnterpriseLibrary.Common.Configuration;using System.Diagnostics;using System.Reflection; namespace AutoLog {  public class AutoLogCallHandler:ICallHandler {     private LogWriter logWriter = EnterpriseLibraryContainer.Current.GetInstance<LogWriter>();     public AutoLogCallHandler() { }     public IMethodReturn Invoke(IMethodInvocation input, GetNextHandlerDelegate getNext) {      StringBuilder sb = null;      ParameterInfo pi = null;       string methodName = input.MethodBase.Name;      logWriter.Write(string.Format("Enter method " + methodName));        if (input.Arguments != null && input.Arguments.Count > 0) {        sb = new StringBuilder();        for (int i = 0; i < input.Arguments.Count; i++) {          pi = input.Arguments.GetParameterInfo(i);          sb.Append(pi.Name).Append(" : ").Append(input.Arguments[i]).AppendLine();        }        logWriter.Write(sb.ToString());      }                 Stopwatch sw = new Stopwatch();      sw.Start();       IMethodReturn result = getNext()(input, getNext);      //如果发生异常则，result.Exception != null      if (result.Exception != null) {        logWriter.Write("Exception:" + result.Exception.Message);        //必须将异常处理掉，否则无法继续执行        result.Exception = null;      }       sw.Stop();      logWriter.Write(string.Format("Exit method {0}, use {1}.",methodName, sw.Elapsed));       return result;    }     public int Order { get; set; }  }}

4.要自动化日志就需要创建一个标记属性，指定方法能自动进行日志
这里就创建AutoLogCallHandlerAttribute标记属性

using System;using System.Collections.Generic;using System.Linq;using System.Text;using Microsoft.Practices.Unity.InterceptionExtension;using Microsoft.Practices.EnterpriseLibrary.Logging;using System.Diagnostics;using Microsoft.Practices.EnterpriseLibrary.Common.Configuration; namespace AutoLog {   public class AutoLogCallHandlerAttribute:HandlerAttribute {     public override ICallHandler CreateHandler(Microsoft.Practices.Unity.IUnityContainer container) {      return new AutoLogCallHandler() { Order = this.Order };    }  }}

5.创建实体类
注意：我在Work和ToString方法上方加上了AutoLogCallHandler属性，它是AutoLogCallHandlerAttribute的简写形式。用以指示这两个方法用AutoLogCallHandler的Invoke来处理。

using System;using System.Collections.Generic;using System.Linq;using System.Text;using Microsoft.Practices.Unity; namespace AutoLog {   public class Employee : MarshalByRefObject   {        public Employee() {}     public string Name { get; set; }     [AutoLogCallHandler()]    public void Work() {      Console.WriteLine("Now is {0},{1} is working hard!",DateTime.Now.ToShortTimeString(),Name);      throw new Exception("Customer Exception");    }     [AutoLogCallHandler()]    public override string ToString() {      return string.Format("I'm {0}.",Name);    }  }}

6.测试代码
注意：必须使用PolicyInjection.Create<Employee>()来创建对象，不然无法实现。

using System;using System.Collections.Generic;using System.Linq;using System.Text;using Microsoft.Practices.EnterpriseLibrary.PolicyInjection;using Microsoft.Practices.Unity;using Microsoft.Practices.EnterpriseLibrary.Logging;using Microsoft.Practices.EnterpriseLibrary.Common.Configuration; namespace AutoLog {  class Program {     private static LogWriter logWriter = EnterpriseLibraryContainer.Current.GetInstance<LogWriter>();     static void Main(string[] args) {        Employee emp = PolicyInjection.Create<Employee>();       emp.Name = "Lele";       emp.Work();      Console.WriteLine(emp);    }  }}

7.还需要用EntLib的配置工具完成Log配置，将Log信息写入Trace.log文件中

<?xml version="1.0"?><configuration>    <configSections>        <section name="loggingConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.LoggingSettings, Microsoft.Practices.EnterpriseLibrary.Logging, Version=5.0.505.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="true" />    </configSections>    <loggingConfiguration name="" tracingEnabled="true" defaultCategory="General">        <listeners>            <add name="Flat File Trace Listener" type="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.FlatFileTraceListener, Microsoft.Practices.EnterpriseLibrary.Logging, Version=5.0.505.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"                listenerDataType="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.FlatFileTraceListenerData, Microsoft.Practices.EnterpriseLibrary.Logging, Version=5.0.505.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"                fileName="trace.log" formatter="Text Formatter" />        </listeners>        <formatters>            <add type="Microsoft.Practices.EnterpriseLibrary.Logging.Formatters.TextFormatter, Microsoft.Practices.EnterpriseLibrary.Logging, Version=5.0.505.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"                template="Timestamp: {timestamp}{newline}Message: {message}{newline}Category: {category}{newline}Priority: {priority}{newline}EventId: {eventid}{newline}Severity: {severity}{newline}Title:{title}{newline}Machine: {localMachine}{newline}App Domain: {localAppDomain}{newline}ProcessId: {localProcessId}{newline}Process Name: {localProcessName}{newline}Thread Name: {threadName}{newline}Win32 ThreadId:{win32ThreadId}{newline}Extended Properties: {dictionary({key} - {value}{newline})}"                name="Text Formatter" />        </formatters>        <categorySources>            <add switchValue="All" name="General">                <listeners>                    <add name="Flat File Trace Listener" />                </listeners>            </add>        </categorySources>        <specialSources>            <allEvents switchValue="All" name="All Events" />            <notProcessed switchValue="All" name="Unprocessed Category" />            <errors switchValue="All" name="Logging Errors & Warnings">                <listeners>                    <add name="Flat File Trace Listener" />                </listeners>            </errors>        </specialSources>    </loggingConfiguration>    <startup>        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/>    </startup></configuration>

好了，测试一下，控制台输入：
Now is 14:03,Lele is working hard!
I'm Lele.
再看看Trace.log文件内容：

----------------------------------------Timestamp: 2012/3/19 6:03:00
Message: Enter method Work
Category: General
Priority: -1
EventId: 1
Severity: Information
Title:
Machine: PC4
App Domain: AutoLog.exe
ProcessId: 4200
Process Name: D:\Codes\Enterprise Library\Enterprise Library Demos\PIAB\Demo\AutoLog\bin\Debug\AutoLog.exe
Thread Name: 
Win32 ThreadId:4000
Extended Properties: --------------------------------------------------------------------------------Timestamp: 2012/3/19 6:03:00
Message: Exception:Customer Exception
Category: General
Priority: -1
EventId: 1
Severity: Information
Title:
Machine: PC4
App Domain: AutoLog.exe
ProcessId: 4200
Process Name: D:\Codes\Enterprise Library\Enterprise Library Demos\PIAB\Demo\AutoLog\bin\Debug\AutoLog.exe
Thread Name: 
Win32 ThreadId:4000
Extended Properties: --------------------------------------------------------------------------------Timestamp: 2012/3/19 6:03:00
Message: Exit method Work, use 00:00:00.0024272.
Category: General
Priority: -1
EventId: 1
Severity: Information
Title:
Machine: PC4
App Domain: AutoLog.exe
ProcessId: 4200
Process Name: D:\Codes\Enterprise Library\Enterprise Library Demos\PIAB\Demo\AutoLog\bin\Debug\AutoLog.exe
Thread Name: 
Win32 ThreadId:4000
Extended Properties: --------------------------------------------------------------------------------Timestamp: 2012/3/19 6:03:00
Message: Enter method ToString
Category: General
Priority: -1
EventId: 1
Severity: Information
Title:
Machine: PC4
App Domain: AutoLog.exe
ProcessId: 4200
Process Name: D:\Codes\Enterprise Library\Enterprise Library Demos\PIAB\Demo\AutoLog\bin\Debug\AutoLog.exe
Thread Name: 
Win32 ThreadId:4000
Extended Properties: --------------------------------------------------------------------------------Timestamp: 2012/3/19 6:03:00
Message: Exit method ToString, use 00:00:00.0001410.
Category: General
Priority: -1
EventId: 1
Severity: Information
Title:
Machine: PC4
App Domain: AutoLog.exe
ProcessId: 4200
Process Name: D:\Codes\Enterprise Library\Enterprise Library Demos\PIAB\Demo\AutoLog\bin\Debug\AutoLog.exe
Thread Name: 
Win32 ThreadId:4000
Extended Properties: ----------------------------------------

实现了自动化Log后，回过头来再看第5步，Employee继承了MarshalByRefObject，一般我们的业务类或数据访问类都有基类，那么我们就需要使用接口
这里我添加一个IEmployee接口，里面就Work方法（ToString是重写Object的）。

using System.Collections.Generic;using System.Linq;using System.Text;using Microsoft.Practices.Unity; namespace AutoLog {   public interface IEmployee {    void Work();  }   public class Employee : IEmployee   {        public Employee() {      //this.Name = "Lele";    }     public string Name { get; set; }     [AutoLogCallHandler()]    public void Work() {      Console.WriteLine("Now is {0},{1} is working hard!",DateTime.Now.ToShortTimeString(),Name);      throw new Exception("Customer Exception");    }     [AutoLogCallHandler()]    public override string ToString() {      return string.Format("I'm {0}.",Name);    }  }}

然后在测试类改动一下

using System;using System.Collections.Generic;using System.Linq;using System.Text;using Microsoft.Practices.EnterpriseLibrary.PolicyInjection;using Microsoft.Practices.Unity;using Microsoft.Practices.EnterpriseLibrary.Logging;using Microsoft.Practices.EnterpriseLibrary.Common.Configuration; namespace AutoLog {  class Program {     private static LogWriter logWriter = EnterpriseLibraryContainer.Current.GetInstance<LogWriter>();     static void Main(string[] args) {       IEmployee emp = PolicyInjection.Create<Employee, IEmployee>();       emp.Work();      Console.WriteLine(emp);    }  }}

概述

实现

董川民