阅读本文之前,请先阅读:
上一篇中我们介绍了如何去配置Logging Application Block,本文将主要介绍Logging Application Block 的基本操作以及Formatter和Trace Listeners 的自定义方法，首先我们来看如何将一个事件日志写入到一个文本文件中。 假设我们按照上一篇的操作配置了Logging Application Block，那么配置文件中的信息如下：
< loggingConfiguration name ="Logging Application Block" tracingEnabled ="true" defaultCategory ="General" logWarningsWhenNoCategoriesMatch ="true" > < listeners > < add fileName ="trace.log" header ="----------------------------------------" footer ="----------------------------------------" formatter ="SHY520 Formatter" listenerDataType ="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.FlatFileTraceListenerData, Microsoft.Practices.EnterpriseLibrary.Logging, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null" traceOutputOptions ="None" type ="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.FlatFileTraceListener, Microsoft.Practices.EnterpriseLibrary.Logging, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null" name ="SHY520 Listeners" /> < add source ="Enterprise Library Logging" formatter ="Text Formatter" log ="Application" machineName ="" listenerDataType ="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.FormattedEventLogTraceListenerData, Microsoft.Practices.EnterpriseLibrary.Logging, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null" traceOutputOptions ="None" type ="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.FormattedEventLogTraceListener, Microsoft.Practices.EnterpriseLibrary.Logging, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null" name ="Formatted EventLog TraceListener" /> </ listeners > < formatters > < add template ="Timestamp: {timestamp} Message: {message} Category: {category} Priority: {priority} EventId: {eventid} Severity: {severity} Title:{title} Machine: {machine} Application Domain: {appDomain} Process Id: {processId} Process Name: {processName} Win32 Thread Id: {win32ThreadId} Thread Name: {threadName} Extended Properties: {dictionary({key} - {value} )}" type ="Microsoft.Practices.EnterpriseLibrary.Logging.Formatters.TextFormatter, Microsoft.Practices.EnterpriseLibrary.Logging, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null" name ="Text Formatter" /> < add template ="Timestamp: {timestamp} Message: {message} Category: {category} Priority: {priority} EventId: {eventid} Severity: {severity} Title:{title} Machine: {machine} Application Domain: {appDomain} Process Id: {processId} Process Name: {processName} Win32 Thread Id: {win32ThreadId} Thread Name: {threadName} Extended Properties: {dictionary({key} - {value} )}" type ="Microsoft.Practices.EnterpriseLibrary.Logging.Formatters.TextFormatter, Microsoft.Practices.EnterpriseLibrary.Logging, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null" name ="SHY520 Formatter" /> </ formatters > < logFilters > < add categoryFilterMode ="AllowAllExceptDenied" type ="Microsoft.Practices.EnterpriseLibrary.Logging.Filters.CategoryFilter, Microsoft.Practices.EnterpriseLibrary.Logging, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null" name ="Category Filter" /> </ logFilters > < categorySources > < add switchValue ="All" name ="General" > < listeners > < add name ="SHY520 Listeners" /> </ 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 ="Formatted EventLog TraceListener" /> </ listeners > </ errors > </ specialSources > </ loggingConfiguration > [TestMethod] public void DoLog()
{ 
//创建一个日志条目 LogEntry log = new LogEntry(); //指定该日志所属类别 log.Categories.Add("General"); //日志标题 log.Title = "SHY520's Tests"; log.Message = "there is log information"; //优先级 log.Priority = 0; Logger.Write(log);
} 
上图中，我们可以看到我们在程序中记录的一些日志信息，我们还可以记录一些额外的信息，这些信息是键值对应的，在1.0版本中我们用Hashtable,这里我们用的是一个泛型的Dictionary类型，代码如下： [TestMethod] public void LoggEntry() { LogEntry log = new LogEntry(); //事件ID log.EventId = 2000; //日志优先级 log.Priority = 2; log.Message = "Test LogEntry 2"; //日志类别 ICollection<string> coll = new List<string>(); coll.Add("General"); log.Categories = coll; //添加额外信息 Dictionary<string, object> dic = new Dictionary<string, object>(); dic.Add("name", "SHY520"); dic.Add("sex","男"); dic.Add("age", "22"); log.ExtendedProperties = dic; //写入日志 Logger.Write(log); } 
下面我们来介绍一下过滤器的用法：实现方法很简单，这里我们假设我们已经按照上一篇文章中的方法配置好了一个Category Filter,在Category Filter中我们可以设置要过滤掉哪种类别的事件日志，具体实现方式有两种，如下：方法一： [TestMethod] public void TestFilter1() { LogEntry logEntry = new LogEntry(); logEntry.Priority = 2; logEntry.Categories.Add("General"); //ShouldLog()方法根据Filter配置返回是否需要记录日志 if (Logger.GetFilter<CategoryFilter>().ShouldLog(logEntry.Categories))
{ //TODO:记录日志 Logger.Write(logEntry);
} } [TestMethod] public void TestFilter2() { LogEntry logEntry = new LogEntry(); logEntry.Priority = 2; logEntry.Categories.Add("General"); if (Logger.ShouldLog(logEntry)) { Logger.Write(logEntry); } } using System; using System.Collections.Generic; using System.Text; using Microsoft.Practices.EnterpriseLibrary.Common.Configuration; using Microsoft.Practices.EnterpriseLibrary.Logging.Configuration; using Microsoft.Practices.EnterpriseLibrary.Logging; using Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners; namespace Enterprise_Library_2 { [ConfigurationElementType(typeof(CustomTraceListenerData))] public class MyListener : CustomTraceListener { public override void TraceData(System.Diagnostics.TraceEventCache eventCache, string source, System.Diagnostics.TraceEventType eventType, int id, object data) { if (data is LogEntry && this.Formatter != null) { this.WriteLine(this.Formatter.Format(data as LogEntry)); } else { this.WriteLine(data.ToString()); } } public override void Write(string message) { //TODO：添加自己所需的逻辑 } public override void WriteLine(string message) { //TODO：添加自己所需的逻辑 } }} 接下来我们来看看如何自定义Formatter,实现的方法和上面类似，首先新建一个类MyFormatter,继承ILogFormatter接口，同时加上[ConfigurationElementType(typeof(CustomFormatterData))]的Attribute,完整的代码如下：
using System; using System.Collections.Generic; using System.Text; using System.Collections.Specialized; using Microsoft.Practices.EnterpriseLibrary.Common.Configuration; using Microsoft.Practices.EnterpriseLibrary.Logging.Configuration; using Microsoft.Practices.EnterpriseLibrary.Logging; using Microsoft.Practices.EnterpriseLibrary.Logging.Formatters; namespace Enterprise_Library_2 { [ConfigurationElementType(typeof(CustomFormatterData))] public class MyFormatter : ILogFormatter { public MyFormatter(NameValueCollection nv) { //注意：构造函数的参数必须是NameValueCollection类型的 } public string Format(LogEntry log) { string result = string.Empty; //TODO:此处添加我们个性化的Formatter逻辑 return result; } }} 希望对初学者有所帮助,同时也欢迎Enterprise Library学习者一起共同交流经验。
Email :