【IT168技术文档】

  Logging Application Block可以使开发人员在其应用程序中集成日志监测功能，看看随着2.0的推出给我们带来了哪些改变。

一．改进的地方

  1．Logging Application Block首先带来的是名称上的改变，在1.1下它的全称应该是Logging and Instrumentation Application Block，一般把它翻译为日志和检测应用程序块，而2.0下却完全变成了日志应用程序块。

  2．在1.1下，每个LogEntry只能被记录到一个Sink，而这种情况在2.0下已经不复存在，对于每个LogEntry对象，我们都可以通过Category指定很多的Sink。回忆一下在1.1时记录一个日志项：

LogEntry logEntry = new LogEntry();
logEntry.EventId = 100;
logEntry.Priority = 2;
logEntry.Message = "Informational message";
//只能设置一个
logEntry.Categorys = "UI Events";
Logger.Write(logEntry);
2.0下可以添加多次：
LogEntry logEntry = new LogEntry();
logEntry.EventId = 100;
logEntry.Priority = 2;
logEntry.Message = "Informational message";
//设置多个Category
logEntry.Categories.Add("Trace");
logEntry.Categories.Add("UI Events");
Logger.Write(logEntry);
3．可以在代码中查询哪些日志项将被过滤，例如：
LogEntry logEntry = new LogEntry();
logEntry.Priority = 2;
logEntry.Categories.Add("Trace");
logEntry.Categories.Add("UI Events");
if (Logger.ShouldLog(logEntry))
{
// Event will be logged according to currently configured filters.
}
else
{
// Event will not be logged. 
}

  4．配置文件的改变。在1.1下关于Logging & Instrumentation Application Block的信息记录在loggingconfiguration.config文件中，2.0下所有的信息都放在了Web.config或App.config中，如：

<configuration>
<configSections>
<section name="loggingConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.LoggingSettings, Microsoft.Practices.EnterpriseLibrary.Logging" />
</configSections>
<loggingConfiguration tracingEnabled="true" defaultCategory="General">
<logFilters>
<add
name="Category"
type="Microsoft.Practices.EnterpriseLibrary.Logging.Filters.CategoryFilter, Microsoft.Practices.EnterpriseLibrary.Logging"
categoryFilterMode="AllowAllExceptDenied">
<categoryFilters>
<add name="UI Events" />
</categoryFilters>
</add>
<add
name="Priority"
type="Microsoft.Practices.EnterpriseLibrary.Logging.Filters.PriorityFilter, Microsoft.Practices.EnterpriseLibrary.Logging"
minimumPriority="2"
/>
<add name="LogEnabled Filter"
type="Microsoft.Practices.EnterpriseLibrary.Logging.Filters.LogEnabledFilter, Microsoft.Practices.EnterpriseLibrary.Logging, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null"
enabled="true"
/>
</logFilters>
</loggingConfiguration>
</configuration>