3．捕获并记录ASP.NET异常

    首先需要添加如下引用：

Microsoft.Practices.EnterpriseLibrary.Logging.dll
Microsoft.Practices.EnterpriseLibrary.Logging.Database.dll
Microsoft.Practices.EnterpriseLibrary.Data.dll 

    为Web站点添加Global.asax文件，并且在Application_Error编写如下代码，这样在有异常发生时应用程序块会把异常信息记录到数据库中：

<%@ Application Language="C#" %>
<%@ Import Namespace="Microsoft.Practices.EnterpriseLibrary.Logging" %>
<script runat="server">
void Application_Error(object sender, EventArgs e)
{
// Code that runs when an unhandled error occurs 
Exception ex = Server.GetLastError().GetBaseException();
LogEntry log = new LogEntry();
log.Message = ex.Message +
"\r\nSOURCE: " + ex.Source +
"\r\nFORM: " + Request.Form.ToString() +
"\r\nQUERYSTRING: " + Request.QueryString.ToString() +
"\r\nTARGETSITE: " + ex.TargetSite +
"\r\nSTACKTRACE: " + ex.StackTrace;
Logger.Write(log);
}
</script><%@ Application Language="C#" %>
<%@ Import Namespace="Microsoft.Practices.EnterpriseLibrary.Logging" %>
<script runat="server">
void Application_Error(object sender, EventArgs e)
{
// Code that runs when an unhandled error occurs 
Exception ex = Server.GetLastError().GetBaseException();
LogEntry log = new LogEntry();
log.Message = ex.Message +
"\r\nSOURCE: " + ex.Source +
"\r\nFORM: " + Request.Form.ToString() +
"\r\nQUERYSTRING: " + Request.QueryString.ToString() +
"\r\nTARGETSITE: " + ex.TargetSite +
"\r\nSTACKTRACE: " + ex.StackTrace;
Logger.Write(log);
}
</script> 

    4．创建一个未处理的异常

    在Default.aspx.cs的Page_Load事件中制造一个异常信息

public partial class _Default : System.Web.UI.Page {
protected void Page_Load(object sender, EventArgs e)
{
int error = Int32.Parse("bbbbb");
}
} 

    运行程序后，可以看到数据库表中会多出一条记录：

    其中Message的内容：

Input string was not in a correct format.
SOURCE: mscorlib
FORM:
QUERYSTRING:
TARGETSITE: Void StringToNumber(System.String, System.Globalization.NumberStyles, NumberBuffer ByRef, System.Globalization.NumberFormatInfo, Boolean)
STACKTRACE: at System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal)
at System.Number.ParseInt32(String s, NumberStyles style, NumberFormatInfo info)
at System.Int32.Parse(String s)
at _Default.Page_Load(Object sender, EventArgs e) in c:\Inetpub\wwwroot\EntLibDemo2\Default.aspx.cs:line 15
at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e)
at System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e)
at System.Web.UI.Control.OnLoad(EventArgs e)
at System.Web.UI.Control.LoadRecursive()
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

    这样我们就实现了用Logging Application Block对未处理异常信息的记录，如果要记录到文本文件或者发送Email，只需要在第2步新建Flat File Trace Listener或者Email Trace Listener，使用文本文件时要注意设置文件夹的权限。