通常，这样的处理可以正常的工作，但却不是恰当的解决方法。我们希望不仅把异常信息传递给用户，而且要求在不影响Thread继续工作的前提下，由Application
或系统单元(致命异常)来进一步处理异常。要做这样处理，首先，我们在自己的 Thread
类里定义一个异常对象，由这个对象承载各种要处理的异常类实例。其次，建立响应异常的同步事件。对EAbort消息加以抑制，对来自程序本身的异常由Application处理，对系统级异常，一般交与操作系统来完成。以下是一个简单的异常捕捉应用框架。
unit Unit1;
interface
uses
Windows, Messages, SysUtils,
Classes,
Graphics, Controls, Forms, Dialogs,
StdCtrls;
type
TForm1 = class(TForm)
Button1:
TButton;
procedure Button1Click(Sender: TObject);
private
{
Private declarations }
Procedure RunThread;
public
{ Public
declarations }
end;
TBaseThread =
class(TThread)
private
FException: Exception;
procedure
DoHandleException;
protected
procedure Execute;
override;
//父类函数为虚，在子类再重载其而处理具体事宜
procedure HandleException;
virtual;
public
end;
TMyThread =
class(TBaseThread)
private
...
protected
procedure Execu
override;
procedure HandleException; override;
...
public
...
end;
var
Form1:
TForm1;
implementation
{$R *.DFM}
procedure
TBaseThread.DoHandleException;
begin
// 关闭当前主窗体对鼠标的响应
if GetCapture
$#@60;$#@62; 0 then SendMessage(GetCapture, WM_CANCELMODE, 0, 0);
//
判断异常的范围并做相应处理
if FException is Exception
then
Application.ShowException(FException)
else
SysUtils.ShowException(FException,
nil);
...
end;
procedure
TBaseThread.Execute;
begin
FException :=
nil;
try
...
//处理一些事情
except
//如果发生了异常
HandleException;
end;
end;
procedure
TBaseThread.HandleException;
begin
//得到当前异常对象
FException :=
Exception(ExceptObject);
try
//避免因 EAbort 消息使程序推出
if not
(FException is EAbort)
then
Synchronize(DoHandleException);
finally
FException :=
nil;
end;
end;
procedure
TMyThread.Execute;
begin
...
end;
procedure
TMyThread.HandleException;
begin
...
end;
procedure
TForm1.RunThread;
begin
//为 TMyThread 类创建实例
with
TMyThread.Create(True) do
begin
FreeOnTerminate := True;
Resume;
end;
end;
...
