分类:
2008-05-27 21:28:08
建立一个Exception对象后你可以将对象返回,但不应该这样使用,更好的方法是用throw关键字来代替。throw用来抛出异常:
throw new Exception( "my message", 44 );
throw 将脚本的执行中止,并使相关的Exception对象对客户代码可用。
以下是改进过的getCommandObject()
方法
:
index_php5.php
// PHP 5
require_once(
'cmd_php5/Command.php'
);
class
CommandManager
{
private
$cmdDir
=
"cmd_php5"
;
function
getCommandObject
(
$cmd
) {
$path
=
"{$this->cmdDir}/{$cmd}.php"
;
if (!
(
$path
)) {
throw new
Exception
(
"Cannot find $path"
);
}
require_once
$path
;
if (!
(
$cmd
)) {
throw new
Exception
(
"class $cmd does not exist"
);
}
$class
= new
ReflectionClass
(
$cmd
);
if (!
$class
->
isSubclassOf
(new
ReflectionClass
(
'Command'
))) {
throw new
Exception
(
"$cmd is not a Command"
);
}
return new
$cmd
();
}
}
?>
代码中我们使用了PHP5的反射(Reflection)API来判断所给的类是否是属于Command
类型。在错误的路径下执行本脚本将会报出这样的错误:
Fatal error: Uncaught exception 'Exception' with message 'Cannot find command/xrealcommand.php' in /home/xyz/BasicException.php:10
Stack trace:
#0 /home/xyz/BasicException.php(26):
CommandManager->getCommandObject('xrealcommand')
#1 {main}
thrown in /home/xyz/BasicException.php on line 10