PHP 面向对象编程和设计模式 (4)_PHP教程

<span>Exception</span><span> {

    </span><span>/*</span><span> 属性 </span><span>*/</span>
    <span>protected</span> <span>string</span> <span>$message</span> ;        <span>//</span><span>异常消息内容</span>
    <span>protected</span> int <span>$code</span> ;            <span>//</span><span>异常代码</span>
    <span>protected</span> <span>string</span> <span>$file</span> ;        <span>//</span><span>抛出异常的文件名</span>
    <span>protected</span> int <span>$line</span> ;            <span>//</span><span>抛出异常在该文件中的行号</span>

    <span>/*</span><span> 方法 </span><span>*/</span>
    <span>public</span> __construct ([ <span>string</span> <span>$message</span> = "" [, int <span>$code</span> = 0 [, <span>Exception</span> <span>$previous</span> = <span>NULL</span> ]]] )    <span>//</span><span>异常构造函数</span>
    <span>final</span> <span>public</span> <span>string</span> getMessage ( void )            <span>//</span><span>获取异常消息内容</span>
    <span>final</span> <span>public</span> <span>Exception</span> getPrevious ( void )        <span>//</span><span>返回异常链中的前一个异常</span>
    <span>final</span> <span>public</span> int getCode ( void )                <span>//</span><span>获取异常代码</span>
    <span>final</span> <span>public</span> <span>string</span> getFile ( void )            <span>//</span><span>获取发生异常的程序文件名称</span>
    <span>final</span> <span>public</span> int getLine ( void )                <span>//</span><span>获取发生异常的代码在文件中的行号</span>
    <span>final</span> <span>public</span> <span>array</span> getTrace ( void )            <span>//</span><span>获取异常追踪信息</span>
    <span>final</span> <span>public</span> <span>string</span> getTraceAsString ( void )    <span>//</span><span>获取字符串类型的异常追踪信息</span>
    <span>public</span> <span>string</span> __toString ( void )                <span>//</span><span>将异常对象转换为字符串</span>
    <span>final</span> <span>private</span> void __clone ( void )                <span>//</span><span>异常克隆</span>
}

<span>function</span><span> connectToDatabase()
{    
    </span><span>if</span>(!<span>$link</span> = <span>mysql_connect</span>("myhost","myuser","mypassw","mybd"<span>))
    {
        </span><span>throw</span> <span>new</span> <span>Exception</span>("could not connect to the database."<span>);
    }
}

</span><span>try</span><span>
{
    connectToDatabase();
}
</span><span>catch</span>(<span>Exception</span> <span>$e</span><span>)
{</span><span>echo</span> <span>$e</span>-><span>getMessage();
}</span>

<span>class</span> MyException <span>extends</span> <span>Exception</span><span>
{
    </span><span>protected</span> <span>$ErrorInfo</span><span>;

    </span><span>//</span><span>构造函里处理一些逻辑，然后将一些信息传递给基类</span>
    <span>public</span> <span>function</span> __construct(<span>$message</span>=<span>null</span>,<span>$code</span>=0<span>)
    {
        </span><span>$this</span>->ErrorInfo = '自定义错误类的错误信息'<span>;
        parent</span>::__construct(<span>$message</span>,<span>$code</span><span>);
    }    

    </span><span>//</span><span>提供获取自定义类信息的方法</span>
    <span>public</span> <span>function</span><span> GetErrorInfo()
    {
        </span><span>return</span> <span>$this</span>-><span>ErrorInfo;
    }

    </span><span>/*</span><span>*
     *
     *这里还可以添加异常日志,只需在上面的构造函数里调用就可以了
     *
     </span><span>*/</span>

    <span>public</span> <span>function</span> <span>log</span>(<span>$file</span><span>)
    {
        </span><span>file_put_contents</span>(<span>$fiel</span>,<span>$this</span>->__toString(),<span>FILE_APPEND);
    }
}

</span><span>function</span><span> connectToDatabase()
{    
    </span><span>throw</span> <span>new</span> MyException("ErrorMessage"<span>);
}

</span><span>try</span><span>
{    
    connectToDatabase();
}
</span><span>catch</span>(MyException <span>$e</span><span>)
{    
    </span><span>echo</span> <span>$e</span>->getMessage() . "\n"<span>;
    </span><span>echo</span> <span>$e</span>-><span>GetErrorInfo();
}</span>

<span>function</span> ExceptionLogger(<span>$exception</span><span>)
{
    </span><span>$file</span>='ExceptionLog.log'<span>;
    </span><span>file_put_contents</span>(<span>$fiel</span>,<span>$exception</span>->__toString(),<span>FILE_APPEND);
}

</span><span>set_exception_handler</span>(ExceptionLogger);

<span>try</span><span>
{
    </span><span>#</span><span>code...</span>
<span>}
</span><span>catch</span>(<span>Exception</span> <span>$e</span><span>)
{
    </span><span>if</span>(<span>$e</span>->getCode() == 999<span>)
    {
        </span><span>#</span><span>进行一些操作</span>
<span>    }
    </span><span>else</span><span>
    {
        </span><span>throw</span> <span>$e</span><span>;
        
    }
}</span>