PHP异常转移

/**
PHP之异常转移
分析：
 老师用电脑上课
   问题领域涉及三个对象
   学校 ,老师，电脑

***/
//电脑异常
class ComputerLanPiException  extends   Exception {
         
         Public   function  __Construct($msg) {
                       parent ::  __Construct($msg);
         }

}
//电脑异常
class ComputerMaoYanException  extends   Exception {
         
         Public   function  __Construct($msg) {
                      parent ::  __Construct($msg);
         }

}



/***学校问题主要管理学校的课程进度的问题异常**/
class   NoPlanException   extends  Exception {
         
        Public   function  __Construct($msg) {
                      parent ::  __Construct($msg);
         }
 
}

Class  Computer {
      private   $state = 2;  //电脑 状态

      Public  function  run() {  //若是是java的话那么 他会对run函数进行总体抛出  throw  xx ,xx
            
          if($this->state == 1) {          
               
                throw   new ComputerLanPiException('电脑蓝屏了');
          
          }

          if($this->state ==2) {

                throw   new  ComputerMaoYanException('电脑冒烟了');
          
          }

          echo  '电脑运行了...<br/>';
      }
         
         //重启电脑
      Public  function  reset() {
            echo  '电脑重启了<br/>';
            $this->state = 0 ;
      }

}

Class   Teacher {

     Private   $names;  //老师的名字
     Private   $comp;  //老师的电脑


     Public   function  __Construct($name,$comp) {
                   $this->names = $name;
                   $this->comp = $comp;
     }

     Public   function   Prelect () {
           try{
             
                      $this->comp->run();   //先运行电脑
                       echo $this->names.'讲课者';  //老师名字 

                     } catch (ComputerLanPiException  $e) {  //若是出现蓝屏的异常咱们就直接重启
                
                        $this->comp->reset();   //重启
                        $this->Prelect() ;  //开始讲课对吧
                        echo  '<hr/>';
                        echo  $e->__toString(); //把对象转换为字符串 

                      } catch (ComputerMaoYanException  $e){  //电脑坏了怎么办法
                         
                           echo  '电脑冒烟了..<br/>';
                          $this->test();            

                           /****************异常转移*********************/
                          //echo  '<hr/>';    //异常转换
                          //throw  $e;   //继续向上抛出异常 这样抛不合理 由于 学习这块也没办法去解决这状况电脑换了的状况

                           //echo  $e->__toString(); //把对象转换为字符串 
                          //java中直接 throw  e;
                          //throw  new  ComputerMaoYanException('电脑冒烟了');  //继续抛出异常
                           $msg ='课程没法完成  缘由:'.$e->__toString();  //把对象转换成字符串
                            //异常转换
                            throw  new   NoPlanException ($msg);  //抛出课程进度没法完成的异常//这叫异常转换
                        /****************异常转移*********************/
                   }
                  
     }

     Private  function   test() {
     
                 echo  '作你们练习';

     }



}



class  ExceptionsTest {
 
      /**自定义主函数*/
     Public   Static  function  Main(){
                    $comp = new Computer();
                    $t = new Teacher("任老师",$comp);  //初始化老师
                    try{
                          $t->Prelect(); //调用老师讲课        
                        
                     } catch(NoPlanException $e) {  //这叫异常转换
                         echo  '<hr/>';
                          echo  $e->getMessage();
                          echo  '<hr/>';
                          echo ' 学校立刻换人了....';
                      
                      /***下面就是换人的****/
                     $comp = new Computer();
                     $comp->reset();
                     $t = new Teacher("王老师",$comp);  //初始化老师
                     $t->Prelect(); //调用老师讲课        
        
                    }
                
            
     }

}

header("Content-Type:text/html;charset=utf-8;");
ExceptionsTest :: Main();  //入口