php抛出异常与捕捉特定类型的异常详解

  <?php
  header("content-type:text/html; charset=utf-8");
  /**
  * 包裹重量异常
  */
  class HeavyParcelException extends Exception {}
  
  /**
  * 包裹类
 */
 class Parcel {
 
   /**
   * 包裹寄送目的地地址
   */
   public $address;
 
   /**
   * 包裹重量
   */
   public $weight;
 }
 
 /**
 * 派送员
 */
 class Courier {
  
   /** 
   * 运送
   */
   public function ship(Parcel $parcel) {
     //check we have an address
     //如果包裹的目的地为空
     if(empty($parcel->address)) {
       throw new Exception(&#39;address not Specified(未填写地址)!&#39;);
     } 
 
     //check the weight
     //如果重量超过5
     if($parcel->weight > 5) {
            throw new HeavyParcelException(&#39;Parcel exceeds courier limit(包裹超过运送上限)!&#39;);
     } 
 
     //otherwise we&#39;re coll
     return true;
   }
 }
 
 $myCourier = new Courier();
 $parcel = new Parcel();
 //add the address if we have it 为了测试这里不填写地址
 $parcel->weight = 7;
 try {
   $myCourier->ship($parcel);
   echo "parcel shipped";
 } catch (HeavyParcelException $e) {//捕获HeavyParcelException 不写这个异常的类型名字，就跑到普通Exception抛出去了
   echo "Parcel weight error(重量错误): " . $e->getMessage();
   //redirect them to choose another courier
 } catch (Exception $e) {
   echo "Someting went wrong(地址错误): " . $e->getMessage();
   //exit so we don&#39;t try to proceed any further
   exit;
 }
 echo &#39;<br/>&#39;;
 $a = 123;
 echo $a;