php中的Exception

如果定制的EXCEPTION搞定了，默认的，就自然不在话下罗。

直接上最曲折的过程。

InvalidIdException.php

<?php

namespace Bookstore\Exceptions;

use Exception;

class InvalidIdException extends Exception {
    public function __construct($message = null) {
        $message = $message ?: 'Invalid id provided.';
        parent::__construct($message);
    }
}
?>

ExceedeMaxAllowedException.php

<?php

namespace Bookstore\Exceptions;

use Exception;

//从默认的Exception继承
class ExceedeMaxAllowedException extends Exception {
    //只有构造函数
    public function __construct($message = null) {
        //PHP新语法,如果$message为空,则取默认值
        $message = $message ?: 'Exceeded max allowed.';
        //调用父类构造函数,传递消息
        parent::__construct($message);
    }
}

?>

Unique.php

<?php
namespace Bookstore\Utils;

use Bookstore\Exceptions\InvalidIdException;
use Bookstore\Exceptions\ExceedeMaxAllowedException;

require_once __DIR__ . '/InvalidIdException.php';
require_once __DIR__ . '/ExceedeMaxAllowedException.php';

trait Unique {
    //static静态属性,类似于其它语言的类变量
    private static $lastId = 0;
    //protected保护属性,仅允许继承类访问
    protected $id;

    public function setId(int $id) {
        if ($id < 0) {
            //抛出自定义异常
            throw new InvalidIdException('Id cannot be negative.');
        }
        //内置函数判断id是否为空,比$id == null要逼格好点
        if (empty($id)) {
            //注意区分$this-和self::$的语法
            $this->id = ++self::$lastId;
        } else {
            $this->id = $id;
            if ($id > self::$lastId) {
                self::$lastId = $id;
            }
        }
        if ($this->id > 50) {
            //抛出自定义异常
            throw new ExceedeMaxAllowedException('Max number of users is 50.');
        }
    }

    public function getId():int {
        return $this->id;
    }

    //静态方法
    public static function getLastId():int {
        return self::$lastId;
    }

}

?>

test.php

function createBasicCustomer($id) {
    //捕获异常
    try {
        echo "\nTrying to create a new customer.<br/>";
        return new Basic($id, "name", "suname", "email");
    } catch (InvalidIdException $e) {
        echo 'You cannot provide a negative id:'
            . $e->getMessage() . "<br/>";
    } catch (ExceedeMaxAllowedException $e) {
        echo 'No more customer are allowed:'
            . $e->getMessage() . "<br/>";
    } catch (Exception $e) {
        echo 'Unkown exception:'
            . $e->getMessage() . "<br/>";
    } finally {
        echo "End of function.<br/>";
    }
}

$basic = createBasicCustomer(1);
$basic = createBasicCustomer(-1);
$basic = createBasicCustomer(55);

输出：

Trying to create a new customer.
End of function.
Trying to create a new customer.
You cannot provide a negative id:Id cannot be negative.
End of function.
Trying to create a new customer.
No more customer are allowed:Max number of users is 50.
End of function.