php - 获取触发 "Failed calling MyClass::jsonSerialize()"异常的异常

Question

这个例子:

<?php

    class MyCustomException extends Exception {

    }

    class MyClass implements JsonSerializable {

        function jsonSerialize() 
        {
            throw new MyCustomException('For some reason, something fails here');
        }

    }

    try {
        json_encode(new MyClass);
    } catch(Exception $e) {
        print $e->getMessage() . "\n";
    }

将输出:调用 MyClass::jsonSerialize() 失败。如何得到MyCustomException，这就是这个错误的真正原因？

Answer 1

答案在 Exception 类的 previous 属性中。要获得原始异常，try - catch block 应该稍微改变一下:

try {
    json_encode(new MyClass);
} catch (Exception $e) {
    if ($e->getPrevious()) {
        print $e->getPrevious()->getMessage() . "\n";
    } else {
        print $e->getMessage() . "\n";
    }
}

这个异常也可以重新抛出:

try {
    json_encode(new MyClass);
} catch (Exception $e) {
    if ($e->getPrevious()) {
        throw $e->getPrevious();
    } else {
        throw $e;
    }
}