Exception::getPrevious

(PHP 5 >= 5.3.0, PHP 7)

返回异常链中的前一个异常

说明

finalpublicException::getPrevious(void): Throwable

返回异常链中的前一个异常（Exception::__construct()方法的第三个参数）。

参数

此函数没有参数。

返回值

返回异常链中的前一个异常Throwable，否则返回NULL。

更新日志

范例

Example #1 Exception::getPrevious()示例

追踪异常，并循环打印。

<?php
class MyCustomException extends Exception {}
function doStuff() {
    try {
        throw new InvalidArgumentException("You are doing it wrong!", 112);
    } catch(Exception $e) {
        throw new MyCustomException("Something happend", 911, $e);
    }
}
try {
    doStuff();
} catch(Exception $e) {
    do {
        printf("%s:%d %s (%d) [%s]\n", $e->getFile(), $e->getLine(), $e->getMessage(), $e->getCode(), get_class($e));
    } while($e = $e->getPrevious());
}
?>

以上例程的输出类似于：

/home/bjori/ex.php:8 Something happend (911) [MyCustomException]
/home/bjori/ex.php:6 You are doing it wrong! (112) [InvalidArgumentException]

参见

• Throwable::getPrevious()

/**
   * Gets sequential array of all previously-chained errors
   * 
   * @param Throwable $error
   * 
   * @return Throwable[]
   */
  function getChain(Throwable $error) : array
  {
    $chain = [];
    do {
      $chain[] = $error;
    } while ($error = $error->getPrevious());
    return $chain;
  }

May be I am late (5.2 is not supported). But if you want use the functionality of "previous Exception" in PHP < 5.3 or write compatible code, you can use next way as below.
<?php
abstract class App_Exception_PreviousNativeAbstract extends Exception {
  public static $printPrevious = true;
  public function __toString() {
    $result  = array();
    $result[] = sprintf("Exception '%s' with message '(%s) %s' in %s:%d", get_class($this), $this->code, $this->message, $this->file, $this->line);
    $result[] = '---[Stack trace]:';
    $result[] = $this->getTraceAsString();
    if (self::$printPrevious) {
      $previous = $this->getPrevious();
      if ($previous) {
        do {
          $result[] = '---[Previous exception]:';
          $result[] = sprintf("Exception '%s' with message '(%s) %s' in %s:%d", get_class($previous), $previous->getCode(), $previous->getMessage(), $previous->getFile(), $previous->getLine());
          $result[] = '---[Stack trace]:';
          $result[] = $previous->getTraceAsString();
        } while(method_exists($previous, 'getPrevious') && ($previous = $previous->getPrevious()));
      }
    }
    return implode("\r\n", $result);
  }
}
abstract class App_Exception_PreviousLegacyAbstract extends App_Exception_PreviousNativeAbstract {
  protected $previous;
  public function __construct($message, $code = 0, Exception $previous = null) {
    $this->previous = $previous;
    parent::__construct($message, $code);
  }
  public function getPrevious() {
    return $this->previous;
  }
}
if (version_compare(PHP_VERSION, '5.3.0', '>=')) {
  abstract class App_Exception_PreviousAbstract extends App_Exception_PreviousNativeAbstract {}
}
else {
  abstract class App_Exception_PreviousAbstract extends App_Exception_PreviousLegacyAbstract {}
}
class App_Exception extends App_Exception_PreviousAbstract {
  public function __construct($message, $code = 0, Exception $previous = null) {
    parent::__construct($message, 0, $previous);
  }
}
// Example:
try {
  // ...
  throw new Exception('Exception mesage');
  // ...
} catch (Exception $e) {
  throw new App_Exception('App exception mesage', 0, $e);
}
?>