捕获JSON 解析错误

$json = <<<JSON
{
    "origin":"Delhi",
    "destination":"London",
    "passengers":
    [
        {
            "name":"Mr. Perry Mason",
            "type":"Adult",
            "age":28
        },
        {
            "name":"Miss Irene Adler",
            "type":"Adult",
            "age":25
        }
    ],
    "travelDate":"17-Dec-2010"
}
JSON;
$objJson = json_decode($json);
switch(json_last_error())
{
    case JSON_ERROR_NONE:
        echo 'Travel date is:' . $objJson->travelDate;
    break;
    case JSON_ERROR_SYNTAX:
        echo 'Incorrect json : Please check your json syntax';
    break;
    case JSON_ERROR_CTRL_CHAR:
        echo 'Control character error';
    break;
    case JSON_ERROR_DEPTH:
        echo 'The json string has exceeded maximum allowed stack depth';
    break;
}