China's factory activity expanded for a second straight month in April, as manufacturers cranked up production to ship goods early to buyers worried the Iran war will further inflate costs, sending new export orders to their strongest level in two years. But the escalating Middle East conflict is laying bare risks in the $20 trillion economy's production-led growth model, with higher energy prices likely to deter fresh orders once stockpiling fades, even as Chinese exporters enjoy a short-lived boost.