BEIJING — Capping 10 careful years at the helm of the Communist Party, China’s top leader, Hu Jintao, boasted on Thursday of successes during his tenure while issuing a blunt warning against unrest and political reform.

Hu, 69, is to step down as the party’s general secretary next week, handing power to his designated successor, Xi Jinping. His speech at the opening of the Communist Party’s 18th congress was likely to be his last major address — a chance to write his own eulogy while also setting the course for Xi.