Opportunistic networks are sparse wireless networks where most of the time there does not exist complete path from the source to the destination. The messages can be forwarded to destination ultimately in the manner of asynchronous transmission which relies on the contact opportunities between nodes in opportunistic networks. This characteristics of opportunistic networks can greatly extend the space-time metric of information collection and processing. Although opportunistic network often shows large delay, it doesnt mean that it is not necessary to implement quality assurance. For examples, electronic notice in campus networks and short-term weather information in large national parks must be forwarded with specific delay. On the other hand, as the access networks, configuration and forecast for QoS are also necessary in order to provide acceptable service (such as e-mail) in opportunistic networks. Hence opportunistic networks must provide acceptable and resilient service in the face of challenging environments. According to the shortcoming of traditional spray routing in dynamic opportunistic networks, a class of adaptive spray mechanisms are proposed in this paper. Adaptive spray mechanisms use relay nodes to make spray decisions in order to apperceive and react to the change of network conditions exquisitely, and are least-cost delay-bounded routing protocols under specific spray mechanisms. Theoretic analysis of adaptive spray routing at aspects of routing cost, copy redundancy and expected delay are also given. Simulation results show that adaptive spray mechanisms show prominent superiority in routing cost, adaptability and expansibility, and are a class of correct and efficient delay-bounded opportunistic networks routing mechanisms.