Context-aware service apps provide a functionality which is personalized for a user's current situation. A main concern of context-aware mobile apps is a substantial consumption of resources. The excessive drain of resources for context acquisition results in slowing down the execution of other apps and shortening the battery life. Hence, we propose Context Acquisition Platform (CAP) to remedy these problems. CAP runs on mobile devices and provides an abstract layer between context-aware apps and sensors. And, CAP deploys a Context Basket which maintains values of active contexts in advance and offers context values to context-aware apps. With CAP with the Context Basket, the context acquisition is only done by CAP and the context values are shared by multiple context-aware apps, which can substantially reduce the cost to acquire context so that efficiency can be largely increased.