Software developers often face challenges in reusing open source frameworks due to several factors such as the framework complexity and lack of proper documentation. In this paper, we propose a code-search-engine-based approach that detects hotspots in a given framework by mining code examples gathered from open source repositories available on the web; these hotspots are API classes and methods that are frequently reused. Hotspots can serve as starting points for developers in understanding and reusing the given framework. Our approach also detects coldspots, which are API classes and methods that are rarely used. Coldspots serve as caveats for developers as there can be difficulties in finding relevant code examples and are generally less exercised compared to hotspots. We developed a tool, called SpotWeb, for frameworks or libraries written in Java and used our tool to detect hotspots and coldspots of eight widely used open source frameworks. We show the utility of our detected hotspots by comparing these hotspots with the API classes reused by a real application and compare our results with the results of a previous related approach.