Why FrameWork is so important
Although Android Framework development is relatively low-level and has a narrow circle, if you can master some principles, you can learn by analogy and develop to the application layer. Next, let's take a look at how important Framework knowledge is. With a few chestnuts, you may be able to understand.
Things like frame drop monitoring, function instrumentation, slow function detection, ANR monitoring, and startup monitoring all require a deep understanding of the Framework to know how to monitor, what mechanism to use for monitoring, where to insert function instrumentation, and reflection Which class, which method, which property should be called for reflection...
At present, the app development of large companies must design the architecture based on the ideas of modularization, layering, componentization, and control, and all of this is based on the implementation of the underlying principles of the Android Framework system framework. In the recruitment requirements of major factories, it is logical that FrameWork experience will be required.
The Android system is divided into 4 layers:
1. Application
2. FrameWork layer
3. Library layer + Android Runtime
4. Linux Kernel
Among them, Framework is on the second layer. It abstracts some basic services or services related to devices and makes API calls to Application applications. Here is the lowest level java code in Android. It calls c and c++ (Library) through JNI to deal with the device, and finally calls the Linux kernel.
AndroidFramework mainly includes the following modules:
- ActivityManagerService—This is an Activity manager responsible for managing all Acti