(Android system=Linux kernel Android runtime. The Linux kernel used by the Android system includes some special drivers, such as Logger, Binder, Ashmem, Wakelock, Low MemoryKiller and Alarm. These special Android drivers form the pillar of the Android runtime. Android runtime includes HAL layer, application framework layer and application layer from bottom to top. The HAL layer is primarily designed to circumvent the GPL. It will divide the hardware driver into two parts: the kernel space and the user space, in which the business friendly Apache License is used. The application framework layer mainly includes system services, such as component management services, application installation services, window management services, multimedia services and telecommunications services. The application framework is further divided into C/C and Java. Java code runs on the Dalvik virtual machine and interacts with C/C through JNI methods. The application layer is mainly composed of four components: Activity, Service, BroadcastReceiver and ContentProvider, which are the basis of application development. This PPT starts with a general application architecture and outlines the dedicated driver, HAL, important services, Dalvik, window mechanism and four components of the Android system. As a continuation of the first PPT, this PPT helps to further understand the specific implementation of the Android system. This document includes the following annexes:)
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