-3.Android程序设计之系统架构深入浅出.pptVIP

* * * * * * * * * * * * Android 长征开始--系统架构分析 Android System Analysis * Android系统体系概述 活动 用户界面部件通常对应一个屏幕 意向接收 设置并回应提示或状态改变，并激活应用程序 服务 没有前端界面的后台任务 内容提供 应用程序可以共享数据 应用程序构建模块 Android框架 JNI JAVA C/汇编 1. 最低层是linux kernel，主要负责内存管理、进程调度等系统管理以及终端的硬件驱动。Binder driver，google为android设计的一个增强系统的进程间通信能力的模块。 2. Kernel的上一层是libraries，包含了核心库、第三方库和android虚拟机。android并没有直接采用传统的j2se或j2me的java虚拟机，而是自己建立了一个称为dalvik的虚拟机，号称更节省字节码的空间，性能更好。但这也成为了google与sun关于java版权争议点。 3. Framework是android为应用开发者设计的一套软件框架，提供了丰富的api和一些现成的开发元素。Framework是采用java语言实现的。在NDK出来之前，android应用开发者基本上只能用java来开发应用。 Android使用JNI连接了libraries和framework。 4. Application就是在framework的基础上开发的各种应用。 * 本地库 Bionic Libc 函数库(Funtion Libraries) 本地服务(Native Servers) 硬件抽象库(Hardware Abstraction Libraries) Libraries Android includes a set of C/C++ libraries used by various components of the Android system. These capabilities are exposed to developers through the Android application framework. Some of the core libraries are listed below: System C library - a BSD-derived implementation of the standard C system library (libc), tuned for embedded Linux-based devices Media Libraries - based on PacketVideos OpenCORE; the libraries support playback and recording of many popular audio and video formats, as well as static image files, including MPEG4, H.264, MP3, AAC, AMR, JPG, and PNG Surface Manager - manages access to the display subsystem and seamlessly composites 2D and 3D graphic layers from multiple applications LibWebCore - a modern web browser engine which powers both the Android browser and an embeddable web view SGL - the underlying 2D graphics engine 3D libraries - an implementation based on OpenGL ES 1.0 APIs; the libraries use either hardware 3D acceleration (where available) or the included, highly optimized 3D software rasterizer FreeType - bitmap and vector font rendering SQLite - a powerful and lightweight relational database engine available to all applications * SQLite 轻量级事务数据存储 多数平台数据存储的后端 * Dalvik 虚拟机 完全为Android定制的虚拟机，基于QEMU 提供应用程序可