安卓应用基础

安卓应用基础(中文5500字,英文3800字)
    Android应用程序是用JAVA编程语言编写的，Android的SDK工具编译成代码和数据和资源文件放到一个Android的包，一个归档文件档案资源的.apk后缀，所有的在一个单一的代码.apk文件被认为是一个应用程序，是Android的文件，供电设备来安装应用程序。
    一旦安装在设备上，每个Android应用程序的生命在它自己的安全沙箱：
而Android操作系统是一个多用户LINUX系统中，每个应用程序是一个不同的用户。
默认情况下，每个应用程序的系统分配一个唯一的LINUX用户ID（该ID仅用于由系统是未知的应用程序），系统设置所有的应用程序中的文件权限，以便只有用户ID分配给该应用程序可以访问它们。

Android Application Fundamentals  
    Android applications are written in the JAVA programming language. The Android SDK tools compile the code—along with any data and resource files—into an Android package, an archive file with an .apk suffix. All the code in a single .apk file is considered to be one application and is the file that Android-powered devices use to install the application.
    Once installed on a device, each Android application lives in its own security sandbox:
The Android operating system is a multi-user LINUX system in which each application is a different user.
By default, the system assigns each application a unique LINUX user ID (the ID is used only by the system and is unknown to the application). The system sets permissions for all the files in an application so that only the user ID assigned to that application can access them.