计算机专业毕业论文外文文献翻译 安卓应用基础.doc

毕业论文 外文及翻译 原 文 题 目 Android Application Fundamentals 学院专业班级 信息与控制工程学院 计算机08-1 学 生 姓 名 性别 指 导 教 师 职称 年 月 日 外文及翻译 英语原文 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. Each process has its own virtual machine (VM), so an applications code runs in isolation from other applications. By default, every application runs in its own Linux process. Android starts the process when any of the applications components need to be executed, then shuts down the process when its no longer needed or when the system must recover memory for other applications. In this way, the Android system implements the?principle of least privilege. That is, each application, by default, has access only to the components that it requires to do its work and no more. This creates a very secure environment in which an application cannot access parts of the system for which it is not given permission. However, there are ways for an application to share data with other applications and for an application to access system services: Its possible to arrange for two applications to share the same Linux user ID, in which case the