毕业设计外文资料翻译-安卓：程序员指南

1、毕业设计外文资料翻译学 院： 专业班级： 学生姓名： 学 号： 指导教师： 外文出处： Android: A Programmers Guide 附 件：1.外文资料翻译译文； 2.外文原文 指导教师评语：该同学的翻译有一定的准确率，语句顺畅，工作量充分，格式排版符合学校要求。同意翻译通过！签名： 2015 年10月 14日1外文资料翻译译文安卓：程序员指南1 什么是 Android?1.1关键技术&概念嵌入式设备编程项目历史解释开放手机联盟第一次观看Android主屏幕能够说，传统的桌面应用程序开发者已经很受宠了。这不是说传统桌面应用程序开发比其他形式的开发更简单。然而，作为一个传统桌面应用

2、程序开发者，我们已经有创建所有我们能够想象的任何一种应用程序的能力。包括我在内，因为我以前就做过桌面项目开发。一方面，我们已经有能力去和桌面操作系统互动，已经使桌面编程开发更易接受，这样的互动是和任何底层的硬件的互动。相当自由（或者至少有很小的例外）。这种自由、独立地编程，已经不再是那些敢于冒险跳进手机开发大潮少量开发者能够获得的。注意：在这个讨论中我提及到了两种不同的开发者：传统桌面应用程序开发者，他们几乎用所有的编程语言来工作，他们的最终产品、应用程序被构建成能运行在任何一种桌面操作系统上；Android开发者（Java开发者），为Android平台开发。这不是有意图说哪一种开发者在某种意

3、义上比另一种更好或者更坏。这个讨论意图在于：桌面操作系统环境和移动操作系统环境Android的开发形式和开发工具的比较。1.2简短的嵌入式设备开发历史很长一段时间，手机开发者构成了一个认作是嵌入式设备开发者的稍微大点的派别。理解成一个小的具有魅力的桌面家族成员-后来的网络Web-开发，嵌入式设备开发代表性地操作系统特色，因为嵌入式设备制造业在特色支持方面恶名昭彰地吝啬。嵌入式设备制造厂商典型地需要封闭地保护他们硬件的机密，因此，当嵌入式设备开发者试着去与特殊的设备互动时，嵌入式设备制造厂商给他们很少的函数库去调用。嵌入式设备不同于桌面系统，嵌入式设备是一个典型的“片上计算机”。例如：考虑你的标

4、准电视机的远程控制。它不是真正看上去像一个无法实现的复杂技术。当任何一个按钮按下，芯片以一种方法解释信号（已经编程嵌入到设备中）。这允许设备从输入设备（键盘）知道用户期望干什么，和如何对这些命令响应（例如，打开电视机）。这是一个来自嵌入式设备的编程例子。然而，信或不信，诸如这些简单的设备被明确涉及到早期手机设备和开发的根源。大多数嵌入式设备运行（在一些情况仍然运行）在专有的操作系统上。选择创建一个专有的操作系统而不是使用任何消费者系统的理由是：这是一个产品正真必需的。简单的设备不需要很耐用、完善的操作系统。作为一种设备产品的发展，大约2年前左右，许多复杂的嵌入式设备，例如早期的PDAs，家庭安

5、全系统，和GPSs，被移植到标准化的操作系统平台上。小体积的操作系统如Linux，或甚至嵌入式版本的MicrosoftWindows，已经是在许多嵌入式设备上很流行了。围绕这个时间段的设备发展，手机从其他的嵌入式设备分支成他们自己的路线。当你查看他们的业绩时，这个分支显得很明显。起初，当运行专有的软件（被制造厂商拥有和控制，几乎也总是被考虑是“封闭”系统）时，手机就已经在终端设备的范围内。制造厂商使用专有的操作系统更加不必要。这是因为手机制造商代表性的使用完全在内部开发出的硬件。或至少硬件是为运行手机设备特别开发出来的，结果，这些硬件、专有系统不是开发地可获得的，空架的软件包，或者解答（这些都

6、是能够确切与他们硬件互动的）。自制造商想更可靠地保护他们的硬件交易机密（通过允许接近设备软件水平可以显露出来），通常的实践是（在多数情况下仍然是）通过完全专用的和封闭的软件来运行他们的设备。接下来就是，任何想为手机开发能够在上面运行的应用程序的人不得不去揭秘专有系统环境。解决方法是直接向制造商购买昂贵的开发工具。这孤立了很多“业余爱好”的开发者们。注意：一种成长的业余爱好开发者文化已经拥抱着手机应用程序开发。“业余爱好者”队伍事实涉及到了那些具有代表性的、不是为手机开发公司工作的开发者和普遍地小生产，利用他们自己时间开发产品的人。其他的，更多强制的“必需品”是硬件制造商对于“内存对照需求”困境

7、的解答（这使天天进行手机开发的开发者难以入手）。直到最近，手机不是比实现多一点点，接收电话，跟踪你的联系，并且可能的发送和接收文本短信；当今他们不是真正的“瑞士军刀”技术。甚至迟到2002年，带有照相机的手机在消费者的手上一般的也没有见到。到1997年，小应用程序例如计算器和游戏（俄罗斯方块）缓慢地在手机上出现他们的发展路线，但是这些无法实现的功能仍然是电话拨号程序本身。手机还没有成为今天它们的多样的，多功能的个人工具。1997年，手机制造商完全没有意识到消费者需求是所有功能集聚一个设备上。设备的内存缺乏，存储能力是一个更大的要去克服的障碍。更多的人可能已经想过他们的设备变成聚集所有功能为一身

8、的工具，但是制造商仍然不得不解决内存障碍。为了使问题简单，这使得任何设备上让内存去存储和运行应用程序，包括手机。手机，作为一种设备，直到最近都还没有使手机容易包含额外程序的大量内存。在最近两年里，内存价格已经达到很低的水平了。设备制造商现在有能力以更低的价格包含更多的内存。现在很多手机拥有比1990世纪中期普通PC机更标准的内存。因此，现在我们有了需要、内存，我们可以深入，并且在世界范围里为手机开发酷的应用程序。设备制造商仍然封闭地保护运行在他们设备上的操作系统。而一些对这一点已经开放，他们允许一些以Java为基础的应用程序在手机上的小环境里运行，许多的都不允许这样做。甚至某些不允许运行一些J

9、ava应用程序的系统不允许接近标准桌面开发者去拥有的核心系统。1.3开放手机联盟和 Android在2007年11月，当Google，在开放手机联盟下，发布Android，这个对于应用程序开发者的障碍开始消失。开放手机联盟是一个硬件和软件开发者组织，它包括 Google 、NTT DoCoMo ，Sprint Nextel， 和 HTC，它的目标是创建一个更开放的手机环境。在开放手机联盟组织下发布的第一个产品是Android-移动设备操作系统。（获得更多关于开放手机联盟的信息，登陆）和Android发行一起，Google开发了可获得的主要开发工具和指南去帮助要成为新系统开发者的人。帮助文档、平

10、台软件开发包（SDK）甚至在Google的Android网站上能被找到的一个开发者社区，/android.这个网站应该是你的入门点，我十分鼓励你去访问该网站。注意：Google，为促进新的Android操作系统，甚至开始了举办了一个1000万奖金的竞赛，寻求新的、令人兴奋地Android应用程序。而运行在Linux、Windows、甚至PalmOS上的手机能轻易找到，到写这书为止，没有硬件平台被宣布专门为Android所运行HTC、LG电子、Motorola和Samsung都是开放手机联盟的成员，在Android已经被发布之下，我们只希望他们为Android-based设备在未来有计划实行。它

11、在2007年11月发行，这系统本身仍然只是一个测试版软件。这对于开发者是一个好消息，因为它给我们一个展望未来系统珍贵的进步发展和一个开始开发将会很快在被发布的硬件上运行的应用程序的机会。注意：这个策略清楚地给开放手机联盟一个大优势超过别的手机操作系统开发者，因为对于第一个发布的运行Android的设备将会有无数的应用程序可以直接获得。Android作为一个系统,是一个运行在Linux2.6内核上的基于Java的操作系统.这个系统是非常轻量级的,并且功能丰富，拥有Android应用程序是用Java开发的，能够十分简单的装入新的平台。如果你还没有下载Java或者不确信需要哪个版本，我在第二章节详述

12、安装开发环境。Android的其他特色包括加速3D绘图引擎（依赖于硬件支持），SQLite强力支持的数据库，和一个综合完整的Web浏览器。如果你熟练Java编程或者是一个任何种类的OOP开发者，你可能用过用户界面（UI）开发，那是UI放置（直接在项目源码中运用的）。Android能识别和允许为项目的UI做开发，也支持更新的，基于XML的UI编排设计。XMLUI编排设计对于一般桌面开发者是一个相当新的概念。在本书支持的章节里我将涵盖XMLUILayout和项目的UI开发。Android一个最令人兴奋和注目的特色是它的架构，三部分运用程序-包括“home-grown”当这些和内核系统绑定，可带有同

13、样的系统优先权执行。这是和大多系统一个主要的不同，它给了嵌入式系统应用程序一个比进程优先级（从第三方开发者创建的应用程序获得）更大的执行权。每一个应用程序在它自己的进程里使用一个很轻量级的虚拟机执行。除了我们能够获得用来开发的很大量的SDK和良好的架构库，对于Android开发者最令人兴奋的特色是我们现在允许进入任何操作系统。换句话说，如果你要创建一个拨电话的应用程序，你可接近电话拨号程序，如果你想创建一个利用电话的内在GPS的应用程序（如果配备），你可以接近它。对于开发者创建动态的和令人感兴趣的应用程序的可能性现在是宽阔开放了。在这些特色中最顶级的是从Android网站可获得的平衡，Goog

14、le已经投放一些它自己的特色。Android应用程序开发者将能够去把自己的应用程序连接到Google提供的已经存在的程序（例如GoogleMaps、Google搜索）上。假设你想写一个获取一个打进电话的发出地的Google地图，或者你想能够存储你联系的一般搜索结果；利用Android可能性的大门开放。将开始你的Android开发之旅。你将学到怎样和为什么使用特殊的开发环境或综合完整的开发环境（IDE），并且你将会下载和安装JavaIDEEclipse。2应用：你好世界2.1关键技能和概念创造新的Android项目工作的意见使用TextView修改main.xml文件在Android模拟器运行应

15、用程序在本章中，您将创建您的第一个安卓项目。本章探讨了应用程序的构建过程从开始到结束。我将告诉你如何创建一个Android项目检测PSE，代码添加到初始文件，在Android模拟器运行完成后的应用程序。由此产生的应用程序将是运行在安卓环境一个功能齐全的程序。实际上，当你在这一章中时，你将会创造一个以上的机器人活动。计算机编程的传统决定了你的第一个应用程序是典型的你好世界！因此，在第一节中，您将创建一个标准的世界！应用程序只是一个空白背景和“你好世界”！文本。然后，为了使你了解语言，下一节详细解释了由安卓自动创建的文件应用。您将创建两个迭代的活动，每个使用不同的技术在屏幕上显示信息的技巧。您还将

16、创建一个世界上的2个不同的版本！应用程序将显示一个图像，提供“你好世界”！信息。注意：你会经常看到“应用程序”和“活动”交替使用。两者的区别在于，应用程序可以由多个活动组成，但一个应用程序必须至少有一个活动。每一个“窗口”或您的应用程序的屏幕是一个单独的活动。因此，如果你创建一个相当简单的应用程序，只有一个屏幕的数据（如世界你好！在本章中的应用程序，这将是一个活动。在未来的章节中，你将创建多个活动的应用程序。为了确保你能对Android编程有整体的了解，在第6章，您将创建这些应用程序的Android SDK中微软视窗和系统环境。换句话说，本章涵盖了在Eclipse的创作过程中，第6章涵盖了使用

17、命令行工具的创建过程。因此，在继续之前，你应该检查你的Eclipse环境是否正确配置。审查设置Android SDK的路径语句按照第3章中的步骤。你也应该确保在你的路径语句的JRE是正确的。提示：如果你在试图与任何一方面工作时，都有与之相关的问题命令行示例，在第2和第3章中尝试参考配置步骤；看看Android SDK文档。2.2创建您的第一个安卓项目在Eclipse要启动你的第一个项目，打开Eclipse。当你第一次打开Eclipse，它打开一个空的开发环境（见图5-1），这是你要开始的地方。你的第一任务是为应用程序设置和命名工作区。选择文件|新| Android项目，将推出新的Android

18、项目向导。小心不要从新菜单中选择项目。而Android应用程序是用Java写的，和你所做的一切都是你的Java开发项目，此选项将创建一个标准的Java一个应用程序。选择安卓项目使您能够创建安卓特定应用程序。如果您不知道安卓项目的选项，这说明该安卓插件是没有完全正确安装。2.3新安卓项目向导为您创建了2件事加壳程序，关系到Android SDK，使用android.jar文件，并联系项目为Android模拟器。这允许您使用所有的安卓库和软件包来使用代码，而且还可以让你在适当的环境中调试应用程序。你的新项目的第一个外壳文件。这些外壳文件包含了一些重要的应用程序块，您将在其中构建程序。在许多相同的方

19、式创建一个微软。网络应用程序在视觉工作室生成一些窗口在您的文件创建的程序代码，使用的安卓项目向导在Eclipse产生您的初始程序文件。此外，新的Android项目向导包含几个选项，下面，你必须设置你的Android项目启动。为项目名称字段，为了这个例子，使用该示例E题helloworldtext。这个名字足以区分这个你好世界！本章将创建其他项目。在内容区域，保留默认选择：创建新的项目在工作区的无线按钮应选择和使用默认位置检查框检查。这将允许在默认的工作空间方向的Eclipse创建您的项目。保持默认选项的优点是，您的项目被保存在一个中心位置，这使得管理和查找这些项目很容易。例如，如果你是在基于U

20、NIX的环境中工作，这条路指向你的$HOME目录。如果你在微软视窗环境中工作，工作区路径将为：/用户/ /工作区，如上图所示。然而，由于任何数量的原因，你可能想要取消使用默认位置”复选框，为您的项目选择一个不同的位置。如果你想选择一个位置，你可以在这里单独从其他安卓项目指定一个不同的位置。例如，你可能想要保留你在这本书中创建的项目，在未来的项目中创造出不同的位置。如果是的话，请简单地重写位置选项来指定该项目区的自定义位置。外文原文 Android: A Programmers Guide 1 What Is Android1.1 Key Skills & Concepts History of

21、 embedded device programming Explanation of Open Handset Alliance First look at the Android home screenIt can be said that, for a while, traditional desktop application developers have beenspoiled. This is not to say that traditional desktop application development is easier thanother forms of devel

22、opment. However, as traditional desktop application developers, wehave had the ability to create almost any kind of application we can imagine. I amincluding myself in this grouping because I got my start in desktop programming.One aspect that has made desktop programming more accessible is that we

23、have had theability to interact with the desktop operating system, and thus interact with anyunderlying hardware, pretty freely (or at least with minimal exceptions). This kind offreedom to program independently, however, has never really been available to thesmall group of programmers who dared to

24、venture into the murky waters of cell phonedevelopment.NOTE ：I refer to two different kinds of developers in this discussion: traditionaldesktop application developers, who work in almost any language and whose endproduct, applications, are built to run on any “desktop” operating system; and Android

25、developers, Java developers who develop for the Android platform. This is not for thepurposes of saying one is by any means better or worse than the other. Rather, thedistinction is made for purposes of comparing the development styles and tools ofdesktop operating system environments to the mobile

26、operating system environment,1.2 Brief History of Embedded Device ProgrammingFor a long time, cell phone developers comprised a small sect of a slightly largergroup of developers known as embedded device developers. Seen as a less “glamorous”sibling to desktopand later webdevelopment, embedded devic

27、e developmenttypically got the proverbial short end of the stick as far as hardware and operatingsystem features, because embedded device manufacturers were notoriously stingy onfeature support.Embedded device manufacturers typically needed to guard their hardware secretsclosely, so they gave embedd

28、ed device developers few libraries to call when trying tointeract with a specific device. Embedded devices differ from desktops in that anembedded device is typically a “computer on a chip.” For example, consider yourstandard television remote control; it is not really seen as an overwhelming achiev

29、ementof technological complexity. When any button is pressed, a chip interprets the signal ina way that has been programmed into the device. This allows the device to know whatto expect from the input device (key pad), and how to respond to those commands (forexample, turn on the television). This i

30、s a simple form of embedded deviceprogramming. However, believe it or not, simple devices such as these are definitelyrelated to the roots of early cell phone devices and development.Most embedded devices ran (and in some cases still run) proprietary operating systems.The reason for choosing to crea

31、te a proprietary operating system rather than use anyconsumer system was really a product of necessity. Simple devices did not need veryrobust and optimized operating systems.As a product of device evolution, many of the more complex embedded devices,such as early PDAs, household security systems, a

32、nd GPSs, moved to somewhatstandardized operating system platforms about five years ago. Small-footprint operatingsystems such as Linux, or even an embedded version of Microsoft Windows, havebecome more prevalent on many embedded devices. Around this time in deviceevolution, cell phones branched from

33、 other embedded devices onto their own path. Thisbranching is evident when you examine their architecture.Nearly since their inception, cell phones have been fringe devices insofar as they runon proprietary softwaresoftware that is owned and controlled by the manufacturer,and is almost always consid

34、ered to be a “closed” system. The practice of manufacturersusing proprietary operating systems began more out of necessity than any other reason.That is, cell phone manufacturers typically used hardware that was completelydeveloped in-house, or at least hardware that was specifically developed for t

35、hepurposes of running cell phone equipment. As a result, there were no openly available,off-the-shelf software packages or solutions that would reliably interact with theirhardware. Since the manufacturers also wanted to guard very closely their hardwaretrade secrets, some of which could be revealed

36、 by allowing access to the software levelof the device, the common practice was, and in most cases still is, to use completelyproprietary and closed software to run their devices. The downside to this is that anyonewho wanted to develop applications for cell phones needed to have intimate knowledgeo

37、f the proprietary environment within which it was to run. The solution was to purchaseexpensive development tools directly from the manufacturer. This isolated many of the“homebrew” developers.NOTE：A growing culture of homebrew developers has embraced cell phoneapplication development. The term “hom

38、ebrew” refers to the fact that these developerstypically do not work for a cell phone development company and generally producesmall, one-off products on their own time.Another, more compelling “necessity” that kept cell phone development out of thehands of the everyday developer was the hardware ma

39、nufacturers solution to the“memory versus need” dilemma. Until recently, cell phones did little more than executeand receive phone calls, track your contacts, and possibly send and receive short textmessages; not really the “Swiss army knives” of technology they are today. Even as lateas 2002, cell

40、phones with cameras were not commonly found in the hands ofconsumers.By 1997, small applications such as calculators and games (Tetris, for example)crept their way onto cell phones, but the overwhelming function was still that of aphone dialer itself. Cell phones had not yet become the multiuse, mul

41、tifunction personaltools they are today. No one yet saw the need for Internet browsing, MP3 playing, orany of the multitudes of functions we are accustomed to using today. It is possible thatthe cell phone manufacturers of 1997 did not fully perceive the need consumers wouldhave for an all-in-one de

42、vice. However, even if the need was present, a lack of devicememory and storage capacity was an even bigger obstacle to overcome. More peoplemay have wanted their devices to be all-in-one tools, but manufacturers still had toclimb the memory hurdle.To put the problem simply, it takes memory to store

43、 and run applications on anydevice, cell phones included. Cell phones, as a device, until recently did not have theamount of memory available to them that would facilitate the inclusion of “extra”programs. Within the last two years, the price of memory has reached very low levels.Device manufacturer

44、s now have the ability to include more memory at lower prices.Many cell phones now have more standard memory than the average PC had in themid-1990s. So, now that we have the need, and the memory, we can all jump in anddevelop cool applications for cell phones around the world, right? Not exactly.De

45、vice manufacturers still closely guard the operating systems that run on theirdevices. While a few have opened up to the point where they will allow someJava-based applications to run within a small environment on the phone, many do notallow this. Even the systems that do allow some Java apps to run

46、 do not allow the kindof access to the “core” system that standard desktop developers are accustomed tohaving.1.3 Open Handset Alliance and AndroidThis barrier to application development began to crumble in November of 2007 whenGoogle, under the Open Handset Alliance, released Android. The Open Hand

47、setAlliance is a group of hardware and software developers, including Google, NTTDoCoMo, Sprint Nextel, and HTC, whose goal is to create a more open cell phoneenvironment. The first product to be released under the alliance is the mobile deviceoperating system, Android. (For more information about t

48、he Open Handset Alliance,see .)With the release of Android, Google made available a host of development tools andtutorials to aid would-be developers onto the new system. Help files, the platformsoftware development kit (SDK), and even a developers community can be found atGoogles Android website, /

49、android. This site should be yourstarting point, and I highly encourage you to visit the site.NOTE ：Google, in promoting the new Android operating system, even went as faras to create a $10 million contest looking for new and exciting Android applications.While cell phones running Linux, Windows, an

50、d even PalmOS are easy to find, as ofthis writing, no hardware platforms have been announced for Android to run on. HTC,LG Electronics, Motorola, and Samsung are members of the Open Handset Alliance,under which Android has been released, so we can only hope that they have plans for afew Android-base

51、d devices in the near future. With its release in November 2007, thesystem itself is still in a software-only beta. This is good news for developers because itgives us a rare advance look at a future system and a chance to begin developingapplications that will run as soon as the hardware is release

52、d.NOTE：This strategy clearly gives the Open Handset Alliance a big advantage overother cell phone operating system developers, because there could be an uncountablenumber of applications available immediately for the first devices released to runAndroid.Introduction to AndroidAndroid, as a system, i

53、s a Java-based operating system that runs on the Linux 2.6kernel. The system is very lightweight and full featured. Android applications aredeveloped using Java and can be ported rather easily to the new platform. If you havenot yet downloaded Java or are unsure about which version you need, I detai

54、l theinstallation of the development environment in Chapter 2. Other features of Androidinclude an accelerated 3-D graphics engine (based on hardware support), databasesupport powered by SQLite, and an integrated web browser.If you are familiar with Java programming or are an OOP developer of any so

55、rt,you are likely used to programmatic user interface (UI) developmentthat is, UIplacement which is handled directly within the program code. Android, whilerecognizing and allowing for programmatic UI development, also supports the newer,XML-based UI layout. XML UI layout is a fairly new concept to

56、the average desktopdeveloper. I will cover both the XML UI layout and the programmatic UI developmentin the supporting chapters of this book.One of the more exciting and compelling features of Android is that, because of itsarchitecture, third-party applicationsincluding those that are “home grown”a

57、reexecuted with the same system priority as those that are bundled with the core system.This is a major departure from most systems, which give embedded system apps agreater execution priority than the thread priority available to apps created bythird-party developers. Also, each application is exec

58、uted within its own thread using avery lightweight virtual machine.Aside from the very generous SDK and the well-formed libraries that are available to usto develop with, the most exciting feature for Android developers is that we now haveaccess to anything the operating system has access to. In oth

59、er words, if you want tocreate an application that dials the phone, you have access to the phones dialer; if youwant to create an application that utilizes the phones internal GPS (if equipped), youhave access to it. The potential for developers to create dynamic and intriguingapplications is now wi

60、de open.On top of all the features that are available from the Android side of the equation,Google has thrown in some very tantalizing features of its own. Developers of Androidapplications will be able to tie their applications into existing Google offerings such asGoogle Maps and the omnipresent G