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1、*.Android: A Programmers Guide 1 What Is Android1.1 Key Skills & ConceptsHistory of embedded device programmingExplanation of Open Handset AllianceFirst look at the Android home screen It can be said that, for a while, traditional desktop application developers have been spoiled. This is not to say
2、that traditional desktop application development is easier than other forms of development. However, as traditional desktop application developers, we have had the ability to create almost any kind of application we can imagine. I am including myself in this grouping because I got my start in deskto
3、p programming.One aspect that has made desktop programming more accessible is that we have had the ability to interact with the desktop operating system, and thus interact with any underlying hardware, pretty freely (or at least with minimal exceptions). This kind of freedom to program independently
4、, however, has never really been available to the small group of programmers who dared to venture into the murky waters of cell phone development. NOTE ：I refer to two different kinds of developers in this discussion: traditional desktop application developers, who work in almost any language and wh
5、ose end product, applications, are built to run on any “desktop” operating system; and Android developers, Java developers who develop for the Android platform. This is not for the purposes of saying one is by any means better or worse than the other. Rather, the distinction is made for purposes of
6、comparing the development styles and tools of desktop operating system environments to the mobile operating system environment, 1.2 Brief History of Embedded Device Programming For a long time, cell phone developers comprised a small sect of a slightly larger group of developers known as embedded de
7、vice developers. Seen as a less “glamorous” sibling to desktopand later webdevelopment, embedded device development typically got the proverbial short end of the stick as far as hardware and operating system features, because embedded device manufacturers were notoriously stingy on feature support.
8、Embedded device manufacturers typically needed to guard their hardware secrets closely, so they gave embedded device developers few libraries to call when trying to interact with a specific device. Embedded devices differ from desktops in that an embedded device is typically a “computer on a chip.”
9、For example, consider your standard television remote control; it is not really seen as an overwhelming achievement of technological complexity. When any button is pressed, a chip interprets the signal in a way that has been programmed into the device. This allows the device to know what to expect f
10、rom the input device (key pad), and how to respond to those commands (for example, turn on the television). This is a simple form of embedded device programming. However, believe it or not, simple devices such as these are definitely related to the roots of early cell phone devices and development.
11、Most embedded devices ran (and in some cases still run) proprietary operating systems. The reason for choosing to create a proprietary operating system rather than use any consumer system was really a product of necessity. Simple devices did not need very robust and optimized operating systems. As a
12、 product of device evolution, many of the more complex embedded devices, such as early PDAs, household security systems, and GPSs, moved to somewhat standardized operating system platforms about five years ago. Small-footprint operating systems such as Linux, or even an embedded version of Microsoft
13、 Windows, have become more prevalent on many embedded devices. Around this time in device evolution, cell phones branched from other embedded devices onto their own path. This branching is evident when you examine their architecture. Nearly since their inception, cell phones have been fringe devices
14、 insofar as they run on proprietary softwaresoftware that is owned and controlled by the manufacturer, and is almost always considered to be a “closed” system. The practice of manufacturers using proprietary operating systems began more out of necessity than any other reason. That is, cell phone man
15、ufacturers typically used hardware that was completely developed in-house, or at least hardware that was specifically developed for the purposes of running cell phone equipment. As a result, there were no openly available, off-the-shelf software packages or solutions that would reliably interact wit
16、h their hardware. Since the manufacturers also wanted to guard very closely their hardware trade secrets, some of which could be revealed by allowing access to the software level of the device, the common practice was, and in most cases still is, to use completely proprietary and closed software to run their devices. The downside to this is that anyone who wanted to develop applications for cell phones needed to have intimate knowledge of t
