怎么部署Andriod的开发环境：
- JRE （Eclipse的运行环境）http://www.java.com/en/download/manual.jsp
- Eclipse（the "Eclipse Classic" version is recommended 开发调试工具，推荐下载经典版），安装好JRE后，直接解压Eclispse.zip文件，例如至：C:\Program Files，然后就可运行exlipse.exe了。 http://www.eclipse.org/downloads/
- Andriod SDK 下载好后，直接解压Andriod.zip文件，例如至：C:\Program Files。http://androidappdocs.appspot.com/sdk/index.html
- ADT (Andriod Development Tools)—a custom plugin for the Eclipse IDE to build Andriod applications。安装方法见此页面：http://androidappdocs.appspot.com/sdk/eclipse-adt.html 在Help->Install New Software界面中点击Add，添加ADT Plugin的在线安装地址：
https://dl-ssl.google.com/android/eclipse/或者http://dl-ssl.google.com/android/eclipse/，等列出资源表后，全部选上安装就OK了。重启Eclipse就能看到多出几个Andriod模拟器图标了。 - Modify Eclipes preferences to point to the Andriod SDK directory. 在Window->Prefences，选中Andriod，在右边的SDK Location中定位到之前的解压目录。
- 接下来在界面上点击手机模拟器图标，下载所需要的开发包和文档以及USB驱动。例如，可以选2.1和1.5两个版本。AVD(Andriod Virtual Device) The Android SDK starter package includes only a single component: the latest version of the SDK Tools. Included in that component is a tool called Android SDK and AVD Manager that you can use to download other components from the SDK repository site. The tool provides a graphical UI that lets you browse the repository, select new or updated components for download, and then install them in your SDK.
- 下载完成后转到虚拟设备里面，创建模拟设备，设置好名字和系统版本。这样就可以开始写Hello World，进行Andriod之旅了。
一些术语：
IME—-Input Method Editor 也就是常说的“输入法”
Screen size—-Actual physical size, measured as the screen’s diagonal
Resolution—-The total number of physical pixels on a screen. Note that, although resolution is often expressed as width x height, resolution does not imply a specific aspect ratio.
Density—-Based on the screen resolution, the spread of pixels across the physical width and height of the screen. A screen with lower density has fewer available pixels spread across the screen width and height, where a screen with higher density has more — sometimes significantly more — pixels spread across the same area. The density of a screen is important because, other things being equal, a UI element (such as a button) whose height and width are defined in terms of screen pixels will appear larger on the lower density screen and smaller on the higher density screen. 像素密度=像素总数/屏幕面积
Density independent pixel (dip)—-
A virtual pixel unit that applications can use in defining their UI, to express layout dimensions or position in a density-independent way.
The density-independent pixel is equivalent to one physical pixel on a 160 dpi screen, the baseline density assumed by the platform (as described later in this document). At run time, the platform transparently handles any scaling of the dip units needed, based on the actual density of the screen in use. The conversion of dip units to screen pixels is simple:
pixels = dips * (density / 160). For example, on 240 dpi screen, 1 dip would equal 1.5 physical pixels. Using dip units to define your application’s UI is highly recommended, as a way of ensuring proper display of your UI on different screens. Andriod密度：160DPI的密度系数是1。VGA(Video Graphics Array)—-是IBM在1987年随PS／2机一起推出的一种视频传输标准。在手机屏幕中意思只表示指手机的分辨率，与手机液晶屏幕的TFT材质和手机屏幕大小尺寸都没有关系。
VGA是640*480像素
QQVGA(Quarter Quarter VGA)—-160*120像素
QVGA(Quarter VGA)—-VGA的四分之一尺寸 320*240像素
WQVGA(Wide Quarter VGA)—-400*240像素
HVGA(Half-size VGA)—-VGA的一半 320*480像素
WVGA(Wide VGA)—-800*480像素
SVGA(Super VGA)—-800*600像素
XGA(Extended Graphics Array)—-1024*768像素
WXGA(Wide eXtended Graphics Array)—-1280*768像素
Quad-VGA—-1280*960像素
WXGA+(Wide XGA+)—-1440*900像素
SXGA(Super XGA)—-1280*1024像素
WXGA++(Wide XGA++)—-1600*900像素
SXGA+(Super XGA+)—-1400*1050像素—-我的本本就是这个像素！
UXGA(Ultra XGA)—-1600*1200像素
WUXGA(Wide Ultra XGA)—-1920*1200像素
QXGA(Quad XGA)—-2048*1536像素
QSXGA(Quad Super XGA)—-2560*2048像素
同样的分辨率，屏幕越小，显示越细腻。
