有关android技术英文文献翻译资料.pdf

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Application Fundamentals

Android applications are written in the Java programming language. The compiled Java code

—

along with any data and resource files required by the application

—

is bundled by the aapt tool

into an Android package, an archive file marked by an .apk suffix. This file is the vehicle for

distributing the application and installing it on mobile devices; it's the file users download to their

个 an droid 包，这个文件的文件后缀是 .apk。这个文件是分发并安装应用程序到移动设备 的载体，是

用户获得该应用程序所需要的下载的文件。

Application Components A central feature of Android is that one application can make use of

elements of other applications (provided those applications permit it). For example, if your

application needs to display a scrolling list of images and another application has developed a

suitable scroller and made it available to others, you can call upon that scroller to do the work,

rather than develop your own. Your application doesn't incorporate the code of the other

application or link to it. Rather, it simply starts up that piece of the other application when the need

arises. For this to work, the system must be able to start an application process when any part of it

might display photographs along with their captions. A text messaging application might have one

activity that shows a list of contacts to send messages to, a second activity to write the messageto

the chosen contact, and other activities to review old messagesor change settings. Though they

work together to form a cohesive user interface, each activity is independent of the others. Each

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one is implemented as a subclass of the Activity base class. An application might consist of just

one activity or, like the text messaging application just mentioned, it may contain several. What the

activities are, and how many there are depends, of course, on the application and its design.

Typically, one of the activities is marked as the first one that should be presented to the user when

the application is launched. Moving from one activity to another is accomplished by having the

current activity start the next one. Android

相反，它只是简单的在你需要它是启动这部分的应用 为了实现这部分的功能， 当前系统必须能启动其

他应用程序进程的功能当那些部分它需 要时，并且为这部分的

对象初始化这个

java

对象。因此，

不想在其他系统中的应 用程序，

an droid

应用程序不需要一个单一的入口点（例如

：

没有

main

（））

而是，提供 了实例化和运行所需的必备组件。

Android

基类是为展示可视化用户接口。 例如：一个

Activity

可以显示一个供用 户选择的菜

Services

A service doesn't have a visual user interface, but rather runs in the background for an indefinite

period of time. For example, a service might play background music as the user attends to other

matters, or it might fetch data over the network or calculate something and provide the result to

activities that need it. Each service extends the Service base class.

2

：

服务是

an droid

中一个在后台运行的应用程序，没有可视化的用户界面。

例如：你可以在使用一个用户程序的同时播放背景音乐。并且此时，播放音乐的代码就 不需要和用户交

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Broadcast receivers

A broadcast receiver is a comp onent that does nothing but receive and react to broadcast announ

ceme nts. Many broadcasts orig in ate in system code

time zone has changed, that the battery is low, that a picture has been taken, or that the user cha

nged a Ian guage prefere nee. Applicati ons can also in itiate broadcasts for example, to let other

applicati ons know that some data has bee n dow nl oaded to the device and is available for them

to use.

An applicati on can have any nu mber of broadcast receivers to resp ond to any announ ceme nts

it considers important. All receivers extend the BroadcastReceiver base class. Broadcast

broadcast receiver

是?个与注

收广播泄知唁 . ；：讥岀杠应处 - 貝

勺紺 . 牛

，.:

许多广播是由系统代码产生的一一 例如 迪知忙

收变?、匕池电竝攸 扪赛了「■帐 照片或者用

户改变了语言选项。应用程序也可以发起广播一一 例如 泄知

应用 程序一些数据已经下载到设

备上并处于可用状态。

一个应用程序可以拥有任意数量的

NotificationManager

式来吸引用户的注意力一一闪动背光灯、震动设备、播放声音等等。通知一般是在

Content providers

A content provider makes a specific set of the applicati on's data available to other applicati ons.

The data can be stored in the file system, in an SQLite database, or in any other manner that