有關(guān)android技術(shù)英文文獻(xiàn)翻譯

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; its the file users download to their devices. All the code in a single .apk file is considered to be one application. Android應(yīng)用基礎(chǔ)：Android應(yīng)用程序是通過(guò)java語(yǔ)言開(kāi)發(fā)的，通過(guò)綁定一些應(yīng)用所需要的東西，例如：編譯的Java代碼，加上數(shù)據(jù)和一些資源文件，使用一個(gè)apt的工具將所有的東西封裝成一個(gè)android包，這個(gè)文件的文件后綴是.apk。這個(gè)文件是分發(fā)并安裝應(yīng)用程序到移動(dòng)設(shè)備的載體，是用戶獲得該應(yīng)用程序所需要的下載的文件。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 doesnt 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 is needed, and instantiate the Java objects for that part. Therefore, unlike applications on most other systems, Android applications dont have a single entry point for everything in the application (no main() function, for example). Rather, they have essential components that the system can instantiate and run as needed. There are four types of components: Activities An activity presents a visual user interface for one focused endeavor the user can undertake. For example, an activity might present a list of menu items users can choose from or 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 message to the chosen contact, and other activities to review old messages or change settings. Though they work together to form a cohesive user interface, each activity is independent of the others. Each 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有四大應(yīng)用程序組件Android的一個(gè)很重要的中心特征就是一個(gè)應(yīng)用程序能充分利用其他的應(yīng)用程序的一些組件（前提是被允許的） 例如：如果的當(dāng)前開(kāi)發(fā)的應(yīng)用需要一個(gè)滾動(dòng)的列表去展示相片并且當(dāng)時(shí)其他的程序已經(jīng)開(kāi)發(fā)了一個(gè)合適的滾動(dòng)列表并且對(duì)其他人可用，你可以調(diào)用這個(gè)滾動(dòng)的列表來(lái)完成你的工作而不是開(kāi)發(fā)你自己的。你的應(yīng)用不需要包含那個(gè)應(yīng)用的代碼或來(lái)鏈接它。相反，它只是簡(jiǎn)單的在你需要它是啟動(dòng)這部分的應(yīng)用為了實(shí)現(xiàn)這部分的功能，當(dāng)前系統(tǒng)必須能啟動(dòng)其他應(yīng)用程序進(jìn)程的功能當(dāng)那些部分它需要時(shí)，并且為這部分的java對(duì)象初始化這個(gè)java對(duì)象。因此，不想在其他系統(tǒng)中的應(yīng)用程序，android應(yīng)用程序不需要一個(gè)單一的入口點(diǎn)（例如:沒(méi)有main（）而是，提供了實(shí)例化和運(yùn)行所需的必備組件。Android有四大應(yīng)用程序組件1：activity一個(gè)Activity基類是為展示可視化用戶接口。例如：一個(gè)Activity可以顯示一個(gè)供用戶選擇的菜單列表，或者可以展示一些圖片以及對(duì)應(yīng)的說(shuō)明。一個(gè)短信的應(yīng)用有一個(gè)活動(dòng)顯示發(fā)送消息的一系列的聯(lián)系人，第二個(gè)活動(dòng)去編寫(xiě)信息文本去選擇聯(lián)系人，第三個(gè)活動(dòng)去查看以前的信息或修改一些設(shè)置。雖然它們組成了一個(gè)內(nèi)聚的用戶界面，每一個(gè)活動(dòng)都和其他的的相互獨(dú)立，每一個(gè)都繼承Activity，是Activity的子類。一個(gè)應(yīng)用程序可以只有一個(gè)Activity，但是也可以有多個(gè)，比如剛剛提到的文本應(yīng)用。每個(gè)程序的作用，有多少個(gè)程序，取決于該應(yīng)用的設(shè)計(jì)。ServicesA service doesnt 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：services服務(wù)是android中一個(gè)在后臺(tái)運(yùn)行的應(yīng)用程序，沒(méi)有可視化的用戶界面。例如：你可以在使用一個(gè)用戶程序的同時(shí)播放背景音樂(lè)。并且此時(shí)，播放音樂(lè)的代碼就不需要和用戶交互，因此可以作為一個(gè)服務(wù)來(lái)運(yùn)行，并且使用用戶服務(wù)的接口來(lái)實(shí)現(xiàn)音樂(lè)的播放，暫停，等功能。對(duì)于不用向用戶展示用戶界面的情況下，使用服務(wù)是一個(gè)理想的選擇。如同其他的組件一樣，services運(yùn)行于應(yīng)用程序進(jìn)程的主線程內(nèi)。所以它不會(huì)對(duì)其他組件或用戶界面有任何的妨礙，他們一般會(huì)派生一個(gè)新線程來(lái)執(zhí)行一些時(shí)間消耗型的任務(wù)。Broadcast receivers A broadcast receiver is a component that does nothing but receive and react to broadcast announcements. Many broadcasts originate in system code for example, announcements that the time zone has changed, that the battery is low, that a picture has been taken, or that the user changed a language preference. Applications can also initiate broadcasts for example, to let other applications know that some data has been downloaded to the device and is available for them to use. An application can have any number of broadcast receivers to respond to any announcements it considers important. All receivers extend the BroadcastReceiver base class. Broadcast receivers do not display a user interface. However, they may start an activity in response to the information they receive, or they may use the NotificationManager to alert the user. Notifications can get the users attention in various ways flashing the backlight, vibrating the device, playing a sound, and so on. They typically place a persistent icon in the status bar, which users can open to get the3：Broadcast receiverbroadcast receiver是一個(gè)與注于接收廣播通知信息并做出相應(yīng)處理的組件。許多廣播是由系統(tǒng)代碼產(chǎn)生的例如通知時(shí)區(qū)改變、電池電量低、拍攝了一張照片或者用戶改變了語(yǔ)言選項(xiàng)。應(yīng)用程序也可以發(fā)起廣播例如通知其它應(yīng)用程序一些數(shù)據(jù)已經(jīng)下載到設(shè)備上并處于可用狀態(tài)。 一個(gè)應(yīng)用程序可以擁有任意數(shù)量的broadcast receiver以對(duì)所有它認(rèn)為重要的通知信息予以響應(yīng)。所有的receiver均繼承自BroadcastReceiver基類。 broadcast receiver沒(méi)有用戶界面。然而它們可以啟動(dòng)一個(gè)activity來(lái)響應(yīng)它們收到的信息或者也可以使用NotificationManager來(lái)通知用戶。通知可以用多種方式來(lái)吸引用戶的注意力閃動(dòng)背光燈、震動(dòng)設(shè)備、播放聲音等等。通知一般是在狀態(tài)欄上放一個(gè)持續(xù)的圖標(biāo)用戶可以打開(kāi)它并獲取消息。Content providers A content provider makes a specific set of the applications data available to other applications. The data can be stored in the file system, in an SQLite database, or in any other manner that makes sense. The content provider extends the ContentProvider base class to implement a standard set of methods that enable other applications to retrieve and store data of the type it controls. However, applications do not call these methods directly. Rather they use a ContentResolver object and call its methods instead. A ContentResolver can talk to any content provider; it cooperates with the provider to manage any interprocess communication thats involved. See the separate Content Providers document for more information on using content providers. Whenever theres a request that should be handled by a particular component, Android makes sure that the application process of the component is running, starting it if necessary, and that an appropriate instance of the component is available, creating the instance if necessary. 4：內(nèi)容提供者content providercontent provider將一些特定的應(yīng)用程序數(shù)據(jù)供給其它應(yīng)用程序使用。數(shù)據(jù)可以存儲(chǔ)于文件系統(tǒng)、SQLite數(shù)據(jù)庫(kù)或其它有意義的方式。content provider繼承于ContentProvider 基類實(shí)現(xiàn)了一套使得其他應(yīng)用程序能夠檢索和存儲(chǔ)它所管理類型數(shù)據(jù)的標(biāo)準(zhǔn)方法。然而應(yīng)用程序并不直接調(diào)用返些方法而是使用一個(gè) ContentResolver 對(duì)象調(diào)用它的方法作為替代。ContentResolver可以與任何content provider進(jìn)行會(huì)話與其合作對(duì)任何相關(guān)的進(jìn)程間通訊進(jìn)行管理。 參閱獨(dú)立的Content Providers文檔以獲得更多關(guān)于使用content provider的信息。 每當(dāng)出現(xiàn)一個(gè)需要被特定組件處理的請(qǐng)求時(shí)Android會(huì)確保那個(gè)組件的應(yīng)用程序進(jìn)程處于運(yùn)行狀態(tài)必要時(shí)會(huì)啟動(dòng)它并確保那個(gè)組件的一個(gè)合適的實(shí)例可必要時(shí)會(huì)創(chuàng)建那個(gè)實(shí)例。Activating Components激活組件Three of the four component typesactivities, services, and broadcast receiversare activated by an asynchronous message called anintent. Intents bind individual components to each other at runtime (you can think of them as the messengers that request an action from other components), whether the component belongs to your application or another.四種類型組件中的三種：活動(dòng) 服務(wù)和廣播接受者都通過(guò)一個(gè)叫做intent的異步消息激活。這些intents在運(yùn)行時(shí)（runtime）將這些屬于你的程序或不同程序的單獨(dú)的組件綁定在一起（bind），你可以把這些intents看作是需要其他組件的action的messengers。An intent is created with anIntentobject, which defines a message to activate either a specific component or a specifictypeof componentan intent can be either explicit or implicit, respectively.一個(gè)Intent通過(guò)一個(gè)Intent對(duì)象建立，該Intent對(duì)象定義了一個(gè)消息去激活一個(gè)特殊的組件或一種特殊的組件-一個(gè)Intent既可以明確的說(shuō)明也可以不明確，要分情況來(lái)看For activities and services, an intent defines the action to perform (for example, to view or send something) and may specify the URI of the data to act on (among other things that the component being started might need to know). For example, an intent might convey a request for an activity to show an image or to open a web page. In some cases, you can start an activity to receive a result, in which case, the activity also returns the result in anIntent(for example, you can issue an intent to let the user pick a personal contact and have it returned to youthe return intent includes a URI pointing to the chosen contact).對(duì)于活動(dòng)和服務(wù)，一個(gè)Intent定義了一個(gè)動(dòng)作去執(zhí)行（比如：要View或者send什么）和要操作數(shù)據(jù)的uri，一個(gè)Intent可能傳遞了為一個(gè)Activity傳遞了一個(gè)請(qǐng)求去展示一張圖片或者打開(kāi)一個(gè)網(wǎng)頁(yè)在這些例子中，你可以開(kāi)始一個(gè)活動(dòng)去接收結(jié)果，在這個(gè)例子中，這個(gè)Activity也可以返回這個(gè)通過(guò)一個(gè)Intent返回一個(gè)結(jié)果（例如，你可以發(fā)動(dòng)一個(gè)Intent去讓用戶選擇一個(gè)個(gè)人的contact并且返回給你，這個(gè)返回的意圖包括一個(gè)指向這個(gè)聯(lián)系人的URI）For broadcast receivers, the intent simply defines the announcement being broadcast (for example, a broadcast to indicate the device battery is low includes only a known action string that indicates battery is low).對(duì)于廣播接收者來(lái)說(shuō)，intent只是簡(jiǎn)單的定義了要廣播的內(nèi)容（比如，一個(gè)用以表明電池電量很低的廣播僅包含了一個(gè)表明電池電量很低的字符串）。The other component type, content provider, is not activated by intents. Rather, it is activated when targeted by a request from aContentResolver. The content resolver handles all direct transactions with the content provider so that the component thats performing transactions with the provider doesnt need to and instead calls methods on theContentResolverobject. This leaves a layer of abstraction between the content provider and the component requesting information (for security).另外一個(gè)組件的類型，內(nèi)容提供者，不是通過(guò)意圖激活。而是由接收到contentResolver請(qǐng)求是激活的這個(gè)內(nèi)處理者處理所有的直接的事務(wù)通過(guò)內(nèi)容提供者。因此，There are separate methods for activating each type of component:這里有不同的方法來(lái)激活不同類型的組件 You can start an activity (or give it something new to do) by passing anIntenttostartActivity()orstartActivityForResult()(when you want the activity to return a result). 你可啟動(dòng)一個(gè)一個(gè)活動(dòng)（或者給他一些新的要做的內(nèi)容）通過(guò)傳遞一個(gè)Intent來(lái)startActivity () 或者startActivityForResult（）（當(dāng)你需要這個(gè)Activity返回一個(gè)結(jié)果時(shí)） You can start a service (or give new instructions to an ongoing service) by passing anIntenttostartService(). Or you can bind to the service by passing anIntenttobindService().你可以啟動(dòng)一個(gè)Service（或者給一個(gè)內(nèi)在的服務(wù)一些新的指令）通過(guò)傳遞一個(gè)Intent來(lái)startServices（）,或者你可以通過(guò)把一個(gè)Intent傳遞給bindService()來(lái)綁定一個(gè)service。 You can initiate a broadcast by passing anIntentto methods likesendBroadcast(),sendOrderedBroadcast(), orsendStickyBroadcast().你可以通過(guò)傳遞一個(gè)Intent給諸如sendBroadcast()、sendOrderedBroadcast()或者sendStickyBroadcast()等方法來(lái)初始化一個(gè)廣播。 You can perform a query to a content provider by callingquery()on aContentResolver.你可以通過(guò)調(diào)用ContentResolver的query()方法來(lái)執(zhí)行一次contentprovider的查詢操作。For more information about using intents, see theIntents and Intent Filtersdocument. More information about activating specific components is also provided in the following documents:Activities,Services,BroadcastReceiverandContent Providers. 更多關(guān)于使用Intent的信息，查看Intent和IntentFilters文檔。更多關(guān)于如何激活特定的組件同樣在下面的文檔中提供：Activities,Services,BroadcastReceiverandContent Providers. Declaring components聲明組件The primary task of the manifest is to inform the system about the applications components. For example, a manifest file can declare an activity as follows:Manifest的首要的任務(wù)就是聲明系統(tǒng)中有關(guān)這個(gè)應(yīng)用的組件。例如，一個(gè)manifest文件可以通過(guò)聲明一個(gè)Activity如下： . In theelement, theandroid:iconattribute points to resources for an icon that identifies the application.在這個(gè)元素中android:icon屬性指向一個(gè)資源（用來(lái)表示當(dāng)前這個(gè)應(yīng)用程序的圖標(biāo)）In theelement, theandroid:nameattribute specifies the fully qualified class name of theActivitysubclass and theandroid:labelattributes specifies a string to use as the user-visible label for the activity.在 這個(gè)元素中，android :name屬性用于確定繼承Activity的的子類的全路徑名android:label屬性用于表示這個(gè)用戶可見(jiàn)的標(biāo)簽 You must declare all application components this way:你必須通過(guò)一下的方法來(lái)聲明這些應(yīng)用組件l elements for activitiesl elements for servicesl elements for broadcast receiversl elements for content providersactivities：標(biāo)簽services:標(biāo)簽broadcastreceiver：標(biāo)簽contentproviders：標(biāo)簽Activities, services, and content providers that you include in your source but do not declare in the manifest are not visible to the system and, consequently, can never run. However, broadcast receivers can be either declared in the manifest or created dynamically in code (asBroadcastReceiverobjects) and registered with the system by callingregisterReceiver().如果你的程序中用到了活動(dòng)，服務(wù)，內(nèi)容提供者但是沒(méi)有在manifest中聲明，結(jié)果是這些組件不會(huì)被系統(tǒng)所知道從而不會(huì)運(yùn)行。但是，broadcast Receivers 既可以在manifest中聲明也可以動(dòng)態(tài)的通過(guò)代碼來(lái)創(chuàng)建（作為broadcast Receivers對(duì)象）并且使用registerReceiver()在系統(tǒng)中注冊(cè) Declaring component capabilities聲明組件的能力As discussed above, inActivating Components, you can use anIntentto start activities, services, and broadcast receivers. You can do so by explicitly naming the target component (using the component class name) in the intent. However, the real power of intents lies in the concept of intent actions. With intent actions, you simply describe the type of action you want to perform (and optionally, the data upon which youd like to perform the action) and allow the system to find a component on the device that can perform the action and start it. If there are multiple components that can perform the action described by the intent, then the user selects which one to use.就像上面說(shuō)的那樣，在激活組件的時(shí)候，你可以使用Intent來(lái)開(kāi)始活動(dòng)，服務(wù)，內(nèi)容提供者。你可以明確的在Intent中聲明目標(biāo)組件的名稱（使用組件的類名）。但是，Intent的真正的能力取決于Intent的action的概念，你可以簡(jiǎn)單的描述你要操作的動(dòng)作的類型（或者是有選擇的描述你要的在動(dòng)作中使用的數(shù)據(jù)），并且可以允許系統(tǒng)找到一個(gè)在設(shè)備上組件執(zhí)行和啟動(dòng)它。如果有多個(gè)在Intent中描述能執(zhí)行動(dòng)作的組件，則可以讓用戶去選擇自己想用的The way the system identifies the components that can respond to an intent is by comparing the intent received to theintent filtersprovided in the manifest file of other applications on the device.系統(tǒng)識(shí)別能對(duì)Intent做出響應(yīng)的方式是通過(guò)比較接收到的Intent和設(shè)備中應(yīng)用程序的manifest文件中的Intent filtersWhen you declare a component in your applications manifest, you can optionally include intent filters that declare the capabilities of the component so it can respond to intents from other applications. You can declare an intent filter for your component by adding anelement as a child of the components declaration element.當(dāng)你在應(yīng)用的manifest中聲明一個(gè)組件時(shí)，你可以有選擇的包含Intent filters，這些Intent filters表明了這些組件對(duì)其他應(yīng)用程序的Intent做出反應(yīng)的能力。你可以通過(guò)添加一個(gè)作為 來(lái)為你的組件聲明一個(gè)Intent filtersFor example, an email application with an activity for composing a new email might declare an intent filter in its manifest entry to respond to send intents (in order to send email). An activity in your application can then create an intent with the “send” action (ACTION_SEND), which the system matches to the email applications “send” activity and launches it when you invoke the intent withstartActivity().例如：一個(gè)有處理新郵件Activity的郵件應(yīng)用也許可以聲明一個(gè)Intent filter在它的manifest入口中來(lái)作為send Intent（為了send Email ),在你的應(yīng)用中可以創(chuàng)建一個(gè)帶有發(fā)送的Intent（action_send），當(dāng)你用startactivity()調(diào)用這個(gè)Intent，系統(tǒng)在郵件程序中匹配一個(gè)send的Activity并且運(yùn)行它For more about creating intent filters, see theIntents and Intent Filtersdocument.Declaring application requirements聲明運(yùn)行程序所需要的條件There are a variety of devices powered by Android and not all of them provide the same features and capabilities. In order to prevent your application from being installed on devices that lack features needed by your application, its important that you clearly define a profile for the types of devices your application supports by declaring device and software requirements in your manifest file. Most of these declarations are informational only and the system does not read them, but external services such as Google Play do read them in order to provide filtering for users when they search for applications from their device.有多種多樣的設(shè)備上運(yùn)行著android系統(tǒng)并且不是所有的設(shè)別都提供相同的特征和能力，為了防止你的程序安裝在缺乏相應(yīng)功能的設(shè)備上，在你的manifest未見(jiàn)中聲明硬件和軟件的要求（為了讓你的應(yīng)用被不同的設(shè)備支持）變得尤為的重要。大多數(shù)這些信息和聲明并不會(huì)被系統(tǒng)讀取。但是其他的服務(wù)比如AndroidMarket卻會(huì)閱讀這些聲明來(lái)幫助通過(guò)通過(guò)自己的設(shè)備搜索軟件的用戶過(guò)濾軟件。For example, if your application requires a camera and uses APIs introduced in Android 2.1 (API Level7), you should declare these as requirements in your manifest file. That way, devices that donothave a camera and have an Android versionlowerthan 2.1 cannot install your application from Google Play.比如：你的應(yīng)用需要照相和android 2.1的api，你應(yīng)該在你的manifest文件中聲明這些要求。通過(guò)這種方法，這些沒(méi)有相機(jī)功能或者是android版本低于2.1的不能沖Google play中安裝該應(yīng)用However, you can also declare that your application uses the camera, but does notrequireit. In that case, your application must perform a check at runtime to determine if the device has a camera and disable any features that use the camera if one is not available.然而，你也可以在你的應(yīng)用中使用相機(jī)，但是并不是需要它。在這個(gè)情況下，你的應(yīng)用在運(yùn)行時(shí)必須執(zhí)行一次檢查來(lái)確定這個(gè)設(shè)備是否有相機(jī)。如果你的設(shè)備沒(méi)有相機(jī)，那么系統(tǒng)會(huì)使使用照相機(jī)的相關(guān)程序不可用Here are some of the important device characteristics that you should consider as you design and develop your application:在你設(shè)計(jì)和開(kāi)發(fā)你的應(yīng)用程序的時(shí)候，這里是一些你應(yīng)該考慮的重要的設(shè)備特征Screen size and density屏幕尺寸和分辨率In order to categorize devices by their screen type, Android defines two characteristics for each device: screen size (the physical dimensions of the screen) and screen density (the physical density of the pixels on the screen, or dpidots per inch). To simplify all the different types of screen configurations, the Android system generalizes them into select groups that make them easier to target.為了對(duì)屏幕類型進(jìn)行分類。Android為每個(gè)設(shè)備定義了2個(gè)重要的特征：屏幕大小和屏幕分辨率。為了簡(jiǎn)化所有屏幕配置的不同類型，android系統(tǒng)把他們集中到一起去選擇來(lái)更好的去瞄準(zhǔn)The screen sizes are: small, normal, large, and extra large.The screen densities are: low density, medium