【正文】 如果組件沒有包含任何過濾器 ，它只能被顯式地指明作為目標(biāo)組件的 intent 激活。這個(gè)過程是通過比較 Intent 對象和所有潛在目標(biāo)的 intent 過濾器完成的。 丼例說明，一個(gè) activity可能聲明如下： activity元素的 name屬性指定了實(shí)現(xiàn)此 activity的 Activity子類。 service 可以通過調(diào)用自身的 stopSelf()方法，或調(diào)用 ()來停止。而broadcast receiver 僅在響應(yīng)一條廣播信息的時(shí)候處于活動狀態(tài)。 與此類似，一個(gè) intent 可以被傳遞給 ()以建立一個(gè)處于調(diào)用組件和目標(biāo) service 乀間的活動連接。相應(yīng)的 activity可以通過調(diào)用自身的 getIntent() 方法來查看最刜激活它的 intent。 激活組件： intent 當(dāng)接收到 ContentResolver 發(fā)出的請求后， content provider 被激活。通知一般是在狀態(tài)欄上放一個(gè)持麗的圖標(biāo)，用戶可以打開它并獲取消息。 3 Broadcast receiver 長春理工大學(xué)光電信息學(xué)院畢業(yè)設(shè)計(jì) 11 broadcast 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。為達(dá)到這個(gè)目的，媒體播放器 activity可以啟動一個(gè) 運(yùn)行于后臺的 service。content view 是位于層次結(jié)構(gòu)根位置的 View 對象。 窗口顯示的可視內(nèi)容是由一系列層次化 view構(gòu)成的，這些 view均繼承自 View 基類。每一個(gè)都實(shí)現(xiàn)為以 Activity類為基類的子類。你的應(yīng)用程序并沒有吸納或鏈接其它應(yīng)用程序的代碼。此文件是分發(fā)并安裝應(yīng)用程序到移動設(shè)備的載體；是用戶下載到他們的設(shè)備的文件。s ponents, such as naming any libraries the application needs to be linked against (besides the default Android library) and identifying any permissions the application expects to be granted. But the principal task of the manifest is to inform Android about the application39。s onActivityResult() method. 2. A service is started (or new instructions are given to an ongoing service) by passing an Intent object to (). Android calls the service39。s 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。t have a single entry point for everything in the application (no main() function, for example). Rather, they have essential ponents that the system can instantiate and run as needed. There are four 長春理工大學(xué)光電信息學(xué)院畢業(yè)設(shè)計(jì) 2 types of ponents: 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 acplished by having the current activity start the next one. Each activity is given a default window to draw in. Typically, the window fills the screen, but it might be smaller than the screen and float on top of other windows. An activity can also make use of additional windows — for example, a popup dialog that calls for a user response in the midst of the activity, or a window that presents users with vital information when they select a particular item onscreen. The visual content of the window is provided by a hierarchy of views — objects derived from the base View class. Each view controls a particular rectangular space within the window. Parent views contain and organize the layout of their children. Leaf views (those at the bottom of the hierarchy) draw in the rectangles they control and respond to user actions directed at that space. Thus, views are where the activity39。 it39。s possible to arrange for two applications to share the same user ID, in which case they will be able to see each other39。s not already running). While connected, you can municate with the service through an interface that the service exposes. For the music service, this interface might allow users to pause, rewind, stop, and restart the playback. Like activities and the other ponents, services run in the main thread of the application process. So that they won39。s onNewIntent() method to pass it any subsequent intents. One activity often starts the next one. If it expects a result back from the activity it39。re in a longrunning conversat