【導讀】下一代操作系統(tǒng)本質在于是否提供一個完整綜合的安全平臺。盡管androidSDK自2020年就發(fā)布了，但是第一部android手。機卻在2020年10月才誕生。自從這時起谷歌開起了自己的時代，T-Mobile的。G1的制造商臺灣HTC估算G1的發(fā)貨量在2020年底已經(jīng)超過100萬部。內人士預期該G1手機的銷量將會在2020年繼續(xù)保持。不久的將來其他許多手。機供應商要計劃支持這個系統(tǒng)。一個Android的主要賣點是它使開發(fā)人員無縫把在線。這方面最明顯的例子是谷歌的緊密集成Gmail，日歷和聯(lián)系人。用戶只需提供一個android用戶名和密碼，其手機自。動同步與谷歌的服務。其他廠商正在迅速適應自己的現(xiàn)有的即時通訊，社交網(wǎng)絡。Android和許多企業(yè)尋找新途徑來整合他們的自己已有的業(yè)務到。傳統(tǒng)的臺式機和服務器的操作系統(tǒng)一直在努力進行安全功能的集成。發(fā)人員開發(fā)android應用人士透露，設計安全應用程序并不總是直線前進的。訓，希望對未來的安全有用。Android應用程序框架對開發(fā)者來說是一個強制架構。

　　

【正文】 friends’ locations. The FriendViewer activity lists all friends and their geographic coordinates, and the FriendMap activity displays them on a map. The FriendReceiver broadcast receiver waits for messages that indicate the physical phone is near a particular friend and displays a message to the user upon such an event. Although we could have placed these ponents within the FriendTracker application, we created a separate application to demonstrate crossapplication munication. dditionally, by separating the tracking and user interface logic, we can create alternative user interfaces with different displays and features—that is, many applications can reuse the logic performed in Interaction The primary mechanism for ponent interaction is an intent, which is simply a message object containing a destination ponent address and data. The Android API defnes methods that accept intents, and uses that information to start activities (startActivity(Intent)), start services (startService (Intent)), and broadcast messages (sendBroadcast(Intent)). The invocation of these methods tells the Android framework to begin executing code in the target application. This process of interponent munication is known as an action. Simply put, an intent object defnes the “intent” to perform an “action.”O(jiān)ne of Android’s most powerful features is the fexibility allowed by its intentaddressing mechanism. Although developers can uniquely address a target ponent using its application’s namespace, they can also specify an implicit name. In the latter case, the system determines the best ponent for an action by considering the set of installed applications and user choices. The implicit name is called an action string because it specifes the type of requested action—for example, if the “VIEW” action string is specifed in an intent with data felds pointing to an image fle, the system will direct the intent to the preferred image viewer. Developers also use action strings to broadcast a message to a group of broadcast receivers. On the receiving end, developers use an intent flter to subscribe to specifc action strings. Android includes additional destination resolution rules, but action strings with optional data types are the most 2 shows the interaction between ponents in the FriendTracker and FriendViewer applications and with ponents in applications defned as part of the base Android distribution. In each case, one ponent initiates munication with another. For simplicity, we call this interponent munication (ICC). In many ways, ICC is analogous to interprocess munication (IPC) in Unixbased systems. To the developer, ICC functions identically regardless of whether the target is in the same or diferent application, with the exception of the security rules defned later in this available ICC actions depend on the target ponent. Each ponent type supports interaction specifc to its type for example, when FriendViewer starts FriendMap, the FriendMap activity appears on the screen. Service ponents support start, stop, and bind actions, so the FriendTrackerControl activity, for instance, can start and stop the FriendTracker service that runs in the background. The bind action establishes a connection between ponents, allowing the initiator to execute RPCs defned by the service. In our example, FriendTracker binds to the location manager in the system server.