【導讀】越來越完善，他的系統(tǒng)平臺也日漸火熱起來。目前國內(nèi)最常見的移動系統(tǒng)平臺有。Symbian，iPhone，WindowsPhone以及當下正在逐步興起的Android。截止2020年第二季度Android系統(tǒng)的國內(nèi)。市場占有率已經(jīng)過10%，在西歐以及北美智能手機市場占有率也在20%左右。但是對于Android系統(tǒng)的應用和開發(fā)在國內(nèi)仍然屬。于起步和探索階段。急需要大量的相關(guān)技術(shù)和人員的投入。下面首先介紹一下Android系統(tǒng)。Android是基于Linux內(nèi)核的軟件平臺和操。它采用了軟件堆層（Softwarestack，又。名以軟件疊層）的架構(gòu)，主要分為三部分。低層以Linux核心工作為基礎(chǔ)，只提供。全球在使用的移動電話已經(jīng)超過10億部，而且這個數(shù)字每天都在不斷增。在國內(nèi)Android相關(guān)領(lǐng)域?qū)儆谳^早研究的一。的學習交上一份圓滿的答卷。目前國外各軟硬件廠商已經(jīng)推出過多款手機操作系統(tǒng)。目前國內(nèi)還沒有自主研發(fā)并商品化的手機操作系統(tǒng)。在2020年8月，由中國移動所主導開發(fā)OPhone平臺面世。目前手機應用中數(shù)量最大，使用人數(shù)最多的應用類型是手機游戲。實現(xiàn)，在android平臺上的QuickOffice就是這樣的軟件。

　　

【正文】 d several potentially confusing refnements as the system has article attempts to unmask the plexity of Android security and note some possible development pitfalls that occur when defning an application’s security. We conclude by attempting to draw some lessons and identify opportunities for future enhancements that should aid in clarity and Applications The Android application framework forces a structure on developers. It doesn’t have a main() function or single entry point for execution—instead, developers must design applications in terms of ponents. Example Application. We developed a pair of applications to help describe how Android applications operate. Interested readers can download the source code from our web Let’s consider a locationsensitive social working application for mobile phones in which users can discover their friends’locations. We split the functionality into two applications: one for tracking friends and one for viewing them. As Figure 1 shows, the FriendTracker application consists of ponents specifc to tracking friend locations (for example, via a Web service), storing geographic coordinates, and sharing those coordinates with other applications. The user then uses the FriendViewer application to retrieve the stored geographic coordinates and view friends on a applications contain multiple ponents for performing their respective tasks。 the ponents themselves are classifed by their ponent types. An Android developer chooses from predefned ponent types depending on the ponent’s purpose (such as interfacing with a user or storing data).Component TypesAndroid defnes four ponent types:Activity? ponents defne an application’s user interface. Typically, an application developer defnes one activity per “screen.” Activities start each other, possibly passing and returning values. Only one activity on the system has keyboard and ocessing focus at a time。 all others are ponents perform background processing. When an activity needs to perform some operation that must continue after the user interface disappears (such as download a fle or play music), it monly starts a service specifcally 29 designed for that action. The developer can also use services as applicationspecifc daemons, possibly starting on boot. Services often define an interface for Remote Procedure Call (RPC) that other system ponents can use to send mands and retrieve data, as well as register callbacks. Content provider ? ponents store and share data using a relational database interface. Each content provider has an associated “authority” describing the content it contains. Other ponents use the authority name as a handle to perform SQL queries (such as SELECT, INSERT, or DELETE) to read and write content. Although content providers typically store values in database records, data retrieval is implementationspecifc—for example, fles are also shared through content provider receiver? ponents act as mailboxes for messages from other applications. Commonly, application code broadcasts messages to an implicit destination. Broadcast receivers thus subscribe to such destinations to receive the messages sent to it. Application code can also address a broadcast receiver explicitly by including the namespace assigned to its containing application. Figure 1 shows the FriendTracker and FriendViewer applications containing the diferent ponent types. The developer specifes ponents using a manifest fle (also used to defne policy as described later). There are no restrictions on the number of ponents an application defnes for each type, but as a convention, one ponent has the same name as the application. Frequently, this is an activity, as in the FriendViewer application. This activity usually indicates the primary activity that the system application launcher uses to start the user interface。 however, the specifc activity chosen on launch is marked by meta information in the manifest. In the FriendTracker application, for example, the FriendTrackerControl activity is marked as the main user interface entry point. In this case, we reserved the name “FriendTracker” for the service ponent performing the core application FriendTracker application contains each of the four ponent types. The FriendTracker service polls an external service to discover friends’ locations. In our example code, we generate locaFriendTracker application BootReceiver Broadcast receiver ActivityFriendTracker FriendProvider 30 Content provider Service FriendTracker control FriendViewer application FriendReceiver Broadcast receiver Activity FriendTracker Activity FriendViewer Figure 1. Example Android application. The FriendTracker and FriendViewer applications consist of multiple ponents of different types, each of which provides a different set of functionalities. Activities provide a user interface, services execute background processing, content providers are data storage facilities, and broadcast receivers act as mailboxes for messages from other randomly, but extending the ponent to interface with a Web service is straightforward. The FriendProvider content provider maintains the most recent geographic coordinates for friends, the FriendTrackerControl activity defnes a user interface for starting and stopping the tracking functionality, and the BootReceiver broadcast receiver obtains a notifcation from the system once it boots (the application uses this to utomatically start the FriendTracker service).The FriendViewer application bis primarily concerned with showing information about 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 t