安卓系統(tǒng)的安全性外文翻譯

1、<p>　　本科畢業(yè)設(shè)計（論文）翻譯</p><p><b>　　班 級 </b></p><p>　　姓 名 </p><p>　　學(xué) 號 </p><p>　　指導(dǎo)教師 </p><p>&l

2、t;b>　　填表日期 </b></p><p>　　Understand android security </p><p>　　Security& Privacy, IEEE.2009,7</p><p>　　the next generation of open operating systems won’t be on deskto

3、ps or mainframes but on the small mobile devices we carry every day. The openness of these new environments will lead to new applications and markets and will enable greater integration with existing online services. <

4、;/p><p>　　However, as the importance of the data and services our cell phones support increases, so too do the opportunities for vulnerability. It’s essential that this next generation of platforms provide a co

5、mprehensive and usable security。 </p><p>　　infrastructure.Developed by the Open Handset Alliance (visibly led by Google), Android is a widely anticipated open source operating system for mobile devices that

6、provides a base operating system, an application middleware layer, a Java software development kit (SDK), and a collection of system applications. Although the Android SDK has been available since late 2007, the frst pub

7、licly available Android-ready “G1” phone debuted in late October 2008. Since then, Android’s growth has been phenome</p><p>　　A large community of developers has organized around Android, and many new produc

8、ts and applications are now available for it. One of Android’s chief selling points is that it lets developers seamlessly ，extend online services to phones. The most visible example of this feature is—unsurprisingly—the

9、tight integration of Google’s Gmail, Calendar, and Contacts Web applications with system utilities. Android users simply supply a username and password, and their phones automatically synchronize wit</p><p>

10、　　Traditional desktop and server operating systems have struggled to securely integrate such personal and business applications and services on a single platform; although doing so on a mobile platform such as Android re

11、mains nontrivial, many researchers hope it provides a clean slate devoid of the complications that legacy software can cause. Android doesn’t ofcially support applications eloped for other platforms: applications execute

12、 on top of a Java middleware layer running on an embedded Linu</p><p>　　Android Applications </p><p>　　The Android application framework forces a structure on developers. It doesn’t have a main(

13、) function or single entry point for execution—instead, developers must design applications in terms of components. </p><p>　　Example Application.</p><p>　　We developed a pair of applications to

14、 help describe how Android applications operate. Interested readers can download the source code from our web sitepttp://siis.cse.psu.edu/android_sec_tutorial.html).</p><p>　　Let’s consider a location-sensit

15、ive social networking 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 sh

16、ows, the FriendTracker application consists of components specifc to tracking friend locations (for example, via a Web service), storing geographic coordinates, and sharing those coordinates with other applications. The

17、user then uses the FriendVie</p><p>　　Both applications contain multiple components for performing their respective tasks; the components themselves are classifed by their component types. An Android develop

18、er chooses from predefned component types depending on the component’s purpose (such as interfacing with a user or storing data).</p><p>　　Component Types</p><p>　　Android defnes four component

19、types:</p><p>　　Activity? </p><p>　　components defne an application’s user interface. Typically, an application developer defnes one activity per “screen.” Activities start each other, possibly

20、passing and returning values. Only one activity on the system has keyboard and ocessing focus at a time; all others are suspended.</p><p><b>　　Service </b></p><p>　　components perfor

21、m 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 commonly starts a service specifcally designed f

22、or that action. The developer can also use services as application-specifc daemons, possibly starting on boot. Services often define an interface for Remote Procedure Call (RPC) that other system components can use to se

23、nd commands and retrieve data, as well as r</p><p>　　Content provider</p><p>　　? components store and share data using a relational database interface. Each content provider has an associated “

24、authority” describing the content it contains. Other components 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 typicall

25、y store values in database records, data retrieval is implementation-specifc—for example, fles are also shared through content provider interfaces.</p><p>　　Broadcast receiver? </p><p>　　compon

26、ents act as mailboxes for messages from other applications. Commonly, application code broadcasts messages to an implicit destination. Broadcast receivers thus sub-scribe to such destinations to receive the messages sent

27、 to it. Application code can also address a broadcast receiver explicitly by including the namespace assigned to its containing application. </p><p>　　Figure 1 shows the FriendTrack-er and FriendViewer appli

28、cations containing the diferent component types. The developer specifes components using a manifest fle (also used to defne policy as described later). There are no restrictions on the number of components an application

29、 defnes for each type, but as a convention, one component has the same name as the application. Frequently, this is an activity, as in the FriendViewer application. This activity usually indicates the primary activity th

30、at t</p><p>　　In this case, we reserved the name “FriendTracker” for the service component performing the core application logic.The FriendTracker application contains each of the four component types. The F

31、riendTracker service polls an external service to discover friends’ locations. In our example code, we generate locaFriendTracker application BootReceiver Broadcast receiver ActivityFriendTracker FriendProvider Content p

32、rovider Service FriendTracker control FriendViewer application FriendReceiver Broadcast</p><p>　　The Android API defines methods that accept intents, and uses that information to start activities (startActiv

33、ity(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 pr

34、ocess of intercomponent communication is known as an action. Simply put, an intent object defines the “intent” to perform an “action.”O(jiān)ne of Android’s most powerful featu</p><p>　　In the latter case, the sys

35、tem determines the best component for an action by considering the set of installed applications and user choices. The implicit name is called an action string because it specifies the type of requested action—for exampl

36、e, if the “VIEW” action string is specified in an intent with data fields pointing to an image fle, the system will direct the intent to the preferred image viewer. Developers also use action strings to broadcast a messa

37、ge to a group of broadcast receiv</p><p>　　Each component type supports interaction specifc to its type for example, when FriendViewer starts FriendMap, the FriendMap activity appears on the screen. Service

38、components 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 bet

39、ween components, allowing the initiator to execute RPCs defined by the service. In our example, FriendTracker binds </p><p>　　Android beginning</p><p>　　1.Using XML-Based Layouts</p><

40、p>　　While it is technically possible to create and attach widgets to our activity purely through Java code, the way we did in Chapter 4, the more common approach is to use an XML-based layout file. Dynamic instantiati

41、on of widgets is reserved for more complicated scenarios, where the widgets are not known at compile-time (e g., populating a column of radio buttons based on data retrieved off the Internet).With that in mind, it’s time

42、 to break out the XML and learn how to lay out Android activities t</p><p>　　1.1 What Is an XML-Based Layout?</p><p>　　As the name suggests, an XML-based layout is a specification of widgets’ re

43、lationships to each other—and to their containers (more on this in Chapter7—encoded in XML format. Specifically, Android considers XML-based layouts to be resources, and as such layout files are stored in the res/layout

44、directory inside your Android project. </p><p>　　Each XML file contains a tree of elements specifying a layout of widgets and their containers that make up one view hierarchy. The attributes of the XML eleme

45、nts are properties, describing how a widget should look or how a container should behave. For example, if a Button element has an attribute value of android: text Style = "bold",that means that the text appeari

46、ng on the face of the button should be rendered in a boldface font style. </p><p>　　Android’s SDK ships with a tool (aapt) which uses the layouts. This tool should be automatically invoked by your Android to

47、ol chain (e.g., Eclipse, Ant’s build.xml).Of particular importance to you as a developer is that aapt generates the R.java source file within your project, allowing you to access layouts and widgets within those layouts

48、directly from your Java code.</p><p>　　1.2Why Use XML-Based Layouts?</p><p>　　Most everything you do using XML layout files can be achieved through Java code. For example, you could use setTypef

49、ace() to have a button render its text in bold, instead of using a property in an XML layout. Since XML layouts are yet another file for you to keep track of, we need good reasons for using such files. Perhaps the bigges

50、t reason is to assist in the creation of tools for view definition, such as a GUI builder in an IDE like Eclipse or a dedicated Android GUI designer like DroidDraw1</p><p>　　Moreover, keeping generated XML d

51、efinitions separated from hand-written Java code makes it less likely that somebody’s custom-crafted source will get clobbered by accident when the generated bits get re-generated. XML forms a nice middle ground between

52、something that is easy for tool-writers to use and easy for programmers to work with by hand as needed.</p><p>　　Also, XML as a GUI definition format is becoming more commonplace. Microsoft’s XAML2, Adobe’s

53、Flex3, and Mozilla’s XUL4 all take a similar approach to that of Android: put layout details in an XML file and put programming smarts in source files (e.g., JavaScript for XUL). Many less-well-known GUI frameworks, such

54、 as ZK5, also use XML for view definition. While “following the herd” is not necessarily the best policy, it does have the advantage of helping to ease the transition into Android from a</p><p>　　<?xml ve

55、rsion="1.0" encoding="utf-8"?></p><p>　　<Button xmlns:android="http://schemas.android.com/apk/res/android"</p><p>　　android:id="@+id/button"</p&g