【正文】 le, 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 6 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. 。 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。 1 Understand android security the next generation of open operating systems won’t be on desktops 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. 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 prehensive and usable security by the Open Handset Alliance (visibly led by Google), Android is a widely anticipated open source operating system for mobile devices that 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 2021, the frst publicly available Androidready “G1” phone debuted in late October 2021. Since then, Android’s growth has been phenomenal: TMobile’s G1 manufacturer HTC estimates shipment volumes of more than 1 million phones by the end of 2021, and industry insiders expect public adoption to increase steeply in 2021. Many other cell phone providers have either promised or plan to support it in the near future. A large munity of de