【文章內(nèi)容簡介】 den class, so V8 willmodify corresponding inner cache to make the direct use of the hidden class more convenient. If thisassumption is correct, the access of attributes can be all done in only 1 instruction. Even if the predictionfails, inner cache is modified again by V8, which won’t take too much time and resource. When one hidden class is shared by a lot of objects, the access speed can be close to most dynamic language access speed. Inner cache and hidden class, mixed with dynamic code and class optimization, improve the efficiency of JavaScript at a large scale [4]. . Effective Trash Cleaning V8 does memory recycles automatically. To guarantee the speed of object distribution, as well cut the time of trash cleaning and clear fragment up, V8 will interrupt the running application when performing trash cleaning. Mostly, only a small part of object stack is involved in trash cleaning cycle, so the interruption caused little. All location of objects and pointers are logged by V8, so the system won’t take object for pointer and memory overflow is avoided [4]. Besides ‘the most fluent web browser’, Google collaborated with Adobe and Android Froyo fully supports Flash. That’s to say, not only flash media, but all flash web pages can display perfectly on Android. To the contrary, Apple turned down Adobe and take HTML5 as iPhone’s web protocol, making it unable to show some flash based animation. Android Froyo also leads the way in work sharing. Smart phone with Froyo can be connected toa PC as a 3G NIC, and can also conveniently convert 3G signal to WiFi. iOS 4 can do the first too, butfailed to convert 3G to WiFi. Video conference is both supported by Froyo and iOS 4, but the conditions are different. You can see aFroyo user via camera as long as you get a camera also. However, iOS 4 user can only do video talk toanother iOS 4 user, which is a big limitation. While Android is ascendant in work interaction, Apple is unique 河北大學(xué) 21012屆本科畢業(yè)生外文文獻(xiàn)翻譯 6 in its friendship and added feature of ‘software classification’ enables user to place sorted softwar es into differentdocuments, making it clearer to manage. What’s more, there’re hundreds of thousands applications inApp Store, meaning that iPhone can have up to hundreds of thousands functions. This is a ratherremarkable feature that Apple publicizes. And the most convincing point given by Apple, is that ‘Android looks exactly familiar with iPhone.’ Although it’s just a subjective sense, the born of iPhone really brought big revolution to the phone industry, and the name ‘Apple’ itself is a world famous b rand [7] [8]. 3. Open and Closed platforms . SDK The most important part of every developing platform is SDK, enable 3rd party developers to make software for the platform. Usually, libraries, debug tools and emulators are included in SDK. Different platforms distribute their SDKs differently. Some SDK is plete free and open, while others are strictly limited. Developers of open platforms can get and modify part or all of the source code. Google and Linux are leaders of open platforms。 they publicized the whole source code of Android and Linux. The good point is that, platform owners can save a great amount of time and energy developing and maintaining the platform, because 3rd party developers will do this for them. With less money spent on development and maintenance, a relatively low price can attract more and more phone users. Contrarily, closed platforms lock their source code in the safety and forbid 3rd party accesses. Apple and Microsoft are the representatives of them, they are both closed sourced, but some differences do exists. 3rd party iPhone applications are restricted within narrow limits, for that Apple will look through every application which is uploaded onto ‘App Store’, and a lot of applications are turned don’t check Windows applications at all, it all depends on the users themselves. You installed the mareware, you suffer the loss. . Application Market Market is the medium between developers and users, hence it’s very 河北大學(xué) 21012屆本科畢業(yè)生外文文獻(xiàn)翻譯 7 important. Some predicted that there will be more and more application markets while some don’t think so. In current markets, both do exist. Some specify only one market