中英文文獻(xiàn)java

1、東北石油大學(xué)本科畢業(yè)設(shè)計(jì)英文文獻(xiàn)及翻譯 學(xué)院計(jì)算機(jī)與信息技術(shù)學(xué)院班級(jí)學(xué)號(hào)姓名指 導(dǎo) 教 師王 輝職 稱講 師j2me和java領(lǐng)域1介紹20世紀(jì)70年代以來(lái)，隨著計(jì)算機(jī)革命的開(kāi)始，以及對(duì)計(jì)算機(jī)先進(jìn)軟件需求的大大增加，采取利用電腦日益增加的功能來(lái)處理數(shù)據(jù)。c編程語(yǔ)言逐漸成為支柱，使程序員開(kāi)發(fā)軟件可以像計(jì)算機(jī)運(yùn)行一樣流暢。80年代以來(lái)，程序員又目睹了編程語(yǔ)言領(lǐng)域的又一次變革的高潮。c語(yǔ)言的編程能力已經(jīng)不能滿足計(jì)算機(jī)的技術(shù)發(fā)展的需要。這問(wèn)題并不是新問(wèn)題。它造成了一代又一代的編程語(yǔ)言的新老更替。問(wèn)題是，它使得程序設(shè)計(jì)過(guò)于復(fù)雜，從而使計(jì)算機(jī)軟件的設(shè)計(jì)，編寫(xiě)和開(kāi)發(fā)落后于硬件的發(fā)展。就是這個(gè)時(shí)候，兩種基于設(shè)

2、計(jì)概念的編程語(yǔ)言simula 67和smalltalk（從上世紀(jì)60年代末）帶來(lái)了接近編程語(yǔ)言未來(lái)前景的循序漸進(jìn)的步驟。這期間，當(dāng)面向?qū)ο缶幊蹋╫op），并與它稱為一種新的編程語(yǔ)言c+在程序員中掀起了一場(chǎng)風(fēng)暴。1979年， bjarne stroustrup的在新澤西州的貝爾實(shí)驗(yàn)室增強(qiáng)了c 語(yǔ)言，使其具有面向?qū)ο蟮奶攸c(diǎn)，即所謂的c + + 語(yǔ)言 （ + +是c編程語(yǔ)言增強(qiáng)的承載符號(hào) ）。 c + +是一個(gè)真正的提高的c編程語(yǔ)言，它開(kāi)始是一種前置語(yǔ)言，該計(jì)劃最初是一種編譯工具。stroustrup建立類的概念（借用了simula 67和smalltalk中的概念），由類則可以創(chuàng)建實(shí)例對(duì)象。一個(gè)類

3、包含數(shù)據(jù)成員和定義對(duì)象數(shù)據(jù)和功能的成員函數(shù)。他還介紹了繼承的概念，使一類繼承其他一個(gè)或多個(gè)類的部分或全部數(shù)據(jù)成員或成員函數(shù)，職能由一個(gè)或多個(gè)其他類別-所有這些概念就是面向?qū)ο蟮木幊獭?988年由ansi官員將c+標(biāo)準(zhǔn)化。走進(jìn)java正當(dāng)c+作為企業(yè)開(kāi)發(fā)所選擇的語(yǔ)言時(shí)，由于最新的突破性技術(shù)-萬(wàn)維網(wǎng)的出現(xiàn)，另一種編程語(yǔ)言正在萌芽，并逐漸成熟。幾十年來(lái)互聯(lián)網(wǎng)對(duì)普通人來(lái)說(shuō)還是個(gè)秘密，直到前美國(guó)國(guó)家科學(xué)基金會(huì)（監(jiān)督互聯(lián)網(wǎng)的機(jī)構(gòu)）拆除了防止互聯(lián)網(wǎng)商業(yè)化的壁壘。1991年當(dāng)它向商貿(mào)開(kāi)放時(shí)，互聯(lián)網(wǎng)幾乎是政府機(jī)構(gòu)和學(xué)術(shù)團(tuán)體的專利。一旦商業(yè)化的障礙被取消，萬(wàn)維網(wǎng)提供的幾個(gè)服務(wù)，在互聯(lián)網(wǎng)上成為虛擬社區(qū)中心，游客可以

4、得到幾乎任何的免費(fèi)的資訊并瀏覽數(shù)以千計(jì)的虛擬商店。 瀏覽器加強(qiáng)了萬(wàn)維網(wǎng)。瀏覽器轉(zhuǎn)換將用html編寫(xiě)的ascii文本文件轉(zhuǎn)化成為一個(gè)互動(dòng)的顯示功能，并可以在任何計(jì)算機(jī)上編譯運(yùn)行。只要瀏覽器兼容的html和http實(shí)施正確的版本， 在任何電腦上運(yùn)行的瀏覽器可以使用相同的html文件，而不是指定為某一特定類型的計(jì)算機(jī)，而在以前是聞所未聞的。而c或c+是依賴于機(jī)器的，并且不能運(yùn)行于不同機(jī)器上，除非是重新編譯。互聯(lián)網(wǎng)的成功使人們將重點(diǎn)放在發(fā)展獨(dú)立于機(jī)器的編程語(yǔ)言上。和同年在互聯(lián)網(wǎng)上被商品化，科技工作者sunmicrosystems詹姆斯戈斯林，帕特里克諾頓， chriswarth ，和麥克謝里登花了18

5、個(gè)月發(fā)展規(guī)劃，并在1995年向公眾發(fā)布，他們所謂的oak，后來(lái)改名為java。java 在1991年和1995年期間經(jīng)歷了無(wú)數(shù)次的變革。那個(gè)時(shí)候，在sun公司的許多其他科技人員對(duì)該語(yǔ)言的發(fā)展做出了重大貢獻(xiàn)。joy，阿瑟范霍夫，喬納森佩恩，yelin， 添佩爾都分享了成功的喜悅。 雖然java是和互聯(lián)網(wǎng)密切相關(guān)，但開(kāi)始是為了開(kāi)發(fā)一種可以嵌入到電子器件中去的軟件的編程語(yǔ)言，而無(wú)論所用裝置的cpu類型。這也是眾所周知的所謂embedded java平臺(tái)。java團(tuán)隊(duì)從sun成功地建立了一種可移植性的編程語(yǔ)言，電腦程序員進(jìn)行了首次編程，一些已經(jīng)實(shí)現(xiàn)。他們的成功遠(yuǎn)遠(yuǎn)超出了他們的夢(mèng)想。同樣可以使java程

6、序進(jìn)行在各種可移植的電子裝置上，也可以使java程序在安裝了microsoft windows ，unix和macintosh的計(jì)算機(jī)上運(yùn)行。這個(gè)時(shí)機(jī)很完美。因特網(wǎng)/內(nèi)部網(wǎng)已使美國(guó)企業(yè)為符合公司成本效益，而開(kāi)發(fā)應(yīng)用于公司的可移植程序的興趣。java已被證明可以作為一種成功開(kāi)發(fā)與機(jī)器無(wú)關(guān)的應(yīng)用程序的編程語(yǔ)言。 java虛擬機(jī)寫(xiě)java程序和寫(xiě)c+程序是相似的，這程序員可以編寫(xiě)：含指示的源代碼，成為一個(gè)編輯器，或在一個(gè)綜合發(fā)展環(huán)境中對(duì)源代碼進(jìn)行編譯。不過(guò)，這也就是java和c+一部分的方式。該編譯和鏈接的過(guò)程中一個(gè)c+程序的結(jié)果可以運(yùn)行在一個(gè)適當(dāng)?shù)目蓤?zhí)行的機(jī)器上。與此相反，java編譯器則將jav

7、a 源代碼轉(zhuǎn)換成字節(jié)，即由java虛擬機(jī)（jvm）執(zhí)行 。機(jī)器的具體指示，則不會(huì)包括在字節(jié)中。相反，他們已經(jīng)包括在jvm的，這是屬于具體機(jī)器的。這意味著該字節(jié)可能包含的c+程序要翻譯的指令要少。未來(lái)的世界：j2me請(qǐng)記住，java是在消費(fèi)和工業(yè)產(chǎn)品中作為一種編程語(yǔ)言創(chuàng)建程序嵌入式系統(tǒng)微機(jī)發(fā)現(xiàn)的開(kāi)始，如那些用來(lái)控制汽車和家用電器的微機(jī)。在20世紀(jì)90年代初，開(kāi)發(fā)團(tuán)隊(duì)在sun的工作利用java以解決幼稚的嵌入式電腦市場(chǎng)的編程的需要，但這種努力是更側(cè)重于來(lái)自互聯(lián)網(wǎng)的吸引力的機(jī)會(huì)。在世紀(jì)交替之年由于這些機(jī)會(huì)已得到解決，一種新的便攜式通信帶來(lái)了其他設(shè)備的機(jī)會(huì)。從語(yǔ)音通信設(shè)備的語(yǔ)音到文本通信設(shè)備。而便攜式

8、電子電話簿演變成個(gè)人數(shù)碼助理。在這時(shí)候，芯片制造商所推出的新產(chǎn)品，其目的是為了從桌上型電腦轉(zhuǎn)移計(jì)算能力到移動(dòng)的小型電腦控制的燃?xì)馑?，電纜電視盒，和其他組合的其他電器。為下一步的演變的java的時(shí)機(jī)是合理的 。不過(guò)，不是java 與額外的空氣污染指數(shù)加強(qiáng)，在sun公司的該小組，即java community process計(jì)劃， 拆除均采用java編程語(yǔ)言和java虛擬機(jī)。他們從嵌入式系統(tǒng)和微機(jī)設(shè)備剝離下來(lái)的java的api和jvm到最低限度編碼須提供情報(bào)。由于這些設(shè)備資源方面的限制強(qiáng)加的硬件設(shè)計(jì)，這是必要的。他們的努力結(jié)果是j2me的。 j2me是減少了java api和java虛擬機(jī)是設(shè)計(jì)

9、用來(lái)運(yùn)作稀疏可用的資源在新的品種的嵌入式計(jì)算機(jī)和微機(jī)的版本。組織j2me傳統(tǒng)計(jì)算設(shè)備需要使用標(biāo)準(zhǔn)相當(dāng)?shù)挠布渲?，如顯示器，鍵盤(pán)，鼠標(biāo)和大量的記憶和永久儲(chǔ)存。不過(guò)，其中新一代的計(jì)算設(shè)備缺乏的硬件配置的連續(xù)性。有些設(shè)備不具有顯示屏，永久儲(chǔ)存，鍵盤(pán)， 或鼠標(biāo)。其中小的計(jì)算設(shè)備的記憶提供情況是不一致的。缺乏統(tǒng)一標(biāo)準(zhǔn)的硬件配置之間的小型計(jì)算設(shè)備的構(gòu)成是一項(xiàng)艱巨的挑戰(zhàn)java community process的計(jì)劃則是為jvm和j2me的小型計(jì)算設(shè)備制定標(biāo)準(zhǔn)。 許多不同種的小的j2me的計(jì)算設(shè)備，包括screen phones，數(shù)字機(jī)頂盒用于有線電視，手機(jī)和個(gè)人數(shù)字助理，所面臨的挑戰(zhàn)是java comm

10、unity process的計(jì)劃是建立一個(gè)可以對(duì)小的無(wú)標(biāo)準(zhǔn)的計(jì)算設(shè)備實(shí)施的java標(biāo)準(zhǔn)。j2me profile一個(gè)配置文件構(gòu)成的java類，其執(zhí)行的功能是為一特別小的計(jì)算裝置或一類的小型計(jì)算設(shè)備的。小型計(jì)算機(jī)技術(shù)不斷發(fā)展， j2me的配置文件的發(fā)展也是一個(gè)持續(xù)的過(guò)程。 配置文件已被界定為編寫(xiě)文本。這些即是foundation profile，game profile，midp，pda personal profile，personal profile，personal basis profile，和rmi personal profile。 基礎(chǔ)配置文件是用來(lái)做cdc和配置的，而這種配置文件

11、或cdc幾乎是所有其他的配置文件與cdc的核心，因?yàn)榕渲玫幕A(chǔ)個(gè)人資料包含核心的java類。 game profile也可以用來(lái)與cdc配置，并包括為開(kāi)發(fā)游戲申請(qǐng)任何一個(gè)小的計(jì)算設(shè)備的使用，和cdc的配置所必要的類。移動(dòng)信息設(shè)備配置文件（ midp）是用來(lái)與cldc 配置和包含的類別提供本地的存儲(chǔ)空間，用戶界面，和聯(lián)網(wǎng)能力，從而使應(yīng)用程序運(yùn)行在一個(gè)移動(dòng)計(jì)算裝置，例如palm os的設(shè)備。 midp即是使用無(wú)線java應(yīng)用程序。 pdaprofile（pdap）是用來(lái)實(shí)現(xiàn)cldc配置，并包含個(gè)人數(shù)字助理類所需要的先進(jìn)的資源。相對(duì)于midp的移動(dòng)設(shè)備（如手機(jī)），這些先進(jìn)的功能包括更好的顯示和較大的

12、內(nèi)存，比類似的資源。 personal profile是用來(lái)供cdc的配置和foundation profile(基礎(chǔ)配置文件)，并含有實(shí)現(xiàn)一項(xiàng)復(fù)雜的用戶界面類。personal profile提供的核心類，及personal提供一種類，用以實(shí)施一個(gè)先進(jìn)的用戶界面，也就是說(shuō)一個(gè)用戶界面，是能夠顯示多個(gè)窗口的。 personal basis profile是和personal profile類似的，因?yàn)樗怯脕?lái)為cdc配置的。然而，personal basis profile提供類所實(shí)施的一個(gè)簡(jiǎn)單的用戶界面，這是在一段時(shí)間內(nèi)用戶接口所在地能夠顯示的一個(gè)窗口。 隨著小型計(jì)算設(shè)備的繼續(xù)發(fā)展，有可能會(huì)

13、出現(xiàn)更多的文件。業(yè)集團(tuán)是java community process計(jì)劃（ / aboutjava / communityprocess ）定義的配置文件。該集團(tuán)各組確立了標(biāo)準(zhǔn)配置文件所使用的小型計(jì)算設(shè)備制造行業(yè)的標(biāo)準(zhǔn)。 acdc的personal profile是指通過(guò)擴(kuò)大后的核心java類中發(fā)現(xiàn)的專門(mén)針對(duì)一類的小型計(jì)算設(shè)備basis profile與類。這些裝置的具體類，裝載于一個(gè)新的配置文件中，使開(kāi)發(fā)人員能夠利用這些設(shè)備開(kāi)發(fā)一些應(yīng)用程序。但是，如果foundation profile 是特定cdc的，而不是所有的配置文件的，是在foundation person

14、al profile是擴(kuò)大后的核心類。請(qǐng)記住，應(yīng)用程序可以訪問(wèn)的一小型電腦設(shè)備的軟件和硬體功能，只有當(dāng)必要的類，這樣做是載于jvm和在配置文件所用的開(kāi)發(fā)的需要。j2me和無(wú)線設(shè)備隨著手機(jī)等無(wú)線設(shè)備的大量出現(xiàn)和功能的逐漸完善，對(duì)運(yùn)行在這樣的設(shè)備上的軟件的要求量也越來(lái)越大。消費(fèi)者和企業(yè)都要擴(kuò)大移動(dòng)通信設(shè)備的功能，使其從傳統(tǒng)的語(yǔ)音通信過(guò)渡到類似于筆記本電腦和個(gè)人電腦的功能，使他們可以傳送和接收電子郵件，存儲(chǔ)和檢索的個(gè)人資料，執(zhí)行精密的計(jì)算，和玩游戲。 開(kāi)發(fā)商，移動(dòng)通信設(shè)備制造商，和移動(dòng)網(wǎng)絡(luò)供應(yīng)商現(xiàn)正急欲填補(bǔ)這方面的需求，但有是一個(gè)嚴(yán)重的障礙：移動(dòng)通信設(shè)備利用許多不同的應(yīng)用平臺(tái)和經(jīng)營(yíng)調(diào)整代碼，為一設(shè)備

15、開(kāi)發(fā)的代碼將無(wú)法運(yùn)行在另一個(gè)設(shè)備上。移動(dòng)通信設(shè)備缺乏一個(gè)標(biāo)準(zhǔn)的應(yīng)用平臺(tái)及作業(yè)系統(tǒng)，這使得應(yīng)用開(kāi)發(fā)移動(dòng)通信設(shè)備，促進(jìn)經(jīng)濟(jì)發(fā)展有些冒險(xiǎn)。 缺乏標(biāo)準(zhǔn)，就是沒(méi)有新的計(jì)算或任何技術(shù)開(kāi)發(fā)。 在傳統(tǒng)意義上，硬件設(shè)備制造商的嘗試產(chǎn)品遍及市場(chǎng)，并執(zhí)行他們的自己的專有標(biāo)準(zhǔn)作為事實(shí)上的業(yè)界的標(biāo)準(zhǔn)。許多暴發(fā)戶成功的情況和微軟一樣。其他時(shí)候，業(yè)界領(lǐng)袖則組成一個(gè)財(cái)團(tuán)，例如java community process計(jì)劃，集體制定一種標(biāo)準(zhǔn)。 無(wú)線應(yīng)用協(xié)議（wap）行動(dòng)網(wǎng)際網(wǎng)路論壇成為初步創(chuàng)建無(wú)線技術(shù)標(biāo)準(zhǔn)的產(chǎn)業(yè)集團(tuán)。wap 論壇創(chuàng)造了移動(dòng)通信設(shè)備標(biāo)準(zhǔn)，被稱為thewap標(biāo)準(zhǔn)。 thewap標(biāo)準(zhǔn)是一個(gè)提高的html，xml的，

16、和tcp / ip 的一個(gè)組成部分，這個(gè)標(biāo)準(zhǔn)是無(wú)線標(biāo)記語(yǔ)言規(guī)范而組成的，融合了html和xml。wmlscript 是一種剝奪式版本的javascript。j2me applications j2me的應(yīng)用程序稱為midlet幾乎可以運(yùn)行在任何實(shí)現(xiàn)了jvm和midp移動(dòng)通信設(shè)備上。這鼓勵(lì)開(kāi)發(fā)商投資時(shí)間和金錢(qián)在建設(shè)移動(dòng)通信設(shè)備上，而不需要擔(dān)心該應(yīng)用是設(shè)備依賴的風(fēng)險(xiǎn)。不過(guò)，j2me是不會(huì)被視為更換為wap的規(guī)格，因?yàn)閮烧叨际腔パa(bǔ)的技術(shù)。開(kāi)發(fā)商的申請(qǐng)是根據(jù)客戶要求的基礎(chǔ)繼續(xù)使用wml和wmlscript 。開(kāi)發(fā)商轉(zhuǎn)向j2me的較重的客戶，需要對(duì)移動(dòng)通信設(shè)備進(jìn)行復(fù)雜的處理。 作者：邁克詹姆斯 java

17、 2 micro edition and the world of java1 introduction the computer revolution of the 1970s increased the demand for sophisticated computer software to take advantage of the ever-increasing capacity of computers to process data. the c programming language became the linchpin that enabled programmers t

18、o build software that was just as robust as the computer it ran on.as the 1980s approached, programmers were witnessing another spurt in the evolution of programming language. computer technology advanced beyond the capabilities of the c programming language. the problem wasnt new. it occurred previ

19、ously and caused the demise of generations of programming languages. the problem was that programs were becoming too complicated to design, write, and manage to keep up with the capabilities of computers. it was around this time that a design concept based on simula 67 and smalltalk (from the late 1

20、960s) moved programming to the next evolutionary step. this was the period when object-oriented programming (oop), and with it a new programming language called c+, took programmers by storm.in 1979, bjarne stroustrup of bell laboratories in new jersey enhanced the c programming language to include

21、object-oriented features. he called the language c+. (the + is the incremental operator in the c programming language.) c+ is truly an enhancement of the c programming language, and it began as a preprocessor language that was translated into c syntax before the program was processed by the compiler

22、.stroustrup built on the concept of a class (taken from simula 67 and smalltalk), from which instances of objects are created. a class contains data members and member functions that define an objects data and functionality. he also introduced the concept of inheritance, which enabled a class to inh

23、erit some or all data members and member functions from one or more other classesall of which complements the concepts of object-oriented programming. by 1988, ansi officials standardized stroustrups c+ specification.2 enter javajust as c+ was becoming the language of choice for building industrial-

24、strength applications, another growth spurt in the evolution of programming language was budding, fertilized by the latest disruptive technologythe world wide web. the internet had been a well-kept secret for decades before the national science foundation (who oversaw the internet) removed barriers

25、that prevented commercialization. until 1991 when it was opened to commerce, the internet was the almost exclusive domain of government agencies and the academic community. once the barrier to commercialization was lifted, the world wide webone of several services offered on the internet became a vi

26、rtual community center where visitors could get free information about practically anything and browse through thousands of virtual stores.browsers power the world wide web. a browser translates ascii text files written in html into an interactive display that can be interpreted on any machine. as l

27、ong as the browser is compatible with the correct version of html and http implementation, any computer running the browser can use the same html document without having to modify it for a particular type of computer, which was something unheard of at the time. programs written in c or c+ are machin

28、e dependent and cannot run on a different machine unless the program is recompiled. the success of the internet gave renewed focus to developing a machine-independent programming language. and the same year the internet was commercialized, five technologists at sun microsystems set out to do just th

29、at. james gosling, patrick naughton, chriswarth, ed frank, and mike sheridan spent 18 months developing the programming language they called oak, which was renamed java when this new language made its debut in 1995. java went through numerous iterations between 1991 and 1995, during which time many

30、other technologists at sun made substantial contributions to the language. these included bill joy, arthur van hoff, jonathan payne, frank yelin, and tim lindholm. although java is closely associated with the internet, it was developed as a language for programming software that could be embedded in

31、to electronic devices regardless of the type of cpu used by the device. this is known as the embedded java platform and is in continuous use today for closed systems.the java team from sun succeeded in creating a portable programming language, something that had eluded programmers since computers we

32、re first programmed. their success, however, was far beyond their wildest dreams. the same concept used to make java programs portable to electronic devices also could be used to make java programs run on computers running microsoft windows, unix, and macintosh. timing was perfect. the internet/intr

33、anet had whetted corporate americas appetite for cost-effective, portable programs that could replace mission-critical applications within the corporation. and java had proven itself as a programming language used to successfully develop machine-independent applications.3 java virtual machinewriting

34、 java programs is similar to writing c+ programs in that the programmer writes source code that contains instructions into an editor, or in an integrated development environment, and then the source code is compiled. however, thats where java and c+ part ways. the compiling and linking process of a

35、c+ program results in an executable that can be run on an appropriate machine. in contrast, the java compiler converts java source code into bytecode that is executed by the java virtual machine (jvm).machine-specific instructions are not included in bytecode. instead, they already reside in the jvm

36、, which is machine specific. this means that the bytecode might contain fewer instructions that need to be translated than a comparable c+ program.although the java compiler generates bytecode that must be interpreted by the jvm at run time, the number of instructions that need translation are usual

37、ly minimal and have already been optimized by the java compiler.4 back to the future: j2meremember that java began as a programming language to create programs for embedded systemsmicrocomputers found in consumer and industrial products such as those used to control automobiles and appliances. the d

38、evelopment team at sun worked on java in the early 1990s to address the programming needs of the fledgling embedded computer market, but that effort was sidetracked by more compelling opportunities presented by the internet.as those opportunities were addressed, a new breed of portable communication

39、s devices opened other opportunities at the turn of the century. cell phones expanded j 2 m e : the complete reference from voice communications devices to voice and text communications devices. pocket electronic telephone directories evolved into personal digital assistants. chipmakers were releasi

40、ng new products at this time that were designed to transfer computing power from a desktop computer into mobile small computers that controlled gas pumps, cable television boxes, and an assortment of other appliances.the time was right for the next evolution of java. however, instead of beefing up j

41、ava with additional apis, the team at sun, along with the java community process program, dismantled both the java programming language and the java virtual machine. they stripped down java apis and the jvm to the minimum coding required to provide intelligence to embedded systems and microcomputer

42、devices. this was necessary because of resource constraints imposed upon the hardware design of these devices. the result of their efforts is j2me. j2me is a reduced version of the java api and java virtual machine that is designed to operate within the sparse resources available in the new breed of

43、 embedded computers and microcomputers.5 how j2me is organized traditional computing devices use fairly standard hardware configurations such as a display, keyboard, mouse, and large amounts of memory and permanent storage. however, the new breed of computing devices lacks hardware configuration con

44、tinuity among devices. some devices dont have a display, permanent storage, keyboard, or mouse. and memory availability is inconsistent among small computing devices. the lack of uniform hardware configuration among the small computing devices poses a formidable challenge for the java community proc

45、ess program, which is charged with developing standards for the jvm and the j2me for small computing devices. j2me must service many different kinds of small computing devices, including screenphones, digital set-top boxes used for cable television, cell phones, and personal digital assistants. the

46、challenge for the java community process program is to develop a java standard that can be implemented on small computing devices that have nonstandard hardware configurations. the java community process program has used a twofold approach to addressing the needs of small computing devices. first, t

47、hey defined the java run-time environment and core classes that operate on each device. this is referred to as the configuration. a configuration defines the java virtual machine for a particular small computing device. there are two configurations, one for handheld devices and the other for plug-in

48、 devices. next, the java community process program defined a profile for categories of small computing devices. a profile consists of classes that enable developers to implement features found on a related group of small computing devices.6 j2me configurationsthere are two configurations for j2me as

49、 of this writing. these are connected limited device configuration (cldc) and the connected device configuration (cdc). the cldc is designed for 16-bit or 32-bit small computing devices with limited amounts of memory.cldc devices usually have between 160kb and 512kb of available memory and are batte

50、ry powered. they also use an inconsistent, small-bandwidth network wireless connection and may not have a user interface. cldc devices use the kjava virtual machine (kvm) implementation, which is a stripped-down version of the jvm. cldc devices include pagers, personal digital assistants, cell phone

51、s, dedicated terminals, and handheld consumer devices with between 128kb and 512kb of memory.cdc devices use a 32-bit architecture, have at least two megabytes of memory available, and implement a complete functional jvm. cdc devices include digital set-top boxes, home appliances, navigation systems

52、, point-of-sale terminals, and smart phones.7 j2me profilesa profile consists of java classes that enable implementation of features for either a particular small computing device or for a class of small computing devices. small computing technology continues to evolve, and with that, there is an on

53、going process of defining j2me profiles. seven profiles have been defined as of this writing. these are the foundation profile, game profile, mobile information device profile, pda profile, personal profile, personal basis profile, and rmi profile. the foundation profile is used with the cdc configu

54、ration and is the core for nearly all other profiles used with the cdc configuration because the foundation profile contains core java classes. the game profile is also used with the cdc configuration and contains the necessary classes for developing game applications for any small computing device

55、that uses the cdc configuration. the mobile information device profile (midp) is used with the cldc configuration and contains classes that provide local storage, a user interface, and networking capabilities to an application that runs on a mobile computing device such as palm os devices. midp is u

56、sed with wireless java applications. the pdaprofile (pdap) is used with the cldc configuration and contains classes that utilize sophisticated resources found on personal digital assistants. these features include better displays and larger memory than similar resources found on midp mobile devices

57、(such as cell phones). the personal profile is used with the cdc configuration and the foundation profile and contains classes to implement a complex user interface. the foundation profile provides core classes, and the personal profiles provide classes to implement a sophisticated user interface, w

58、hich is a user interface that is capable of displaying multiple windows at a time. the personal basis profile is similar to the personal profile in that it is used with the cdc configuration and the foundation profile. however, the personal basis profile provides classes to implement a simple user i

59、nterface, which is a user interface that is capable of displaying one window at a time.there will likely be many profiles as the proliferation of small computing devices ontinues. industry groups within the java community process program (/ boutjava/communityprocess) define profiles. each group establishes