計算機外文翻譯---j2me和java領域-其他專業(yè)-全文預覽
【正文】 the JAVA piler generates bytecode that must be interpreted by theJVMat run time, the number of instructions that need translation are usually minimal andhave already been optimized by the JAVA Back to the Future: J2ME Remember that JAVA began as a programming language to create programs for embedded systems— microputers found in consumer and industrial products such as those used to control automobiles and appliances. The development team at SUNworked on JAVA in the early 1990s to address the programming needs of the fledgling embedded puter market, but that effort was sidetracked by more pelling opportunities presented by the Inter. As those opportunities were addressed, a new breed of portable municationsdevices opened other opportunities at the turn of the century. Cell phones expanded 4 J2ME The CompleteReference from voice munications devices to voice and text munications devices. Pocket electronic telephone directories evolvedinto personal digital assistants. Chipmakers were releasing new products at this time that weredesigned to transfer puting power from a desktop puter intomobile small puters 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 JAVA with additional APIs, the team at SUN, along with the JAVA munity process Program, dismantled both the JAVA programming language and the JAVAVirtual Machine. Theystripped down JAVA APIs and the JVM to the minimum coding required to provideintelligence to embedded systems and microputer devices. This was necessary because of resource constraints imposed upon the hardwaredesign of these devices. Theresult of their efforts is J2ME. J2ME is a reduced version of the JAVA API and JAVA Virtual Machine that is designed to operate withinthe sparse resources available in the new breed of embedded puters and microputers. 5 How J2ME Is Organized Traditional puting devices use fairly standard hardware configurations such as a display, keyboard,mouse, and large amounts of memory and permanent ver, the new breed of puting devices lacks hardware configuration continuity among devices. Some devices don’t have a display, permanent storage, keyboard,or mouse. And memory availability is inconsistent among small puting devices. The lack of uniform hardware configuration among the small puting devices poses a formidable challenge for the JAVA munity process Program,which is chargedwith developing standards for the JVM and the J2ME for smallputing devices. J2ME must service many different kinds of small puting devices, includingscreenphones, digital settop boxes used for cable television, cell phones, and personal digital assistants. The challenge for the JAVA munity process Program is to develop a JAVA standard that can be implemented on small puting devices that have nonstandard hardware configurations. The JAVA munity process Program has used a twofold approach to addressing the needs of small puting devices. First, they defined the JAVA runtime 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 puting device. There are two configurations, one for handheld devices and the othe
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