java 毕业论文外文文献翻译

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1、AdvantagesofManagedCodeMicrosoftintermediatelanguageshareswithJavabytecodetheideathatitisalow-levellanguagewithasimplesyntax,whichcanbeveryquicklytranslatedintonativemachinecode.Havingthiswell-defineduniversalsyntaxforcodehassignificantadvantages.PlatformindependenceFirst,itmeans

2、thatthesamefilecontainingbytecodeinstructionscanbeplacedonanyplatform;atruntimethefinalstageofcompilationcanthenbeeasilyaccomplishedsothatthecodewillrunonthatparticularplatform.Inotherwords,bycompilingtoILweobtainplatformindependencefor.NET,inmuchthesamewayascompilingtoJavabyteco

3、degivesJavaplatformindependence.PerformanceimprovementILisactuallyabitmoreambitiousthanJavabytecode.ILisalwaysJust-In-Timecompiled(knownasJIT),whereasJavabytecodewasofteninterpreted.OneofthedisadvantagesofJavawasthat,onexecution,theprocessoftranslatingfromJavabytecodetonativeexec

4、utableresultedinalossofperformance.Insteadofcompilingtheentireapplicationinonego(whichcouldleadtoaslowstart-uptime),theJITcompilersimplycompileseachportionofcodeasitiscalled(just-in-time).Whencodehasbeencompiled.once,theresultantnativeexecutableisstoreduntiltheapplicationexits,so

5、thatitdoesnotneedtoberecompiledthenexttimethatportionofcodeisrun.Microsoftarguesthatthisprocessismoreefficientthancompilingtheentireapplicationcodeatthestart,becauseofthelikelihoodthatlargeportionsofanyapplicationcodewillnotactuallybeexecutedinanygivenrun.UsingtheJITcompiler,such

6、codewillneverbecompiled.ThisexplainswhywecanexpectthatexecutionofmanagedILcodewillbealmostasfastasexecutingnativemachinecode.Whatitdoesn’texplainiswhyMicrosoftexpectsthatwewillgetaperformanceimprovement.Thereasongivenforthisisthat,sincethefinalstageofcompilationtakesplaceatruntim

7、e,theJITcompilerwillknowexactlywhatprocessortypetheprogramwillrunon.Thismeansthatitcanoptimizethefinalexecutablecodetotakeadvantageofanyfeaturesorparticularmachinecodeinstructionsofferedbythatparticularprocessor.实际上，IL比Java字节代码的作用还要大。IL总是即时编译的(简称JIT)，而Java字节代码常常是解释型的，Java的一个缺点是，在

8、运行应用程序时，把Java字节代码转换为内部可执行代码的过程可可能导致性能的损失