基于jsp校園二手交易系統(tǒng)的設(shè)計與實現(xiàn)外文翻譯-文庫吧資料
2024-11-16 06:10本頁面
【正文】 ok many good ideas from Java, such as a clean programming language, a virtual machine, and garbage collection. But for whatever reasons, C also left some good stuff behind, in particular security and platform independence. If you are tied to Windows, C makes a lot of sense. But judging by the job ads, Java is still the language of choice for a majority of developers. is proprietary, and it should therefore be avoided. Sun Microsystems licenses Java to distributors and end users. Although Sun has ulti mate control over Java through the “Java Community Process,” they have involved many other panies in the development of language revisions and the design of new libraries. Source code for the virtual machine and the libraries has always been freely available, but only for inspection, not for modification and redistribution. Up to this point, Java has been “closed source, but playing nice.” is interpreted, so it is too slow for serious applications. In the early days of Java, the language was interpreted. Nowadays, except on “micro” platforms such as cell phones, the Java virtual machine uses a justintime piler. The“ hot spots” of your code will run just as fast in Java as they would in C++, and in some cases, they will run faster. Java does have some additional overhead over C++. Virtual machine startup time is slow, and Java GUIs are slower than their native counterparts because they are painted in a platformindependent manner. People have plained for years that Java applications are too slow. However, today’s puters are much faster than they were when these plaints started. A slow Java program will still run quite a bit better than those blazingly fast C++ programs did a few years ago. At this point, these plaints sound like sour grapes, and some detrac tors have instead started to plain that Java user interfaces are ugly rather than slow. Java programs run inside a web page. All Java applets run inside a web browser. That is the definition of an applet—a Java program running inside a browser. But most Java programs are standalone applications that run outside of a web browser. In fact, many Java programs run on web servers and produce the code for web pages. programs are a major security risk. is a simpler version of Java. JavaScript, a scripting language that can be used inside web pages, was invented by Netscape and originally called LiveScript. JavaScript has a syntax that is reminiscent of Java, but otherwise there are no relationships (except for the name, of course). A subset of JavaScript is standardized as ECMA262. JavaScript is more tightly integrated with browsers than Java applets are. In particular, a JavaScript program can modify the document that is being displayed, whereas an applet can only control the appearance of a limited area. Java, I can replace my puter with a $500 “Inter appliance.” When Java was first released, some people bet big that this was going to happen. Ever since the first edition of this book, we have believed it is absurd to think that home users are going to give up a powerful and convenient desktop for a limited machine with no local storage. We found the Javapowered work puter a plausible option for a “ zero administration initiative” to cut the costs of puter ownership in a business, but even that has not happened in a big way. On the other hand, Java has bee wi
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