js|web| Evaluation | Mainstream Jsp:java Server Page
What is the reason for JSP to appear? Java is having a hard time pushing developers, first of all because Java lacks broad support for mainstream systems, and there is a lack of direct reference to all platforms and technologies. At this time Java went to the various application layer of the positive, in their own good and not good at the field are out of the firm footsteps. One of the most exciting web technicians is the emergence of the Java servlet and the gradual maturation of the JSP, this step-by-step all let Java formally toward the Web development technology arena. Java leverages its Cross-platform technology to enable Java applications to be deployed quickly on a variety of platforms, and it can actually be written in one place and run everywhere. It has more use of this advantage, clever Java versatility, JSP ease of use, the speed of the servlet combination, using platform deployment techniques to effectively mask the speed of Java, so Java quickly in the Web developers to promote the members of the team. With the Java Bean, EJB, Java application Server, Java Transaction Server, such as the powerful background to the real mature application.
What kind of language is JSP? In fact, JSP is Java, but it is a special Java language, added a special engine, this engine will httpservlet some objects of this class automatically initialized for users to use, and users do not have to worry about the previous work. At the same time, the engine introduced a series of special syntax, such as <jsp:*, <%@ and so on, using these syntax to do some specific operations, such as referencing files, URL steering, JavaBean references and so on, these are the engine automatically help you complete the initialization of the work. We can view this engine as a JSP to the Java servlet Generator or translator, so that users do not have to face the complex servlet in the dozens of lines of code that have not yet begun to work. This is jsp--a Java servlet builder. Jsp->java Servlet code (. Java file)->java Runtime Bin code (. class file), which is why the first time we run the JSP, the CPU runs very high, It actually calls the JSP engine to generate the Java file, and then compiles it to the class file with Javac to execute it. At the same time also explained that after the first run, why is the speed of the reason, as long as the JSP file does not change where this operation will no longer be carried out (unless you delete the class file). So, Java has what JSP has what kind of function, and ASP, the real power of JSP is we can never see the end of!
1, a place to write anywhere to run. This is a programmer's dream, but also a former programmer's nightmare, in order to run between different platforms, so that many programmers line of rewrite code. At this point, Java has given me the perfect answer. It does better than PHP, and your code doesn't have to change anything except the system.
2, the system of multiple flat support. I've seen a consistent java servlet/jsp Web server/application Server on almost every platform ... The system allows you to develop in any environment, deploy the system in any environment, and expand in any environment. Compared to the limitations of asp/php is visible.
3, strong scalability. From only a small jar file can run servlet/jsp to multiple servers for cluster and load are horizontal, to multiple application transaction processing, message processing ... A server to countless servers, Java shows the vitality of a giant.
4, diverse and powerful development tool support. This is similar to the ASP, Java has a lot of very good development tools and have a lot of free to get, and many of them have been able to run smoothly under a variety of platforms. If you use them carefully, you will find that they are much more powerful than when you see them on your first side.
1, like the ASP, some of Java's advantages is its fatal problem. It is precisely because of the cross-platform capabilities, in order to extreme scalability, so greatly increased the complexity of the product. So, how many pieces does it need to expand, and how many of the products are in the Java system? So you want to see the JRE, JDK, JSDK, jswdk ..., in fact, as long as they are effectively paired together, they can produce a strong performance, inseparable, but for a beginner: "There is no mistake!" Is it necessary for me to run a JSP with so many messy things! ”
2, from the appearance of the first day from the opponents scold: "Slow as the old cow." Really, when I first ran my JSP, I thought that my machine had crashed and which process was going to kill! The first compilation, the operation for the user is really a nightmare, in development I often dream at night to see the Winnt Task Manager CPU grid when the whole green waiting to drop down the look and feel.
3, skill or skill. There must be a price to pay for a shortcoming. Java is running at a rate that uses the permanent memory of the class, so it is in some cases using more memory than the number of users is actually the "lowest performance price ratio." On the other hand, it also requires hard disk space to store a series of. Java and. class files and corresponding version files.
4, lack of systematic information. That may not be true, but Sun is doing very poorly at home, Java's capital molten-based in the domestic very few, until now I have not seen a JSP book in the bookstore, and the Java system is less and less discussion books, and Java-related books (Chinese version) to now but three digits. And take a look at a lot of the tools are still talking about Visual J + + or Java 1.1 such a year of second-hand.
Applicable to the crowd: have a strong learning ability and patience of developers. Low input but would like to have a greater ability to scale applications.
Applicable platform: ... (Too much but no more than one by one columns) application: Internet/intranet application System with high reliability application, internet/intranet and Client/server
Learning methods: Java DOC documents and a document in a Java site source code resources for the Internet (sorry everyone, really can not put forward a better proposal, and then there is everyone's ability and luck, and inetnet on the help of netizens)
Recommended development tools: Jbuilder/visual Age for Java (which I did not use, but someone strongly recommended)/sun Forte for Javakawa
Recommended development environment: Windows nt/windows 2000 development system JBuilder 3.5 (it can become a web Server, even no longer requires other tools) Tomcat 3.1JDK 1.3 (can not be installed) Access 2000/p II 266/ 128M ram/9g HD
Recommended application Environment (min): RedHat Linux 6.2/mysql 3.22/apache 1.3.12/tomcat 3.1/jdk 1.3beta/piii 500/512m ram/9g HD
Recommended application Environment (best): Solaris 8/sybase 11/iplanet Enterprise Web Server 4.1/jdk 1.3beta/sun Netra t1/1g ram/18g HD