(3) a strong scalability. From only a small Jar documents can run Servlet / JSP, to the multiple servers clustering and load balancing, to multiple Application for transaction processing, information processing, a server to numerous servers, Java shows a tremendous Vitality.
(4) diversification and powerful development tools support. This is similar to the ASP, Java already have many very good development tools, and many can be free, and many of them have been able to run on a variety of platforms under.
JSP technology vulnerable
(1) and the same ASP, Java is the advantage of some of its fatal problem. It is precisely because in order to cross-platform functionality, in order to extreme stretching capacity, greatly increasing the complexity of the product.
(2) Java's speed is class to complete the permanent memory, so in some cases by the use of memory compared to the number of users is indeed a "minimum cost performance." On the other hand, it also needs disk space to store a series of. Java documents and. Class, as well as the corresponding versions of documents.
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JSP six built-in objects:
request, response, out, session, application, config, pagecontext, page, exception.
1. Request for:
The object of the package of information submitted by users, by calling the object corresponding way to access the information package, namely the use of the target users can access the information.
2. Response object:
The customer's request dynamic response to the client sent the data.
三. session object
1. What is the session: session object is a built-in objects JSP, it in the first JSP pages loaded automatically create, complete the conversation of management.
From a customer to open a browser and connect to the server, to close the browser, leaving the end of this server, known as a conversation. When a customer visits a server, the server may be a few pages link between repeatedly, repeatedly refresh a page, the server should be through some kind of way to know this is the same client, which requires session object.