Brief introduction of J2EE
Sun Microsystems, Inc. in 1996 launched a new pure object-oriented programming language, called Java. Java technology has become the software industry appears one of the most important technology, this platform has nothing to do with the emergence of the programming language, immediately set off a revolution in the software industry, the Internet is now the most popular programming language . Java is a way to explain through the implementation of the language, characterized as: a simple, object-oriented, not dependent on the structure of machines, with portability, robustness, security, and provided with a mechanism and the modern network The perfect combination of technology. At present, in accordance with the Sun Microsystems Web site (http://java.) announced the standards, depending on the Java language applications will be divided into three platforms:
Java 2 Platform Micro Edition as J2ME, Java 2 Platform Micro Edition. For the development of handheld computers, mobile phones and other mobile communications equipment for use on embedded systems.
Java 2 Platform Standard Edition as J2SE, Java 2 Platform Standard Edition. Mainly used for the development of general desktop applications.
Java 2 Platform Enterprise Edition called J2EE, Java 2 Enterprise Edition platform, To be used for rapid design, development, deployment and management of enterprise-class software system.
J2EE is to use Java to develop a set of extended enterprise norms, it provides component-based design, development, deployment and management of enterprise application solutions. J2EE standards must be based on the J2SE platform, which not only consolidated the Standard Edition of the many advantages, For example, "a compiler, run everywhere" cross-platform features, convenient and efficient database technology to provide seamless connectivity JDBC (Java Data Base Connectivity, Java database connectivity), in Internet applications to ensure data integrity of the security model and support multi - Threading technology, At the same time also against Servlet / JSP, EJB, JMS, JTS / JTA, JCAT and XML technology to provide a comprehensive support. J2EE has been able to establish a set of enterprise-class software application development, shorten the product development cycle structure of the standard system.
In fact, J2EE has become the industrial development of enterprise-class standards and mainstream platform. J2EE for the establishment of a high-availability, high scalability, easy maintenance of enterprise-class system provides the perfect mechanism and the framework model. In J2EE to provide the unified development platform, can greatly reduce development costs and the application of multi-storey complex, the need for high-availability, high security and high scalability software services and the lack of funding for businesses, J2EE the middle Integrated framework of the competent and fully meet their requirements. At the same time, J2EE itself with the comprehensive directory services support and a high degree of security mechanisms and efficient performance show, and many other advantages, for the smooth integration of enterprise application systems have played an enormous role.
J2EE-based enterprise applications, without any particular operating system, network environment, the shackles of hardware platforms.Applications can be developed and deployed in the heterogeneous environment, and to ensure that the system of portability. Therefore, as long as the J2EE development of a standardized system can be deployed to various operating system platforms and network platforms. J2EE as a long-term stable performance, enterprise-class applications platform, to protect 7 × 24 hours of uninterrupted services to meet customers, partners, the needs of enterprises is an ideal platform for the operation of Internet globalization is an inevitable requirement for the development of the objective. J2EE high scalability features in today's "on demand" (IBM Corporation to the end of 2002) the popularity of e-commerce strategies of the times, made an outstanding contribution. J2EE using load-balancing strategy, the system software and hardware resources to maximize utilization and performance, eliminate bottlenecks in the system. Allow the deployment of integrated multiple servers, and can be highly scalable systems, the preservation of existing enterprise IT assets to reduce repetitive investment in the future but also to meet the needs of business applications.
J2EE Technical
In J2EE platforms, including a large number of technology, in order to provide developers with more comprehensive support.
Servlet Technology    Servlet Web application development is the foundation. It is entirely in Java language development is the Java platform on the CGI technology. It runs on the server-side J2EE containers, with high efficiency, to dynamically load and dynamically generate Web pages. Servlet Specializes in process control and conduct of business, the expansion of services for enterprise development strategy tailored and flexible.
JSP technology      Its essence is still Servlet, only to create two different ways. JSP documents from HTML files, Java and JSP label procedures constitute a fragment. JSP will be the first through the analyzer generates the Servlet source files, and then compile this document Servlet running. JSP Servlet and, with very high operating efficiency.
JNDI technology   Java Naming and Directory Interface, as JNDI. J2EE application components are usually located in different physical address of the machine, so the need for a mechanism to facilitate client users to find and use J2EE components and enterprise system resources. In J2EE system, the use of JNDI technical positioning various objects, including EJB objects, database-driven targets, JDBC data source object and connect information, and other objects. JNDI functions for the application to provide a unified interface to complete the standard definition of directory operations, such as through the object properties to find the target and positioning.