Java noun annotations

1,Jvm:java virtual machine (Java VM), a very important feature of the Java language is the independence of the platform. The use of Java virtual machines is the key to achieving this feature. General high-level languages if you want to run on a different platform, you need to compile at least a different target code. When the Java language virtual machine is introduced, the Java language does not need to be recompiled when it runs on different platforms. The Java language uses a Java Virtual machine to mask information related to a specific platform, allowing the Java language compiler to generate only the target code (bytecode) that runs on a Java virtual machine, which can be run unmodified on multiple platforms. When a Java virtual machine executes a bytecode, it interprets the bytecode as a machine instruction execution on a specific platform. This is why Java can be "compiled once and run Everywhere".

2,Jer:java Runtime Environment (Java Runtime Environment), that is, the Java platform. All Java programs must be run under the JRE. Ordinary users only need to run the developed Java program, install the JRE.

3,Jdk:java Development Kit (Java language Software Development Kit), mainly for mobile devices, embedded devices on the Java application. The JDK is the core of the entire Java development, which contains Java's runtime environment, Java tools, and Java-based class libraries. If you do not have a JDK, you cannot compile the Java program, and if you want to run only Java programs, make sure that the appropriate JRE is installed.

4.Jbpm:java Business Process Management, which is an open-source, flexible and extensible executable process language framework covering business process management, workflow, and service collaboration. JBPM is a public source project that uses it to follow the ASL (Apache License Version 2.0) and the EULA (JBoss End User License Agreement) protocol.

5,b/s:browser/server (Browser/server mode), in this structure, the user interface is implemented through the WWW browser, very few transaction logic in the front end (Browser) implementation, but the main transaction logic on the server side (server ) to form a so-called three-layer 3-tier structure. b/S structure is a network structure model after the rise of web, Web browser is the main application software of the client. This mode unifies the client, and the core part of the system function is centralized to the server, which simplifies the development, maintenance and use of the system. As long as the client installs a browser (Browser), such as Netscape Navigator or Internet Explorer, the server installs databases such as Oracle, Sybase, Informix, or SQL Server. The browser interacts with the database through the Web server. This greatly simplifies the client computer load, reduces the cost and effort of system maintenance and upgrade, and reduces the total cost of users (TCO).

6, three layer architecture (3-tier architecture):

(1) The presentation layer (Usl-user show layers): The main means of the web, or can be expressed as WinForm way. If the logical layer is quite powerful and complete, the logic layer can provide services perfectly, regardless of how the presentation layer is defined and changed.

(2) business logic layers (bll-business logic layer): If the operation of the specific problem can also be understood as the operation of the data layer, the data business logic processing. If the data layer is a building block, the logical layer is the building blocks.

(3) The data Access layer (Dal-data access layers) is also known as the Persistence layer : The transaction of the layer directly manipulate the database, for the data to add, delete, modify, find and so on.

7.Jsp:java Server Pages (Java server Page), which is essentially a simplified servlet design, is a technology that enables software developers to dynamically generate Web pages for HTML, XML, or other format documents in response to client requests.

Nine large built-in objects:

Request requests Object HttpServletRequest scope request

Response Response Object Httpsrvletresponse scope Page

PageContext page Context Object PageContext scope page

Session conversation Object HttpSession scope session

Application Application Object ServletContext scope application

Out output Object JspWriter scope Page

Config configuration object ServletConfig scope Page

Page objects Object Scope pages

Exception exception Object Jspexception Scope page

　　

Four scopes:

Application is valid in all applications, the server boots to shutdown for the entire period of time, the information set within this scope can be used by all applications

Sessions are valid in the current session and are typically 30 minutes in duration.

Request is valid in the current request, the processing of an HTTP request may require multiple servlets to work together, and these servlets can pass information in some way, but this information is not valid after the request has been completed.

Page is valid on the current page, and a reference to the Page object is freed after the response is returned to the client, or after the request is forwarded to another location. References to page objects are typically stored in the PageContext object.

　Note: Cookies do not recommend the use of JSP built-in objects to operate, this belongs to the front-end, with jquery operation.

8.Jdbc:java Data Base Connectivity (Java database connection)is a Java API for executing SQL statements that provides unified access to a variety of relational databases, consisting of a set of classes and interfaces written in the Java language. JDBC provides a benchmark to build more advanced tools and interfaces that enable database developers to write database applications.

Java noun annotations