• An abstract class may have constructors
• It is illegal to invoke the new operator on an abstract class
• An abstract class is allowed to have method implementations
• There is no restriction about the placement of abstract classes in a class hierarchy
• It is legal for an abstract class to implement an interface and implement one or more interface methods
• A well-encapsulated class must have all of its attributes marked private
• A well-encapsulated class must hide all internal methods.
• NOT all attributes require accessor or mutator methods

From: http://sitestree.com/?p=4936
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Post Data:2008-07-21 09:28:29

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• Your first EJB application
• Your second EJB application
• An online music store – using EJB 3.0

From: http://sitestree.com/?p=4935
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Post Data:2011-11-10 23:41:54

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• J2EE core design patterns: Click on a pattern rectangle to explore
• Data Access Object
• Transfer Object

From: http://sitestree.com/?p=4934
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Post Data:2007-06-04 16:27:01

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• Focused on annotations – reduces the number of classes and interfaces, eliminates the need for a deployment descriptor
• Encapsulation of environmental dependencies and JNDI access: annotations, dependency injection, simple lookup mechanism
• Simpler enterprise bean types
• session beans: business interface can be a plain Java interface
• session beans: no need for a home interface
• entity persistence: Java Persistence API.
• A query language for Java persistence
• session beans and message driven beans: an interceptor facility
• implementation of callback interfaces is not a must
• Java persistence API: provide object relational mapping, can replace Hibernate
• A POJO (Plain Old Java Object) programming model
• A lightweight ORM persistence framework
• Dependency injection
• Metadata annotations
• Configuration by exception
• Elimination of component interfaces
• Elimination of home interfaces
• Reduction of the use of checked exceptions

From: http://sitestree.com/?p=4932
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Post Data:2009-06-10 02:59:25

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• JSP Syntax : Quick Reference
• <a href='
• JSP Syntax : Quick Reference‘target=’new’>JSP Syntax : Quick Reference – 2
• JSP tutorial by Sun: Reference

From: http://sitestree.com/?p=4931
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Post Data:2013-04-10 19:14:41

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• JSP Specification
• Servlet Specification
• Java Enterprise javabeans Specifications

From: http://sitestree.com/?p=4930
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Post Data:2009-10-10 10:47:36

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• doGet() processes HEAD requests in the absence of a doHead() method
• Not the service() method but the methods that are called by the service method are better candidates for overriding
• HttpServlet supports GET, POST, DELETE, OPTIONS, and TRACE requests
• Retrieve a single value for a form parameter named “username”: String u = request.getParameter(“username”);, String u = request.getParameterValues(“username”)[0];
• java.util.Enumeration getHeaderNames() – retrieves the complete collection of request headers
• set the content type of a servlet response:
  response.setContentType(“text/html”);
  response.setHeader(“Content-Type”, “text/html”);
  response.addHeader(“Content-Type”, “text/html”);
• Servlet.destroy(): Servlets release resources: When called, the servlet container may not route other requests to that instance of the servlet: Servlet.destroy() may never be called
• The destroy() method, called by the web container when the servlet (or the web application) is being shutdown. This is a very good place to put the code to close related socket connection
• no guarantee on when the finalize() method will be called by the JVM
• The init() method is called by the web container before any HTTP requests are processed by the servlet. This is a good place to open a socket connection
• web.xml, JAR files, Class files, the deployment descriptor – are expected to be placed under WEB-INF directory
• A welcome file: used when a user requests a directory
• welcome files may be used at any directory level
• the default servlet is used to handle requests for specific files that exist in the webapp
• By default, the web container sends a 404 error back if the requested file does not exist
• Define a mime-mapping:pdfapplication/pdf
• WAR files are created using the jar command.
• A web application may be packaged into a WAR file for deployment, but it is not required.
• The files within the WEB-INF directory and the files within the META-INF directory of a WAR file must not be directly served as content by the container in response to a Web client’s request.
• A webapp can only have one web.xml file and all configuration must exist in that one file even if the Java class files exist in some other package
• String boundObjectName = getServletContext().getInitParameter(“com.example.BoundObj”);:returns a String if an initializathttp://www.justetc.net/knowledge/editArticlesNext.phphttp://www.justetc.net/knowledge/editArticlesNext.phpion parameter of that name exists in web.xml
• session.removeAttribute(“app.util.DataSource”);: removes a session attribute
• Servlet context listeners are notified when the context is ready to process requests and when it is about to be shut down
• HttpSession.setAttribute(String attributeName,Object value): method stores an object

From: http://sitestree.com/?p=4929
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Post Data:2008-09-09 09:45:43

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