• First Spring+Hibernate Application in IntelliJ

From: http://sitestree.com/?p=4926
Categories:Java Short Notes
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Post Data:2006-08-17 07:59:04

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• Requirements: JDK 1.4.2 (or above), Tomcat 5.0+, Ant 1.6.1+
• Also, you can use cygwin in windows to emulate linux like commands
• set JAVA_HOME, ANT_HOME, CATALINA_HOME environment variables – paths to the installed software
• Add to PATH: JAVA_HOME/bin, ANT_HOME/bin, CATALINA_HOME/bin
• You can start with the minimal application like struts-blanke.war or webapp-minimal that contains the basic files for struts and spring frameworks respectively. Or start with a equinox download from https://equinox.dev.java.net/files/documents/1901/5728/equinox-1.0.zip that will simplify strut-spring integration/switching. Download and unzip
• Make sure that the environment variables are set properly. Take a look at build.xml file. Check different sections like compile, distribution, ant-tomcat, help, database
• run ant new -Dapp.name=users from windows/linux/cygwin command prompt. It will create a new application with name users.
• Check the directory structure. It should look like as follows:
• under newly created users directory run commands like ant and check output. In build.xml, change default=”help” to default=”compile”, run ant again, run ant deploy, play with different ant commands
• if ant command shows error messages then you may need to change build.xml file as indicated. With equinox, you may face path error like {…}/common/lib or {…} lib
• If things don’t work right, check build.properties and modify the options if required. Play again
• Also, check tomcatTasks.properties file to see what classes are used for different ant commands (used in the build.xml file)
• Run ant list to check the services running. if the command fails, check that build.properties file contains right information. Make sure tomcat-users.xml file under the Tomcat installation directory has an entry for users as provided in the build.properties file
• Make sure, you are under the users directory
• run: ant deploy : the users application will be deployed under Tomcat. Check target name=deploy section in your build.xml file. You will see what actually happens in deployment (mostly copy)
• Using your browser, go to: http://localhost:8080/users/, you will see the interface of the users application
• Unit Test Persistence Layer
• Hibernate for persistence
• Hibernate relates Java Objects to database tables, makes CRUD (Create, Read, Update, Delete) very easy
• Spring + Hibernate: 75% code reduction than Hibernate alone: [ref:Internet, sourcebeat.com]
• Spring + Hibernate: removal of a ServiceLocator, removal of several DAOFactory classes, replace Hibernate’s checked exceptions with Spring’s runtime exceptions
• Before proceeding further, you may want to open the application using Eclipse. You can also use any editor to create Java files.
• Eclipse 3.3.2: How to open the project: File->new->project->java->java project->create project from existing source->identify the location and provide project name as users->you may want to switch to java perspectives.
• Click on build.xml file. Right click -> run as -> 2 Ant Build. If compilation fails: change basedir to the application directory. If it fails again check, tomcat directories and the directories mentioned in the build.xml files are the same. [you may not need /server in build.xml for tomcat 6.o]
• Check: build.xml -> right click -> Run As -> 3. Ant Build -> check that you selected the operation you want. If you want to deploy your application after compilation you need to select compile, deploy. Check what else apply. Or you can use the ant command [with options] from the command prompt
• Now Hibernate and Persistence again:

From: http://sitestree.com/?p=4924
Categories:Java Short Notes
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Post Data:2006-12-25 08:52:32

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• Open-sourced on February, 2003
• Layered J2EE application framework
• Inversion of Control (IoC): A Data Access Object (DAO) depends on a DataSource.
• Allows: code to interfaces
• Spring has classes to support Hibernate, Struts, and other frameworks
• According to many Java developers [ref:internet], J2EE patterns are sometimes cumbersome. Spring uses patterns but made everything simpler
• ServiceLocator -> to lookup Hibernate sessions. Spring Alternative: configure a SessionFactory
• Spring provides/supports good programming practices such as, coding to interfaces, reducing coupling, easy testability.
• But EJBs require to run EJB containers (WebLogic, JBoss, Websphere) to test them [testability problems inherent in EJBs] [as of 2005]
• Over the time EJB [EJB 3.0 ] has recovered some of the issues like testability, portability [ 1. EJB 2.0 has deployment descriptors but EJB 3.0 has no deployment descriptor, 2. In EJB 2.0 you have to write Home and Remote Interfaces But in EJB3.0 you do not need to write Home interfaces, 3. In EJB 3.0, all entities are identified with ‘@’, 4. In EJB 3.0 methods like ejbPassivate, ejbActivate, ejbLoad, ejbStore, etc. are not required, 5. EJB 3.0 is totally newly designed including the entity manager, 6. EJB 3.0 entity beans are just POJO, 7. No EJB container required to run, 8. EJB 3.0 supports Java Persistence API for all of its data needs, 9. No XMLDeployment Descriptors but annotations, 10. EJB 3.0 entity beans/JPA becomes local, 11. Queries are very flexible. Multiple levels of joins are enabled, 12. EJB 3.0 pluggable, security enabled ]
• Spring Criticisms [as of 2005]: It’s not an standard like EJBs, too heavyweight (though custom selection of modules/jars will help)
• How Spring works: Spring can configure applications using JavaBeans. A class can expose it’s dependency through setters, Spring can configure that dependency.
• Inversion of Control/Dependency Injection: Wiring dependent objects together through a container
• Spring Modules: Spring AOP (source level metadata), ORM (Hibernate, iBATIS, JDO support), Spring Web (WebApplicationContext, MultipartResolver, Web Utilities), DAO (Transaction Infrastructure, JDBC, DAO support), Context (ApplicationContext, UI Support, Validation, JNDI, EJB, Remoting support, Mail), MVC (Web Framework, Web Views, JSP, Velocity, Freemarker, PDF, Excel, XML/XSL)
• Spring advantage over J2EE: Reducing Coupling: It’s better not to tightly couple any application to a specific resource. In J2EE, for database operations typically an abstract Factory class (DAOFactory) is defined and a class is written for each specific implementation (DAOFactoryOracle). [J2EE Factory Pattern]. It creates additional issues such as managing dependencies of these factoried objects, handling Hibernate Session
• Spring approach: bind interfaces to implementations, configure everything in an XML file, and modify the XML file as required for switching, unit tests can be written without the knowledge of the implementation [great with Hibernate and iBATIS] p30. Define the bean in the applicationContext.xml file, and use it from your code through ClassPathXmlApplicationContext, get a reference to the bean using ClassPathXmlApplicationContext.getBean. You can change the class property in the bean definition to use a different implementation
• You can use Hibernate from Spring (ORM support). If you go through wrapping classes of Spring to provide Hibernate functionalities, you will not require to worry about (try, catch) checked exceptions that Hibernate usually throws

From: http://sitestree.com/?p=4923
Categories:Java Short Notes
Tags:
Post Data:2006-10-26 16:03:22

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