IT Knowledge

Load an entity There are two forms to get an entity with the methods load()  or get(). public Category getCategory(Long catId) throws DataAccessException { return (Category) this.getSessionFactory().getCurrentSession() . load(Category.class, catId); } public Category getCategory(Long catId) throws DataAccessException { return (Category) this.getSessionFactory().getCurrentSession() . get(Category.class, catId); } The difference are: load() Throws an exception if there isn't any row. Has performane benefits. get() Return null  if there isn't any row. HibernateTemplate -  Using Parameters with  findByNamedParam In case of use only one parameter, you need the query, parameter name and the value . public List<ArtEntity> getArtworkInCategory(Long catId) throws DataAccessException { return this.getHibernateTemplate(). fi...

Implementation of the methods equals and hashCode. @Override public boolean equals(Object o) { if (this == o) return true; if (!(o instanceof Category)) return false; Category category = (Category) o; if (categoryName != null ? !categoryName.equals(category.categoryName) : category.categoryName != null) { return false; } else { return true; } } @Override public int hashCode() { return categoryName != null ? categoryName.hashCode() : 0; }

Hibernate annotations @Entity - To persist the class @Basic  - Customized the persistance as lazy mode or aspects @Transient  - Don't persist @Temporal  - To persist dates  Ex.  @Temporal(TemporalType.TIMESTAMP) @Table  - To use a different name from table Ex.  @Table(name = "HOGWASH") @Column  - To map a column with different name  @Column(name = "commentText") @Id  - Define attribute as primary key @GeneratedValue  - Use with @Id to create an identifier, by default AUTO. Ex  @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="COMMENT_ID_SEQ") to specify a different behavior @OneToMany - To establish the relation. Ex @OneToMany(orphanRemoval = true, cascade = { javax.persistence.CascadeType. ALL }) orphanRemoval - Delete any dereferenced javax.persistence.CascadeType - The eentity will be affected in any save/update @Cache - First try to find an instance in the cache, helpful for improve performance Ex. @Cac...

There are two way to declare the configuration file You can declare the file with the configuration in the tag <init-param>    <servlet>       <servlet-name>galleryDispatcher</servlet-name>       <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>        <init-param>         <param-name>contextConfigLocation</param-name>         <param-value>                   /WEB-INF/spring/spring-master-web.xml               </param-value>       </init-param>       <load-on-startup>1</load-on-startup>     </servlet>  The second form is creating a file named  galleryDispatcher-servlet.xml in WEF-INF/.  In...

@Repository  annotation should be used to indicate those classes that compose the DAO layer. @Service  annotation can be used to designate those classes that are part of an application's service facade,  which are used in the web layer to handle requests @Controller  annotation denotes the presence of a POJO that should be used for Spring MVC interactions. D efines a service facade.

(application-context.xml) In your application-context.xml, use the tag  context:property-placeholder to define the property file where you have the values of your bean properties. The value of  location  is the rath of your file: <context:property-placeholder location ="classpath*:spring/*.properties" /> In case that you have your property file outside your project: <context:property-placeholder   location =" " file: ///var/conf/conf.properties"/> After define your file properties with the values: db.name = test db.user = user db.password = password db.port = 3306 Finally you can use the properties in your beans: <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> <property name="driverClassName" value="com.mysql.jdbc.Driver" /> <property name="url" value="jdbc:mysql://localhost:3306/test" /> <property name="usern...

In Eclipse to add the structure folders choose New -> Soure Folder Select the chech box "Update exclusion filters into other source folders to solve nesting" Within the  project_name  folder, we'll create the folders that are customary for a Java application: project_name /src project_name /src/main project_name /src/main/java project_name /src/main/resources For web applications, we need a   webapp   and   WEB-INF   folder: project_name /src/main/webapp project_name /src/main/webapp/WEB-INF We also need to create the folders that are required for unit testing our application: project_name /src/test project_name /src/test/java project_name /src/test/resources And finally, we'll create the two folders where Spring configuration files are ordinarily placed: project_name /src/main/webapp/WEB-INF/spring