SPRING interview Questions

Explain about PreparedStatementCreator?

PreparedStatementCreator is one of the most common used interfaces for writing data to database. The interface has one method createPreparedStatement().

 

PreparedStatement createPreparedStatement(Connection conn) throws SQLException;

 

When this interface is implemented, we should create and return a PreparedStatement from the Connection argument, and the exception handling is automatically taken care off. When this interface is implemented, another interface SqlProvider is also implemented which has a method calledgetSql() which is used to provide sql strings to JdbcTemplate.

 

Explain about BatchPreparedStatementSetter?

If the user what to update more than one row at a shot then he can go forBatchPreparedStatementSetter. This interface provides two methods

 

setValues(PreparedStatement ps, int i) throws SQLException; int getBatchSize();

The getBatchSize() tells the JdbcTemplate class how many statements to create. And this also determines how many times setValues() will be called.

 

Explain about RowCallbackHandler and why it is used?

In order to navigate through the records we generally go for ResultSet. But spring provides an interface that handles this entire burden and leaves the user to decide what to do with each row. The interface provided by spring is RowCallbackHandler. There is a method processRow() which needs to be implemented so that it is applicable for each and everyrow.

 

What is DelegatingVariableResolver?
Spring provides a custom JavaServer Faces VariableResolver implementation that extends the standard Java Server Faces managed beans mechanism which lets you use JSF and Spring together. This variable resolver is called as DelegatingVariableResolver

  How to integrate  Java Server Faces (JSF) with Spring?
 JSF and Spring do share some of the same features, most noticeably in the area of IOC services. By declaring JSF managed-beans in the faces-config.xml configuration file, you allow the FacesServlet to instantiate that bean at startup. Your JSF pages have access to these beans and all of their properties.We can integrate JSF and Spring in two ways:
–>DelegatingVariableResolver: Spring comes with a JSF variable resolver that lets you use JSF and Spring together.
<?xml version=”1.0″ encoding=”UTF-8″?>
<!DOCTYPE beans PUBLIC “-//SPRING//DTD BEAN//EN”
“http://www.springframework.org/dtd/spring-beans.dtd”>
<faces-config>
<application>
<variable-resolver>
org.springframework.web.jsf.DelegatingVariableResolver
</variable-resolver>
</application>
</faces-config>
The DelegatingVariableResolver will first delegate value lookups to the default resolver of the underlying JSF implementation, and then to Spring’s ‘business context’ WebApplicationContext. This allows one to easily inject dependencies into one’s JSF-managed beans.
–> FacesContextUtils:custom VariableResolver works well when mapping one’s properties to beans in faces-config.xml, but at times one may need to grab a bean explicitly. The FacesContextUtils class makes this easy. It is similar to WebApplicationContextUtils, except that it takes a FacesContext parameter rather than a ServletContext parameter.
ApplicationContext ctx = FacesContextUtils.getWebApplicationContext(FacesContext.getCurrentInstance());

 What is  Java Server Faces (JSF) - Spring integration mechanism?
 Spring provides a custom JavaServer Faces VariableResolver implementation that extends the standard JavaServer Faces managed beans mechanism. When asked to resolve a variable name, the following algorithm is performed:
Does a bean with the specified name already exist in some scope (request, session, application)? If so, return it
Is there a standard JavaServer Faces managed bean definition for this variable name? If so, invoke it in the usual way, and return the bean that was created.
Is there configuration information for this variable name in the Spring WebApplicationContext for this application? If so, use it to create and configure an instance, and return that instance to the caller.
If there is no managed bean or Spring definition for this variable name, return null instead.
BeanFactory also takes part in the life cycle of a bean, making calls to custom initialization and destruction methods.
As a result of this algorithm, you can transparently use either JavaServer Faces or Spring facilities to create beans on demand.

What is Significance of JSF- Spring integration ?
Spring - JSF integration is useful when an event handler wishes to explicitly invoke the bean factory to create beans on demand, such as a bean that encapsulates the business logic to be performed when a submit button is pressed.

How to integrate your Struts application with Spring?
To integrate your Struts application with Spring, we have two options:
Configure Spring to manage your Actions as beans, using the ContextLoaderPlugin, and set their dependencies in a Spring context file.
Subclass Spring’s ActionSupport classes and grab your Spring-managed beans explicitly using a getWebApplicationContext() method.

What are ORM’s Spring supports ?
Spring supports the following ORM’s :
–> Hibernate
–> iBatis
–> JPA (Java Persistence API)
–> TopLink
–> JDO (Java Data Objects)
–> OJB

How to integrate Spring and Hibernate ?

 Spring and Hibernate can integrate using Spring’s SessionFactory called LocalSessionFactory. The integration process is of 3 steps.
–> Configure Hibernate mappings.
–> Configure Hibernate properties.
–> Wire dependant object to SessionFactory.

What are the ways to access Hibernate using Spring ?
There are two ways to access Hibernate from Spring:
–> Through Hibernate Template.
–> Subclassing HibernateDaoSupport
–> Extending HibernateDaoSupport and Applying an AOP Interceptor

What are Bean scopes in Spring Framework ?
The Spring Framework supports exactly five scopes (of which three are available only if you are using a web-aware ApplicationContext). The scopes supported are listed below:
Scope and Description of the Bean scopes in Spring Framework.
–>singleton  : Scopes a single bean definition to a single object instance per Spring IoC container.
–>prototype  : Scopes a single bean definition to any number of object instances.
–>request  : Scopes a single bean definition to the lifecycle of a single HTTP request; that is each and every HTTP request will have its own instance of a bean created off the back of a single bean definition. Only valid in the context of a web-aware Spring ApplicationContext.
–>session  : Scopes a single bean definition to the lifecycle of a HTTP Session. Only valid in the context of a web-aware Spring ApplicationContext.
–>global session  : Scopes a single bean definition to the lifecycle of a global HTTP Session. Typically only valid when used in a portlet context. Only valid in the context of a web-aware Spring ApplicationContext.

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