Hibernate has provided 3 ways to retreive the multiple records:

1. HQL
2. Criteria API
3. Native SQL

HQL:

SQL HQL

select * from employee; from Employee

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Spring AOP:

AOP(Aspect Oriented Programming):

-It is programming technique that separetes system services(concerns) from the business logic.

-System Services(Concerns) like logging , transaction management, excpetions, security ,encoding,decoding,,,,etc... -This system services are commonly referred to as "cross cutting concerns"

-Business logic which follow the business rules which is given by the client.

Cross-Cutting Concerns:

We can Move additional services of a project into the other classes (Services class/Aspect) and bind when ever we required.

Aspect:

• Aspect is a class that provides additional services to the project like (transaction management, logging,security,encoding and deconding etc..)
• Aspect is system services(transaction management, logging,security,encoding and deconding etc..) which is written in sepearte class.

Advice:

• Is a implementation of Aspect.
• It is a method inside the Aspect class.
• It define the job that an aspect will perform i.e advice defines both what and when of an aspect.

Pointcut:

• It is expression, it will select ref.method which needs advices.
• it can never specify what advices.

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Advice Type descritption

Before -Called before target method is invoked.

After -Called after target method return regardless of the outcome.

Around -Called after target and before target method.

After-returning -Called after target methods completes successfully

After-throwing -Called when target method throws an expection

Excution Flow:

adviceMethod() - first execute
bLMethod()     - second execute

After -Called after target method returns regardless of the outcome.

Excution Flow:

bLMethod()     - first execute
adviceMethod() - second execute

Around -Both Before and After target method executed.

Excution Flow:

adviceMethod() - first execute
    blMethod()     - second execute
adviceMethod() - third execute

After-returning -Called after target completes successfully.

Excution Flow:

    After excuting the blMethod() only on successfully compleation then only
           execute  the  adviceMethod()

After-throwing -Called when target method throws an exception

Excution Flow:

    After excuting the blMethod() if blMethod() is throwing the exception then
     execute the adviceMethod()

Target:

• The target class is a busniess component which is being advised.
• It is pure business logic class which is having BL but without services(logging,exception,.....)

Proxy:

A proxy is the object at runtime after applying advices to the target object.

joinpoint:

• The point where services is merged is called as joinpoint

Pointcut:

• A pointcut defines at what joinpoints advice should be applied.
• It is an expression language of AOP that matches joinpoints.
• It is an expression , it will select blMethod() which needs advices.

syntax:

AccessSpecifier/modifer RetunType Package.className.MethodName(Arguments)

eg: public void com.cgi.main.dao.EmployeeDAO.saveEmployee(Employee emp)

public * *() 

 -zero arguments, any  method name and any return type.

2. public void *(..)

   -It indicate two dots any no of/types of arguments, -Any method name -return type as void only -public as access modifier

3. public * com.cgi.dao.EmployeeDAO.*(..)

   -It indicate two dots i.e any no of types arguments,

   • Any method name which is define inside the com.cgi.dao.EmployeeDAO package -Any return type -public as access modifier

4. public * com.cgi.main..(..)

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