Java Patterns - What is Inversion Of Control and the Dependency Injection pattern?

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What is Inversion Of Control and the Dependency Injection pattern?

Total Answers and Comments: 2

Last Update: July 13, 2009 Asked by: manish_cs00

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Submitted by: PNVRKPrasad

Comment: Dependency Injection is more appropriate name than inversion of control.
Purpose: Achieving polymorphism more flexibly through different server classes
How: Allocating (Injecting) the actual concrete class1 (server) at run time to the class2 (client). Class1 has variations and the configuration file holds the information of which class needs to be injected. Class1 can be replaced by class1A through config file.
Ways: Injecting through class2's constructor, Setter method,..
Examples: Spring, PicoContainer, Avalon
Similar patterns: Service Locator
Final word: Most of the design patterns are there to handle polymorphism requirements. They do it in different ways. Key is to understand the underlying problem/purpose.

Above answer was rated as good by the following members:
bbwinston

January 31, 2008 16:57:57

jwhite1202

Member Since: January 2008 Contribution: 2

RE: What is Inversion Of Control and the Dependency Injection pattern?

Inversion Of Control (IoC) and Dependency Injection (DI) are concepts generally associated with the Spring Framework. The easiest way to think of Inversion Of Control is what Rod Johnson (founder of the Spring framework) calls the Hollywood Principal "don't call us we'll call you:. IoC uses interfaces to acquire and release resources a prime example being JDBC connections. This also part of the reason Spring works so well with Object/Relational Mapping (ORM) tools such as Hibernate iBatis and TopLink.

DI is a more specific version of IoC. DI pushes application dependencies at runtime. DI comes in several flavors in Spring:
1. Setter Injection - uses Java Bean setters (and getters) to get dependencies
2. Contructor Injection - dependencies come from constructor arguments
3. Method Injection - where the container is used to implement dependencies

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July 11, 2009 10:05:28

PNVRKPrasad

Member Since: July 2009 Contribution: 4

RE: What is Inversion Of Control and the Dependency Injection pattern?

Comment: Dependency Injection is more appropriate name than inversion of control.
Purpose: Achieving polymorphism more flexibly through different server classes
How: Allocating (Injecting) the actual concrete class1 (server) at run time to the class2 (client). Class1 has variations and the configuration file holds the information of which class needs to be injected. Class1 can be replaced by class1A through config file.
Ways: Injecting through class2's constructor Setter method ..
Examples: Spring PicoContainer Avalon
Similar patterns: Service Locator
Final word: Most of the design patterns are there to handle polymorphism requirements. They do it in different ways. Key is to understand the underlying problem/purpose.

Is this answer useful? Yes | No

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