What is autowiring in Spring

                    What is autowiring   ?

Autowairing:-

Auto wiring means automatically injecting the dependencies. (Implicit Dependency Injection)

Insead of manually configuring (Explicit DIO) the injection we can do automatically by using autowiring.

To implements autowiring we use “autowire” attribute in<bean> tag configuration.

To perform autowiring for a particular bean we can use any one of the following values.

Types of Autowiring:-

            a)      byName

            b)     byType

            c)      constructor

            d)     autodetect

By using autowire attribute auto wiring is possible only on reference type bean prototypes that mean auto wiring is not possible on simple collection framework type properties.

Auto wiring kills the readability of spring configuration file.

     

byName:-

Mainly it checks for three conditions if all these ate valid then it injects the values by setter approach

       

           1.       dependency bean name

           2.       configured bean name

           3.       setter method name

è it dependency name is abc,bean configuration shoud be abc and the setter name method shoud i.e setAbc(Abc abc)

è when it finds autowire=”byName” for any bean confuguratin the it first checks for dependency bean nam in the dependent bean.

è Then it will checks weathdr any bean is configured in the sprng  cfg file with the same name.

è If it finds then it will call corresponding setter method of dependent bean.

byType :-

Mainly it checks for three conditions if all these are valid then it injects the values by setter approach

       

           1.       Dependency bean name

           2.       configured bean name

            3.       setter method argument type

è When it finds “autowire=”byType” for any bean configuration then it first checks for dependency bean type in the dependent bean then after it will checks weather any bean is configured in the spring cfg file with the same type. If it find then it will call corresponding setter method.

Constructors:-

Mainly it checks for three conditions if all these are valid then it injects the values by setter approach

1.       Dependency bean name

2.       configured bean name

3.       constructor argument type

è When it finds “autowire=” constructor” for any bean configuration then it first checks for dependency bean type in the dependent bean then after it will checks weather any bean is configured in the spring cfg file

è Weather any bean is configured with the type. If it finds check for constructor

è Which will talks dependency type if it finds it will check for constructor.