Use of Spring @Bean annotations

@Bean is a method-level annotation that is used primarily in @configuration annotated classes, or in @component annotated classes. The ID of the added bean is the method name

Defining beans

Here's an example from @configuration.

@Configuration  Public class AppConfig {    @Bean    public  transferservice transferservice () {        return  New  Transferserviceimpl ();    }}

This configuration is equivalent to the previous configuration in XML

< Beans >    <  ID= "Transferservice"  class= "Com.acme.TransferServiceImpl"/ ></beans>

Bean dependency

@bean can also rely on any number of other beans, and if transferservice relies on accountrepository, we can implement this dependency through the method parameters

@Configuration  Public class AppConfig {    @Bean    public  transferservice transferservice (accountrepository Accountrepository) {        returnnew  Transferserviceimpl (accountrepository);    }}

Accept the callback of the life cycle

Any bean defined using @bean can also perform a life-cycle callback function, similar to the @postconstruct and @PreDestroy method. Use the following

 Public classFoo { Public voidinit () {//initialization Logic    }} Public classBar { Public voidCleanup () {//Destruction Logic}} @Configuration Public classAppConfig {@Bean (Initmethod= "Init")     PublicFoo foo () {return NewFoo (); } @Bean (Destroymethod= "Cleanup")     PublicBar Bar () {return NewBar (); }}

By default the bean configured with Javaconfig, if there is a close or shutdown method, the method will be executed automatically when the bean is destroyed, and if you do not want to execute the method, add @bean (destroymethod= "") to prevent the departure destruction method

Specify the scope of the bean using @scope annotations

You can use @scope annotations to specify beans that are defined with @bean

@Configuration  Public class myconfiguration {    @Bean    @Scope ("prototype")    public  encryptor encryptor () {        // ...     }}

@Scope and Scoped-proxy

Spring provides a proxy for scope, you can set the @scope property Proxymode to specify, the default is scopedproxymode.no, You can specify that the default is Scopedproxymode.interfaces or the default is Scopedproxymode.target_class.
Here is a demo, it seems to be used (not understand this piece)

// An HTTP session-scoped Bean exposed as a proxy @Bean @sessionscope  Public userpreferences userpreferences () {    returnnew  userpreferences ();} @Bean public Service UserService () {    new  simpleuserservice ();     // a reference to the proxied userpreferences Bean     service.setuserpreferences (Userpreferences ());     return Service;}

Naming a custom Bean

By default, the Bean name and method name are the same, and you can use the Name property to specify

@Configuration  Public class AppConfig {    = "Myfoo")    public  foo foo () {        returnNew  Foo ();    }}

The Bean Alias

The name of the bean supports aliases, using the following methods

@Configuration  Public class AppConfig {    = {"DataSource", "Subsystema-datasource", "Subsystemb-datasource" })      public DataSource DataSource () {        //  Instantiate, configure and return DataSource beans ...     }}

Description of the Bean

Sometimes it is also useful to provide details about the bean, which can be used @Description to provide

@Configuration  Public class AppConfig {    @Bean    @Description ("provides a basic example of a Bean")    public Foo foo () {        returnnew  Foo ();    }}

Loaded from: https://www.cnblogs.com/feiyu127/p/7700090.html

Use of Spring @Bean annotations