spring

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@Configuration
public class AppConfig {
    @Bean
    public TransferService transferService(AccountRepository accountRepository) {
        return new TransferServiceImpl(accountRepository);
    }
}

public class Foo {
    public void init() {
        // initialization logic
    }
}

public class Bar {
    public void cleanup() {
        // destruction logic
    }
}

@Configuration
public class AppConfig {

    @Bean(initMethod = "init")
    public Foo foo() {
        return new Foo();
    }

    @Bean(destroyMethod = "cleanup")
    public Bar bar() {
        return new Bar();
    }

}
#### 自定义Bean命名

默认情况下，配置类使用@Bean方法的名称作为生成的bean的名称。但是，可以使用name属性来重写此功能。

@Configuration
public class AppConfig {

    @Bean(name = "myFoo")
    public Foo foo() {
        return new Foo();
    }

}

Bean别名

@Configuration
public class AppConfig {
    @Bean(name = { "dataSource", "subsystemA-dataSource", "subsystemB-dataSource" })
    public DataSource dataSource() {
        // instantiate, configure and return DataSource bean...
    }
}

Bean描述

@Configuration
public class AppConfig {
    @Bean
    @Description("Provides a basic example of a bean")
    public Foo foo() {
        return new Foo();
    }
}

@Configuration注解

@Configuration是一个类级别的注解，指明此对象是bean定义的源。@Configuration类通过public @Bean注解的方法来声明bean。在@Configuration类上对@Bean方法的调用也可以用于定义bean之间的依赖

@Configuration
public class AppConfig {

    @Bean
    public ClientService clientService1() {
        ClientServiceImpl clientService = new ClientServiceImpl();
        clientService.setClientDao(clientDao());
        return clientService;
    }

    @Bean
    public ClientService clientService2() {
        ClientServiceImpl clientService = new ClientServiceImpl();
        clientService.setClientDao(clientDao());
        return clientService;
    }

    @Bean
    public ClientDao clientDao() {
        return new ClientDaoImpl();
    }

}

clientDao()方法clientService1()和clientService2()被各自调用了一次,但ClientDao 只会有一个。
因为所有的@Configuration类在启动时都使用CGLIB进行子类实例化(配置类都不能是final类型),在子类中，子方法在调用父方法创建一个新的实例之前会首先检查任何缓存(作用域)的bean。

基于java组合配置

使用@Import注解

@Configuration
public class ConfigA {

    @Bean
    public A a() {
        return new A();
    }

}

@Configuration
@Import(ConfigA.class)
public class ConfigB {

    @Bean
    public B b() {
        return new B();
    }

}

public static void main(String[] args) {
    //只需引入ConfigB
    ApplicationContext ctx = new AnnotationConfigApplicationContext(ConfigB.class);
    // now both beans A and B will be available...
    A a = ctx.getBean(A.class);
    B b = ctx.getBean(B.class);
}

web.xml


 
        dispatcher
        org.springframework.web.servlet.DispatcherServlet
   .......

bean生命周期回调

class Foo implements  InitializingBean,DisposableBean,*Aware系列的接口{
     public void init() {
        // initialization logic
    }
}

@Configuration
public class AppConfig {

    @Bean(initMethod = "init")
 public Foo foo() {
        return new Foo();
    }

profile

-Dspring.profiles.active="profile1,profile2"

@Configuration
@Profile("default")
public class DefaultDataConfig {

    @Bean
    public DataSource dataSource() {
        return new EmbeddedDatabaseBuilder()
            .setType(EmbeddedDatabaseType.HSQL)
            .addScript("classpath:com/bank/config/sql/schema.sql")
            .build();
    }
}

@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Conditional(ProfileCondition.class)
public @interface Profile {

@EnableLoadTimeWeaving?