Question

使用xml，我能够定义一个常见的xml文件，我可以在其中放置用于其他不同condig文件的common bean。我将我的配置移动到psring java config，如何使用java config实现这一点？

让我说我的公共课程为：

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

我希望将其用作

@Configuration
public class AConfig {

    @Bean
    public ABB abb(){
        ABB abb = new ABB();
        //TODO abb.set  ????
        return abb;
    }
}

缺少TODO部分，我想使用公共类中的a（）。这可能吗？

Answer 1

最简单的方法就是在这样的私人会员中“自动装配”：

@Configuration
public class AConfig {

    @Autowire
    private A myA;

    @Bean
    public ABB abb(){
        ABB abb = new ABB();
        abb.setA(myA);  // or MUCH better, make the A member of ABB private final and overload a construtor
        return abb;
    }
}

这样做的原因是AConfig也是一个Bean。它必须由Spring Bean Factory构建。施工结束后，将进行后期施工活动 - 其中一项是处理施工后注释，如Autowired。所以'myA'将在@Bean注释方法中使用之前设置。

Answer 2

来自@Import注释Javadoc：

 * <p>Provides functionality equivalent to the {@code <import/>} element in Spring XML.
 * Only supported for classes annotated with {@code @Configuration} or declaring at least
 * one {@link Bean @Bean} method, as well as {@link ImportSelector} and
 * {@link ImportBeanDefinitionRegistrar} implementations.
 *
 * <p>{@code @Bean} definitions declared in imported {@code @Configuration} classes
 * should be accessed by using {@link org.springframework.beans.factory.annotation.Autowired @Autowired}
 * injection. Either the bean itself can be autowired, or the configuration class instance
 * declaring the bean can be autowired. The latter approach allows for explicit,
 * IDE-friendly navigation between {@code @Configuration} class methods.
 *
 * <p>May be declared at the class level or as a meta-annotation.
 *
 * <p>If XML or other non-{@code @Configuration} bean definition resources need to be
 * imported, use {@link ImportResource @ImportResource}

我假设如果您导入@Configuration类本身，即“后一种方法”，那么您只需在导入的类上显式调用@Bean方法，例如

@Configuration
@Import(BarConfiguration.class)
public class FooConfiguration {

    @Autowired
    private BarConfiguration barConfiguration;

    @Bean 
    public Foo foo() {
       Foo foo = new Foo();
       foo.setBar(barConfiguration.bar());
       return foo;
    }
}

你如何使用类中另一个类的bean？

2 个答案: