The IoC Container 1.11

1.11. Using JSR 330 Standard Annotations

Spring支持JSR 330的注解，如果想使用，需要引入下面的包：

<dependency>
    <groupId>javax.inject</groupId>
    <artifactId>javax.inject</artifactId>
    <version>1</version>
</dependency>

1.11.1. Dependency Injection with @Inject and @Named
@javax.inject.Inject用来替换@Autowired：

import javax.inject.Inject;

public class SimpleMovieLister {

    private MovieFinder movieFinder;

    @Inject
    public void setMovieFinder(MovieFinder movieFinder) {
        this.movieFinder = movieFinder;
    }

    public void listMovies() {
        this.movieFinder.findMovies(...);
        ...
    }
}

@Inject can also be used with java.util.Optional or @Nullable：

public class SimpleMovieLister {

    @Inject
    public void setMovieFinder(Optional<MovieFinder> movieFinder) {
        ...
    }
}

public class SimpleMovieLister {

    @Inject
    public void setMovieFinder(@Nullable MovieFinder movieFinder) {
        ...
    }
}

@Named可以用来指定bean name，Spring就会按照bean的名称进行查找：

import javax.inject.Inject;
import javax.inject.Named;

public class SimpleMovieLister {

    private MovieFinder movieFinder;

    @Inject
    public void setMovieFinder(@Named("main") MovieFinder movieFinder) {
        this.movieFinder = movieFinder;
    }

    // ...
}

1.11.2. @Named and @ManagedBean: Standard Equivalents to the @Component Annotation

可以用@Named和@ManagedBean代替@Component：

import javax.inject.Inject;
import javax.inject.Named;

@Named("movieListener")  // @ManagedBean("movieListener") could be used as well
public class SimpleMovieLister {

    private MovieFinder movieFinder;

    @Inject
    public void setMovieFinder(MovieFinder movieFinder) {
        this.movieFinder = movieFinder;
    }

    // ...
}

@Named也可以和@Component一样不指定参数：

import javax.inject.Inject;
import javax.inject.Named;

@Named
public class SimpleMovieLister {

    private MovieFinder movieFinder;

    @Inject
    public void setMovieFinder(MovieFinder movieFinder) {
        this.movieFinder = movieFinder;
    }

    // ...
}

组件扫描的配置方式跟之前一致：

@Configuration
@ComponentScan(basePackages = "org.example")
public class AppConfig  {
    ...
}

1.11.3. Limitations of JSR-330 Standard Annotations

JSR-330注解的限制