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对于最新稳定版本,请使用Spring Framework 7.0.1! |
使用 JSR 330 标准注释
Spring 支持 JSR-330 标准注释(依赖注入)。那些 注释的扫描方式与春季注释相同。要使用它们,你需要 在你的职业路径中拥有相关的罐子。
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如果你用Maven,那
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依赖注入@Inject和@Named
而不是@Autowired,你可以使用@jakarta.注入。注入如下:
-
Java
-
Kotlin
import jakarta.inject.Inject;
public class SimpleMovieLister {
private MovieFinder movieFinder;
@Inject
public void setMovieFinder(MovieFinder movieFinder) {
this.movieFinder = movieFinder;
}
public void listMovies() {
this.movieFinder.findMovies(...);
// ...
}
}
import jakarta.inject.Inject
class SimpleMovieLister {
@Inject
lateinit var movieFinder: MovieFinder
fun listMovies() {
movieFinder.findMovies(...)
// ...
}
}
如同@Autowired,你可以使用@Inject在现场层面,方法层面
以及构造子-参数层级。此外,你可以声明你的注入点为提供商,允许按需访问短范围的豆子或懒惰访问
其他豆子通过Provider.get()叫。以下示例提供了
前述示例:
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Java
-
Kotlin
import jakarta.inject.Inject;
import jakarta.inject.Provider;
public class SimpleMovieLister {
private Provider<MovieFinder> movieFinder;
@Inject
public void setMovieFinder(Provider<MovieFinder> movieFinder) {
this.movieFinder = movieFinder;
}
public void listMovies() {
this.movieFinder.get().findMovies(...);
// ...
}
}
import jakarta.inject.Inject
class SimpleMovieLister {
@Inject
lateinit var movieFinder: Provider<MovieFinder>
fun listMovies() {
movieFinder.get().findMovies(...)
// ...
}
}
如果你想用一个限定名称来表示应注入的依赖,
你应该使用@Named注释,如下示例所示:
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Java
-
Kotlin
import jakarta.inject.Inject;
import jakarta.inject.Named;
public class SimpleMovieLister {
private MovieFinder movieFinder;
@Inject
public void setMovieFinder(@Named("main") MovieFinder movieFinder) {
this.movieFinder = movieFinder;
}
// ...
}
import jakarta.inject.Inject
import jakarta.inject.Named
class SimpleMovieLister {
private lateinit var movieFinder: MovieFinder
@Inject
fun setMovieFinder(@Named("main") movieFinder: MovieFinder) {
this.movieFinder = movieFinder
}
// ...
}
如同@Autowired,@Inject也可以与java.util.Optional或@Nullable.这在这里更适用,因为@Inject不具备
一个必填属性。以下两组示例展示了如何使用@Inject和@Nullable:
public class SimpleMovieLister {
@Inject
public void setMovieFinder(Optional<MovieFinder> movieFinder) {
// ...
}
}
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Java
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Kotlin
public class SimpleMovieLister {
@Inject
public void setMovieFinder(@Nullable MovieFinder movieFinder) {
// ...
}
}
class SimpleMovieLister {
@Inject
var movieFinder: MovieFinder? = null
}
@Named和@ManagedBean:标准等价物@Component注解
而不是@Component,你可以使用@jakarta.inject.named或jakarta.annotation.ManagedBean,
如下示例所示:
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Java
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Kotlin
import jakarta.inject.Inject;
import jakarta.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;
}
// ...
}
import jakarta.inject.Inject
import jakarta.inject.Named
@Named("movieListener") // @ManagedBean("movieListener") could be used as well
class SimpleMovieLister {
@Inject
lateinit var movieFinder: MovieFinder
// ...
}
它非常常见使用@Component但未指定组件名称。@Named也可以以类似的方式使用,如下示例所示:
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Java
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Kotlin
import jakarta.inject.Inject;
import jakarta.inject.Named;
@Named
public class SimpleMovieLister {
private MovieFinder movieFinder;
@Inject
public void setMovieFinder(MovieFinder movieFinder) {
this.movieFinder = movieFinder;
}
// ...
}
import jakarta.inject.Inject
import jakarta.inject.Named
@Named
class SimpleMovieLister {
@Inject
lateinit var movieFinder: MovieFinder
// ...
}
当你使用@Named或@ManagedBean,你可以在
与使用Spring注释时的方式完全相同,如下示例所示:
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Java
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Kotlin
@Configuration
@ComponentScan(basePackages = "org.example")
public class AppConfig {
// ...
}
@Configuration
@ComponentScan(basePackages = ["org.example"])
class AppConfig {
// ...
}
与@ComponentJSR-330@Named以及JSR-250@ManagedBean注释不可组合。你应该用Spring的刻板印象模型来建造
自定义组件注释。 |
JSR-330标准注释的局限性
当你使用标准注释时,你应该知道有些重要内容 功能不可用,如下表所示:
| Spring | 雅加达.inject.* | Jakarta.inject 限制 / 评论 |
|---|---|---|
@Autowired |
@Inject |
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@Component |
@Named / @ManagedBean |
JSR-330 不提供可组合模型,仅提供识别命名组件的方法。 |
@Scope(“单例”) |
@Singleton |
JSR-330的默认瞄准镜和Spring的类似 |
@Qualifier |
@Qualifier / @Named |
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@Value |
- |
无对应物 |
@Lazy |
- |
无对应物 |
ObjectFactory |
提供商 |
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