java 没有自动装配注释的弹簧注入
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Spring inject without autowire annotation
提问by kuba44
I find some answer: https://stackoverflow.com/a/21218921/2754014about Dependency Injection. There isn't any annotation like @Autowired, @Injector @Resource. let's assume that there isn't any XML configuration for this example TwoInjectionStylesbean (except simple <context:component-scan base-package="com.example" />.
我找到了一些答案：https: //stackoverflow.com/a/21218921/2754014关于依赖注入。没有任何注释，如@Autowired,@Inject或@Resource。让我们假设这个示例TwoInjectionStylesbean没有任何 XML 配置（除了 simple <context:component-scan base-package="com.example" />.
Is it correct to inject without specify annotation?
在没有指定注释的情况下注入是否正确？
回答by Krzysztof At?asik
From Spring 4.3 annotations are not required for constructor injection.
从 Spring 4.3 开始，构造函数注入不需要注解。
public class MovieRecommender {
private CustomerPreferenceDao customerPreferenceDao;
private MovieCatalog movieCatalog;
//@Autowired - no longer necessary
public MovieRecommender(CustomerPreferenceDao customerPreferenceDao) {
this.customerPreferenceDao = customerPreferenceDao;
}
@Autowired
public setMovieCatalog(MovieCatalog movieCatalog) {
this.movieCatalog = movieCatalog;
}
}
But you still need @Autowiredfor setter injection. I checked a moment ago with Spring Boot 1.5.7(using Spring 4.3.11) and when I removed @Autowiredthen bean was not injected.
但是你仍然需要@Autowiredsetter 注入。我刚才用Spring Boot 1.5.7(using Spring 4.3.11)进行了检查，当我删除时@Autowired，没有注入 bean。
回答by Alex Saunin
Yes, example is correct (starting from Spring 4.3 release). According to the documentation (thisfor ex), if a bean has singleconstructor, @Autowiredannotation can be omitted.
是的，示例是正确的（从 Spring 4.3 版本开始）。根据文档（例如this），如果 bean 具有单个构造函数，@Autowired则可以省略注释。
But there are several nuances:
但是有几个细微差别：
1.When single constructor is present and setter is marked with @Autowiredannotation, than both constructor & setter injection will be performed one after another:
1.当单个构造函数存在并且setter被@Autowired注解标记时，构造函数和setter注入将依次执行：
@Component
public class TwoInjectionStyles {
private Foo foo;
public TwoInjectionStyles(Foo f) {
this.foo = f; //Called firstly
}
@Autowired
public void setFoo(Foo f) {
this.foo = f; //Called secondly
}
}
2.At the other hand, if there is no @Autowireat all (as in your example), than fobject will be injected once via constructor, and setter can be used in it's common way without any injections.
2.另一方面，如果根本没有@Autowire（如您的示例），则f对象将通过构造函数注入一次，并且 setter 可以在没有任何注入的情况下以常见方式使用。
