java Spring Boot @Autowired 在运行时创建实例
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Spring Boot @Autowired creating instances on a runtime
提问by Supo
As most of Spring Boot new users I have a problem with @Autowired :D
作为大多数 Spring Boot 新用户，我对 @Autowired 有问题：D
I've readed a big amount of topics about this annotation here But still can't find proper solution for my problem.
我在这里阅读了大量有关此注释的主题，但仍然无法为我的问题找到合适的解决方案。
Let's suppose that we have this Spring Boot hierarchy:
假设我们有这个 Spring Boot 层次结构：
@SpringBootApplication
public class DemoApplication {
public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
}
Class, that we wanna instantiate every time it's called:
类，我们想在每次调用时实例化：
@Service
public class TestWire {
public TestWire() {
System.out.println("INSTANCE CREATED: " + this);
}
}
Out get controller, that creates new SomeRepo object every request:
取出控制器，它会在每个请求中创建新的 SomeRepo 对象：
@RestController
public class CreatingRepo {
@RequestMapping("/")
public void postMessage() {
SomeRepo repo = new SomeRepo();
}
}
Finally, class, that uses @Autowired to create TestWire instances:
最后，使用@Autowired 创建 TestWire 实例的类：
public class SomeRepo {
@Autowired
private TestWire testWire;
public SomeRepo() {
System.out.println(testWire.toString());
}
}
Let's assume, that we make GET request to "/" several times.
假设我们多次向“/”发出 GET 请求。
So, as a result, TestWire class will isntantiate only when project builds and neither @Scope(value = "prototype"), nor proxyMode = ScopedProxyMode.TARGET_CLASSwont help.
因此，因此，TestWire 类仅在项目构建时才会生效，@Scope(value = "prototype")和proxyMode = ScopedProxyMode.TARGET_CLASS 都无济于事。
Any ideas how to create new instances at runtime? I mean, how can we do it in "Spring way"? Without factories and other things, only Spring DI through annotation and configuration.
任何想法如何在运行时创建新实例？我的意思是，我们如何以“Spring 方式”做到这一点？没有工厂等东西，只有通过注解和配置的Spring DI。
Upd. A piece of stack trace, where instance created:
更新。一段堆栈跟踪，其中创建了实例：
2015-11-16 20:30:41.032 INFO 17696 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
INSTANCE CREATED: com.example.TestWire@56c698e3
2015-11-16 20:30:41.491 INFO 17696 --- [ main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@12f41634: startup date [Mon Nov 16 20:30:37 MSK 2015]; root of context hierarchy
2015-11-16 20:30:41.566 INFO 17696 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/]}" onto public void com.example.CreatingRepo.postMessage()
回答by d0x
If I understood you correct you need to annotate the SomeRepolike this:
如果我理解你是正确的，你需要SomeRepo像这样注释：
@Service
@Scope(value = "prototype")
public class SomeRepo {
// ...
}
Option A:
选项A：
Instead of instantiating the class with new SomeRepo();you ask the BeanFactory.getBean(...)for it.
而不是用new SomeRepo();你请求BeanFactory.getBean(...)它来实例化这个类。
@RestController
public class CreatingRepo {
@Autowired
BeanFactory beanFactory;
@RequestMapping("/")
public void postMessage() {
// instead of new SomeBean we get it from the BeanFactory
SomeRepo repo = beanFactory.getBean(SomeRepo.class);
}
}
Option B:
选项 B：
You should also be able to get the Bean like this (over paramters without the beanFactory):
您还应该能够像这样获得 Bean（通过没有 的参数beanFactory）：
@RestController
public class CreatingRepo {
@RequestMapping("/")
public void postMessage(SomeRepo repo) {
// instead of the BeanFactory and using new SomeRepo you can get it like this.
}
}
