如何在运行时实例化Spring受管Bean？ [英] How to instantiate spring managed beans at runtime?
问题描述
public class Container {
private List< RuntimeBean> runtimeBeans = new ArrayList< RuntimeBean>（）;
public void load（）{
//根据外部数据/环境重复几次
RuntimeBean beanRuntime = createRuntimeBean（）;
runtimeBeans.add（beanRuntime）;
}
public RuntimeBean createRuntimeBean（）{
//应该创建bean，内部可以有一些
//弹簧注释，换句话说，
/ /应该由spring
}
}
基本上，在加载容器请求一些外部系统向他提供有关每个RuntimeBean的数量和配置的信息，然后根据给定的规格创建bean。
问题是：通常当我们在春天
ApplicationContext context = new AnnotationConfigApplicationContext（ApplicationConfiguration.class）;
容器容器=（容器）context.getBean（container）;
我们的对象已完全配置，并注入了所有依赖项。但是在我的情况下，我必须实例化一些在执行load（）方法后也需要依赖注入的对象。
我该如何实现？
我正在使用基于java的配置。我已经尝试为RuntimeBeans制作一个工厂：
public class BeanRuntimeFactory {
@Bean
public RuntimeBean createRuntimeBean（）{
return new RuntimeBean（）;
}
}
expecting @Bean在所谓的lite模式。 http：//docs.spring 。/ / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / /
这是一个类似问题的帖子：如何获得由FactoryBean spring创建的bean管理？
还有一个 http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/ bean / factory / annotation / Configurable.html ，但在我的情况下看起来像是一把锤子。
我也尝试过ApplicationContext.getBean（runtimeBean，args ）其中runtimeBean有一个Prototype范围，但getBean是一个很糟糕的解决方案。
Upd1。
为了更具体一些我试图重构这个类：
https://github.com/apache/lucene-solr/blob/trunk/solr/core/s rc / java / org / apache / solr / core / CoreContainer.java
@see #load（）方法并找到return create（cd，false）;
Upd2。
我在spring文档中发现了非常有趣的东西叫做lookup method injection：
http://docs.spring.io/spring/ docs / current / spring-framework-reference / html / beans.html＃beans-factory-lookup-method-injection
还有一个有趣的jira票Phil Webb说的 https://jira.spring.io/browse/SPR-5192 https://jira.spring.io/browse/SPR-5192?focusedCommentId=86051&page=com.atlassian.jira.plugin.system.issuetabp anels：comment-tabpanel＃comment-86051 应该在这里使用javax.inject.Provider（它提醒我Guice）。
Upd4。
所有这些查找方法的问题是它们不支持传递任何参数。我还需要传递参数使用applicationContext.getBean（runtimeBean，arg1，arg2）。在 https://jira.spring.io/browse/SPR- 7431
Upd5。 Google Guice具有称为AssistedInject的整洁功能。 https://github.com/google/guice/wiki/AssistedInject
看起来我发现了一个解决方案。因为我使用基于java的配置，它比你想像的要简单得多。 xml中的替代方法是lookup-method，但是只能从spring version 4.1.X，因为它支持传递方法的参数。
这是一个完整的工作示例： / p>
public class Container {
private List&RuntimeBean> runtimeBeans = new ArrayList< RuntimeBean>（）;
private RuntimeBeanFactory runtimeBeanFactory;
public void load（）{
//根据外部数据/环境重复几次
runtimeBeans.add（createRuntimeBean（Some external info1））;
runtimeBeans.add（createRuntimeBean（Some external info2））;
}
public RuntimeBean createRuntimeBean（String info）{
//应该创建内部可以有一些
//弹簧注释的bean，换句话说就是
//应该由spring
返回runtimeBeanFactory.createRuntimeBean（info）
}
public void setRuntimeBeanFactory（RuntimeBeanFactory runtimeBeanFactory）{
this.runtimeBeanFactory = runtimeBeanFactory
}
}
public interface RuntimeBeanFactory {
RuntimeBean createRuntimeBean（String info）;
}
//最后
@Configuration
public class ApplicationConfiguration {
@Bean
容器容器（）{
容器容器=新容器（beanToInject（））;
container.setBeanRuntimeFactory（runtimeBeanFactory（））;
返回容器;
}
//看看它在JAVA配置中如何简单
@Bean
public BeanRuntimeFactory runtimeBeanFactory（）{
return new BeanRuntimeFactory（）{
public RuntimeBean createRuntimeBean（String beanName）{
return runtimeBean（beanName）;
}
};
}
@Bean
@Scope（ConfigurableBeanFactory.SCOPE_PROTOTYPE）
RuntimeBean runtimeBean（String beanName）{
返回新的RuntimeBean（beanName）;
}
}
class RuntimeBean {
@Autowired
容器容器;
}
就是这样。
谢谢大家。
I stuck with a simple refactoring from plain java to spring. Application has a "Container" object which instantiates its parts at runtime. Let me explain with the code:
public class Container {
private List<RuntimeBean> runtimeBeans = new ArrayList<RuntimeBean>();
public void load() {
// repeated several times depending on external data/environment
RuntimeBean beanRuntime = createRuntimeBean();
runtimeBeans.add(beanRuntime);
}
public RuntimeBean createRuntimeBean() {
// should create bean which internally can have some
// spring annotations or in other words
// should be managed by spring
}
}
Basically, during load container asks some external system to provide him information about number and configuration of each RuntimeBean and then it create beans according to given spec.
The problem is: usually when we do in spring
ApplicationContext context = new AnnotationConfigApplicationContext(ApplicationConfiguration.class);
Container container = (Container) context.getBean("container");
our object is fully configured and have all dependencies injected. But in my case I have to instantiate some objects which also needs dependency injection after I execute load() method. How can I achieve that?
I am using java-based config. I already tried making a factory for RuntimeBeans:
public class BeanRuntimeFactory {
@Bean
public RuntimeBean createRuntimeBean() {
return new RuntimeBean();
}
}
expecting @Bean to work in so called 'lite' mode. http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/context/annotation/Bean.html Unfortunately, I found no difference with simply doing new RuntimeBean(); Here is a post with a similar issue: How to get beans created by FactoryBean spring managed?
There is also http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/beans/factory/annotation/Configurable.html but it looks like a hammer in my case.
I also tried ApplicationContext.getBean("runtimeBean", args) where runtimeBean has a "Prototype" scope, but getBean is an awful solution.
Upd1. To be more concrete I am trying to refactor this class: https://github.com/apache/lucene-solr/blob/trunk/solr/core/src/java/org/apache/solr/core/CoreContainer.java @see #load() method and find "return create(cd, false);"
Upd2. I found quite interesting thing called "lookup method injection" in spring documentation: http://docs.spring.io/spring/docs/current/spring-framework-reference/html/beans.html#beans-factory-lookup-method-injection
And also an interesting jira ticket https://jira.spring.io/browse/SPR-5192 where Phil Webb says https://jira.spring.io/browse/SPR-5192?focusedCommentId=86051&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-86051 that javax.inject.Provider should be used here (it reminds me Guice).
Upd3. There is also http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/beans/factory/config/ServiceLocatorFactoryBean.html
Upd4. The issue with all these 'lookup' methods is they don't support passing any arguments.. I also need to pass arguments as I would do with applicationContext.getBean("runtimeBean", arg1, arg2). Looks like it was fixed at some point with https://jira.spring.io/browse/SPR-7431
Upd5. Google Guice have a neat feature for it called AssistedInject. https://github.com/google/guice/wiki/AssistedInject
Looks like I found a solution. As I am using java based configuration it is even simpler than you can imagine. Alternative way in xml would be lookup-method, however only from spring version 4.1.X as it supports passing arguments to the method.
Here is a complete working example:
public class Container {
private List<RuntimeBean> runtimeBeans = new ArrayList<RuntimeBean>();
private RuntimeBeanFactory runtimeBeanFactory;
public void load() {
// repeated several times depending on external data/environment
runtimeBeans.add(createRuntimeBean("Some external info1"));
runtimeBeans.add(createRuntimeBean("Some external info2"));
}
public RuntimeBean createRuntimeBean(String info) {
// should create bean which internally can have some
// spring annotations or in other words
// should be managed by spring
return runtimeBeanFactory.createRuntimeBean(info)
}
public void setRuntimeBeanFactory(RuntimeBeanFactory runtimeBeanFactory) {
this.runtimeBeanFactory = runtimeBeanFactory
}
}
public interface RuntimeBeanFactory {
RuntimeBean createRuntimeBean(String info);
}
//and finally
@Configuration
public class ApplicationConfiguration {
@Bean
Container container() {
Container container = new Container(beanToInject());
container.setBeanRuntimeFactory(runtimeBeanFactory());
return container;
}
// LOOK HOW IT IS SIMPLE IN THE JAVA CONFIGURATION
@Bean
public BeanRuntimeFactory runtimeBeanFactory() {
return new BeanRuntimeFactory() {
public RuntimeBean createRuntimeBean(String beanName) {
return runtimeBean(beanName);
}
};
}
@Bean
@Scope(ConfigurableBeanFactory.SCOPE_PROTOTYPE)
RuntimeBean runtimeBean(String beanName) {
return new RuntimeBean(beanName);
}
}
class RuntimeBean {
@Autowired
Container container;
}
That's it.
Thanks everyone.
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