FactoryBeans和Spring 3.0中基于注释的配置 [英] FactoryBeans and the annotation-based configuration in Spring 3.0

问题描述

Spring提供了 FactoryBean 接口，允许对bean进行非平凡的初始化。该框架提供了工厂bean的许多实现，并且 - 当使用Spring的XML配置时 - 工厂bean很容易使用。

Spring provides the FactoryBean interface to allow non-trivial initialisation of beans. The framework provides many implementations of factory beans and -- when using Spring's XML config -- factory beans are easy to use.

然而，在Spring 3.0中，我不能找到一种令人满意的工厂bean使用基于注释的配置（néeJavaConfig）的方法。

However, in Spring 3.0, I can't find a satisfactory way of using factory beans with the annotation-based configuration (née JavaConfig).

显然，我可以手动实例化工厂bean并自己设置所有必需的属性，如下所示：

Obviously, I could manually instantiate the factory bean and set any required properties myself, like so:

@Configuration
public class AppConfig {

...

    @Bean
    public SqlSessionFactory sqlSessionFactory() throws Exception {
        SqlSessionFactoryBean factory = new SqlSessionFactoryBean();
        factory.setDataSource(dataSource());
        factory.setAnotherProperty(anotherProperty());

        return factory.getObject();
    }

但是，如果 FactoryBean 实现了任何特定于Spring的回调接口，例如 InitializingBean ， ApplicationContextAware ，例如，BeanClassLoaderAware 或 @PostConstruct 。我还需要检查FactoryBean，找出它实现的回调接口，然后通过调用 setApplicationContext ， afterPropertiesSet（）等。

However, this would fail if the FactoryBean implemented any Spring-specific callback interfaces, like InitializingBean, ApplicationContextAware, BeanClassLoaderAware, or @PostConstruct for example. I also need to inspect the FactoryBean, find out what callback interfaces it implements, then implement this functionality myself by calling setApplicationContext, afterPropertiesSet() etc.

这对我来说感觉很尴尬和反过来：应用程序开发人员不应该实现IOC容器的回调。

This feels awkward and back-to-front to me: application-developers should not have to implement the callbacks of the IOC container.

有没有人知道使用Spring Annotation配置的FactoryBeans更好的解决方案？

Does anyone know of a better solution to using FactoryBeans from Spring Annotation configs?

推荐答案

据我所知你的问题是你想要的结果 sqlSessionFactory（）是一个 SqlSessionFactory （用于其他方法），但您必须从 @Bean -annotated方法返回 SqlSessionFactoryBean 为了触发Spring回调。

As far as I understand your problem is what you want a result of sqlSessionFactory() to be a SqlSessionFactory (for use in other methods), but you have to return SqlSessionFactoryBean from a @Bean-annotated method in order to trigger Spring callbacks.

可以通过以下解决方法解决：

It can be solved with the following workaround:

@Configuration 
public class AppConfig { 
    @Bean(name = "sqlSessionFactory")
    public SqlSessionFactoryBean sqlSessionFactoryBean() { ... }

    // FactoryBean is hidden behind this method
    public SqlSessionFactory sqlSessionFactory() {
        try {
            return sqlSessionFactoryBean().getObject();
        } catch (Exception ex) {
            throw new RuntimeException(ex);
        }
    }

    @Bean
    public AnotherBean anotherBean() {
        return new AnotherBean(sqlSessionFactory());
    }
}

重点是调用 @Bean -annotated方法被一个方面拦截，该方面执行返回的bean的初始化（在你的情况下为 FactoryBean ），以便调用 sqlSessionFactoryBean（） in sqlSessionFactory（）返回完全初始化的 FactoryBean 。

The point is that calls to @Bean-annotated methods are intercepted by an aspect which performs initialization of the beans being returned (FactoryBean in your case), so that call to sqlSessionFactoryBean() in sqlSessionFactory() returns a fully initialized FactoryBean.

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