Spring中是否有ServiceLoader的模擬以及如何使用它？

Question

我想知道是否有類似於標準SDK API的ServiceLoader類的Spring模擬器。如果有這樣的課程，它是如何使用的？

請指教！

Answer 1

假設SpringFactoriesLoader是給你的。從它的JavaDocs：

* General purpose factory loading mechanism for internal use within the framework. 
* 
* <p>The {@code SpringFactoriesLoader} loads and instantiates factories of a given type 
* from "META-INF/spring.factories" files. The file should be in {@link Properties} format, 
* where the key is the fully qualified interface or abstract class name, and the value 
* is a comma-separated list of implementation class names. For instance: 
* 
* <pre class="code">example.MyService=example.MyServiceImpl1,example.MyServiceImpl2</pre> 
* 
* where {@code MyService} is the name of the interface, and {@code MyServiceImpl1} and 
* {@code MyServiceImpl2} are the two implementations. 

從我們項目的一個樣本：

META-INF/spring.factories：

org.springframework.integration.config.IntegrationConfigurationInitializer=\ 
org.springframework.integration.config.GlobalChannelInterceptorInitializer,\ 
org.springframework.integration.config.IntegrationConverterInitializer 

實施：

public class IntegrationConfigurationBeanFactoryPostProcessor implements BeanFactoryPostProcessor { 

    @Override 
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException { 
     Set<String> initializerNames = new HashSet<String>(
       SpringFactoriesLoader.loadFactoryNames(IntegrationConfigurationInitializer.class, beanFactory.getBeanClassLoader())); 

     for (String initializerName : initializerNames) { 
      try { 
       Class<?> instanceClass = ClassUtils.forName(initializerName, beanFactory.getBeanClassLoader()); 
       Assert.isAssignable(IntegrationConfigurationInitializer.class, instanceClass); 
       IntegrationConfigurationInitializer instance = (IntegrationConfigurationInitializer) instanceClass.newInstance(); 
       instance.initialize(beanFactory); 
      } 
      catch (Exception e) { 
       throw new IllegalArgumentException("Cannot instantiate 'IntegrationConfigurationInitializer': " + initializerName, e); 
      } 
     } 
    } 

}