导入其他没有它的bean的Spring Boot应用程序

Question

I want to use some classes that exist inside another spring boot application. How can I import them whitout loading all it's beans in my application.

Answer 1

The @ComponentScan annotation is responsible for automatically loading any classes marked with @Component or its derived annotations. This annotation has various options to filter which beans are loaded.

If the parent package of the imported application is different from that of your main application, you can simply set the basePackages option to a specific parent package.

For example, say that your main application has the package com.example.main and the imported application has com.example.imported , you can put in:

@ComponentScan(basePackages = {"com.example.main"})

This will import only beans defined under the main application package.

If this is not enough, you can also use the excludeFilters option on the same annotation.

@ComponentScan(excludeFilters={
  @ComponentScan.Filter(type=FilterType.ASSIGNABLE_TYPE, value=Imported.class)
})

You can also combine both options for more specific filtering.

Answer 2

@metacubed answer is probably sufficient. But another very simple approach would be to use @ComponentScan(basePackageClasses = {BeansToExport.class, MoreBeansToExport.class, ...}) - Example:

@Configuration
public class BeansToExport {

   @Bean
   public ServiceClass serviceClassBean(){
      return new ServiceClass();
   }

   @Bean
   public RespositoryClass repositoryClassBean(){
      return new RepositoryClass();
   }

}

I would call this an inclusive strategy, whereas @metacube's example would be an exclusive strategy. Both have their uses.