使已定义的spring bean为主要对象

Question

I have 3 beans of the same type defined in spring.xml. This is inside a jar file which I cannot edit. I want to make one of these primary in my spring-boot application using annotation. Is there a way to do it?

Answer 1

A straightforward approach is to use a bridge configuration, which will register the desired bean as a new primary bean. A simple example:

The interface:

public interface Greeter { String greet(); }

The configuration which you don't control:

@Configuration
public class Config1 {
    @Bean public Greeter british(){ return () -> "Hi"; }
    @Bean public Greeter obiWan(){ return () -> "Hello there"; }
    @Bean public Greeter american(){ return () -> "Howdy"; }
}

The bridge configuration:

@Configuration
public class Config2 {
    @Primary @Bean public Greeter primary(@Qualifier("obiWan") Greeter g) { 
        return g; 
    }
}

The client code:

@RestController
public class ControllerImpl {
    @Autowired
    Greeter greeter;

    @RequestMapping(path = "/test", method = RequestMethod.GET)
    public String test() {
        return greeter.greet();
    }
}

Result of curl http://localhost:8080/test will be

Hello there

Answer 2

您可以使用@Qualifier("___beanName__")注释选择正确的注释

Answer 3

I tried @jihor solutions but it doesn't work. I have a NullPointerException in defined configuration.

Then I find the next solution on Spring Boot

@Configuration
public class Config1 {
    @Bean
    @ConfigurationProperties(prefix = "spring.datasource.ddbb")
    public JndiPropertyHolder ddbbProperties() {
        return new JndiPropertyHolder();
    }

    @ConditionalOnProperty(name = "spring.datasource.ddbb.primary", matchIfMissing = false, havingValue = "true")
    @Bean("ddbbDataSource")
    @Primary
    public DataSource ddbbDataSourcePrimary() {
        return new JndiDataSourceLookup().getDataSource(ddbbProperties().getJndiName());
    }

    @ConditionalOnProperty(name = "spring.datasource.ddbb.primary", matchIfMissing = true, havingValue = "false")
    @Bean("ddbbDataSource")
    public DataSource ddbbDataSource() {
        return new JndiDataSourceLookup().getDataSource(ddbbProperties().getJndiName());
    }
}

And my application.properties if I need this datasource as primary, otherwise don't set the property or set false.

spring.datasource.ddbb.primary=true