我有一些现有的传统的辅助类无豆注释和不xml配置。我想创建一个相同的类豆子不经修改(不添加注释),并没有任何XML额外的配置。可能吗?
是的,这是可能的,非常简单。您需要创建自己的类,并与@Configuration
注释,然后创建@Bean
返回助手类注释的方法。类似的东西:
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class MyConfigClass {
@Bean
public HelperClass helperClassName() {
return new HelperClass();
}
}
您可以使用@Bean
从另一个调用一个方法@Configuration
,并得到一个完全初始化实例,如下所示:
public class Foo {
@Value("Hello, world!")
public String value;
}
@Configuration
public class Config {
@Bean
public Foo createFoo() {
Foo foo = new Foo();
System.out.println(foo.value); // Prints null - foo not initialized yet
return foo;
}
@Bean
public Bar createBar() {
Foo foo = createFoo();
System.out.println(foo.value); // Prints Hello, world! - foo have been initialized by the interceptor
return new Bar(foo);
}
}
另一种选择是使用BeanDefinitionRegistryPostProcessor
和手动注册类。
@Configuration
@ConditionalOnClass({
LegacyBeansAutoConfiguration.Legacy1.class,
LegacyBeansAutoConfiguration.Legacy2.class,
LegacyBeansAutoConfiguration.Legacy3.class
})
@EnableAutoConfiguration(exclude = LiquibaseAutoConfiguration.class)
public class LegacyBeansAutoConfiguration implements
BeanDefinitionRegistryPostProcessor {
@Override
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry beanDefinitionRegistry) throws BeansException {
RootBeanDefinition beanDefinition1 = new RootBeanDefinition(Legacy1.class, Legacy1::new);
beanDefinitionRegistry.registerBeanDefinition(Legacy1.class.getName(), beanDefinition1);
RootBeanDefinition beanDefinition2 = new RootBeanDefinition(Legacy2.class, Legacy2::new);
beanDefinitionRegistry.registerBeanDefinition(Legacy2.class.getName(), beanDefinition2);
RootBeanDefinition beanDefinition3 = new RootBeanDefinition(Legacy3.class, Legacy3::new);
beanDefinitionRegistry.registerBeanDefinition(Legacy3.class.getName(), beanDefinition3);
}
@Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory configurableListableBeanFactory) throws BeansException {
// n00p
}
class Legacy1 {
}
class Legacy2 {
}
class Legacy3 {
}
}
下面有一个测试,确认咖啡豆注册:
@RunWith(SpringRunner.class)
@SpringBootTest
public class LegacyBeansAutoConfigurationTest {
@Autowired
ApplicationContext context;
@Test
public void contextLoads() {
Assertions.assertThat(context.getBeanNamesForType(LegacyBeansAutoConfiguration.Legacy1.class)).isNotNull();
Assertions.assertThat(context.getBeanNamesForType(LegacyBeansAutoConfiguration.Legacy2.class)).isNotNull();
Assertions.assertThat(context.getBeanNamesForType(LegacyBeansAutoConfiguration.Legacy3.class)).isNotNull();
}
}