聊聊langchain4j的AiServicesAutoConfig

序

本文主要研究一下langchain4j-spring-boot-starter的AiServicesAutoConfig

LangChain4jAutoConfig

dev/langchain4j/spring/LangChain4jAutoConfig.java

@AutoConfiguration
@Import({
        AiServicesAutoConfig.class,
        RagAutoConfig.class,
        AiServiceScannerProcessor.class
})
public class LangChain4jAutoConfig {
}

LangChain4jAutoConfig自动import了AiServicesAutoConfig、RagAutoConfig、AiServiceScannerProcessor

AiServiceScannerProcessor

dev/langchain4j/service/spring/AiServiceScannerProcessor.java

@Component
public class AiServiceScannerProcessor implements BeanDefinitionRegistryPostProcessor, EnvironmentAware {

    private Environment environment;

    @Override
    public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
        ClassPathAiServiceScanner scanner = new ClassPathAiServiceScanner(registry, false);
        Set<String> basePackages = getBasePackages((ConfigurableListableBeanFactory) registry);
        scanner.scan(StringUtils.toStringArray(basePackages));

        removeAiServicesWithInactiveProfiles(registry);
    }

    private Set<String> getBasePackages(ConfigurableListableBeanFactory beanFactory) {
        Set<String> basePackages = new LinkedHashSet<>();

        // AutoConfiguration
        List<String> autoConfigPackages = AutoConfigurationPackages.get(beanFactory);
        basePackages.addAll(autoConfigPackages);

        // ComponentScan
        addComponentScanPackages(beanFactory, basePackages);

        return basePackages;
    }

    private void addComponentScanPackages(ConfigurableListableBeanFactory beanFactory, Set<String> collectedBasePackages) {
        for (String beanName : beanFactory.getBeanNamesForAnnotation(ComponentScan.class)) {
            Class<?> beanClass = beanFactory.getType(beanName);
            if (beanClass != null) {
                Set<ComponentScan> componentScans = AnnotatedElementUtils.getMergedRepeatableAnnotations(beanClass, ComponentScan.class);
                for (ComponentScan componentScan : componentScans) {
                    Set<String> basePackages = new LinkedHashSet<>();
                    for (String pkg : componentScan.basePackages()) {
                        String[] tokenized = StringUtils.tokenizeToStringArray(this.environment.resolvePlaceholders(pkg),
                                ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS);
                        Collections.addAll(basePackages, tokenized);
                    }
                    for (Class<?> clazz : componentScan.basePackageClasses()) {
                        basePackages.add(ClassUtils.getPackageName(clazz));
                    }
                    if (basePackages.isEmpty()) {
                        basePackages.add(ClassUtils.getPackageName(beanClass));
                    }
                    collectedBasePackages.addAll(basePackages);
                }
            }
        }
    }

    private void removeAiServicesWithInactiveProfiles(BeanDefinitionRegistry registry) {
        Arrays.stream(registry.getBeanDefinitionNames())
                .filter(beanName -> {
                    try {
                        BeanDefinition beanDefinition = registry.getBeanDefinition(beanName);
                        if (beanDefinition.getBeanClassName() != null) {
                            Class<?> beanClass = Class.forName(beanDefinition.getBeanClassName());
                            if (beanClass.isAnnotationPresent(AiService.class)
                                    && beanClass.isAnnotationPresent(Profile.class)) {
                                Profile pr