@Import({ DataSourcePoolMetadataProvidersConfiguration.class, DataSourceInitializationConfiguration.class })
public class DataSourceAutoConfiguration {
// 引入了DataSourceInitializationConfiguration類
@Configuration(proxyBeanMethods = false)
@Import({ DataSourceInitializerInvoker.class, DataSourceInitializationConfiguration.Registrar.class })
class DataSourceInitializationConfiguration {
/**
* {@link ImportBeanDefinitionRegistrar} to register the
* {@link DataSourceInitializerPostProcessor} without causing early bean instantiation
* issues.
*/
static class Registrar implements ImportBeanDefinitionRegistrar {
private static final String BEAN_NAME = "dataSourceInitializerPostProcessor";
@Override
public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata,
BeanDefinitionRegistry registry) {
// 這里判斷是否有dataSourceInitializerPostProcessor這個bean，如果沒有則會創建
if (!registry.containsBeanDefinition(BEAN_NAME)) {
GenericBeanDefinition beanDefinition = new GenericBeanDefinition();
beanDefinition.setBeanClass(DataSourceInitializerPostProcessor.class);
beanDefinition.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
// We don't need this one to be post processed otherwise it can cause a
// cascade of bean instantiation that we would rather avoid.
beanDefinition.setSynthetic(true);
registry.registerBeanDefinition(BEAN_NAME, beanDefinition);
}
}
}
}
class DataSourceInitializerPostProcessor implements BeanPostProcessor, Ordered {
@Override
public int getOrder() {
return Ordered.HIGHEST_PRECEDENCE + 1;
}
@Autowired
private BeanFactory beanFactory;
@Override
public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
return bean;
}
@Override
public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
if (bean instanceof DataSource) {
// force initialization of this bean as soon as we see a DataSource
// 如果bean是DataSource類型，就會獲取DataSourceInitializerInvoker這個類
this.beanFactory.getBean(DataSourceInitializerInvoker.class);
}
return bean;
}
}
@Override
public void afterPropertiesSet() {
DataSourceInitializer initializer = getDataSourceInitializer();
if (initializer != null) {
// 這里有一個判斷是否創建Schema
boolean schemaCreated = this.dataSourceInitializer.createSchema();
if (schemaCreated) {
initialize(initializer);
}
}
}
boolean createSchema() {
List<Resource> scripts = getScripts("spring.datasource.schema", this.properties.getSchema(), "schema");
if (!scripts.isEmpty()) {
if (!isEnabled()) {
logger.debug("Initialization disabled (not running DDL scripts)");
return false;
}
String username = this.properties.getSchemaUsername();
String password = this.properties.getSchemaPassword();
runScripts(scripts, username, password);
}
return !scripts.isEmpty();
}
// 如果是NEVER或者是EMBEDDED就不會創建，所以我們要在配置文件中增加initialization-mode: always屬性
private boolean isEnabled() {
DataSourceInitializationMode mode = this.properties.getInitializationMode();
if (mode == DataSourceInitializationMode.NEVER) {
return false;
}
if (mode == DataSourceInitializationMode.EMBEDDED && !isEmbedded()) {
return false;
}
return true;
}