SpringBoot原始碼之事物篇（一）事物是在哪裡開啟的呢？
最近正在學習使用JPA，JPA是預設開啟事物管理的，在哪裡開啟的呢？？？突然覺得對spring處理事物的原理一竊不通，才有了這次的原始碼閱讀之行，有不正確的地方歡迎大家指正。
先簡略過一下springboot的執行原理
public void processConfigBeanDefinitions(BeanDefinitionRegistry registry)方法
上圖中的imports包括如下內容：
[org.springframework.boot.autoconfigure.context.MessageSourceAutoConfiguration,
org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration,
org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration,
org.springframework.boot.autoconfigure.websocket.WebSocketAutoConfiguration,
org.springframework.boot.autoconfigure.web.EmbeddedServletContainerAutoConfiguration,
org.springframework.boot.autoconfigure.web.DispatcherServletAutoConfiguration,
org.springframework.boot.autoconfigure.validation.ValidationAutoConfiguration,
org.springframework.boot.autoconfigure.web.ErrorMvcAutoConfiguration,
org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration,
org.springframework.boot.autoconfigure.jmx.JmxAutoConfiguration,
org.springframework.boot.autoconfigure.admin.SpringApplicationAdminJmxAutoConfiguration,
org.springframework.boot.autoconfigure.aop.AopAutoConfiguration,
org.springframework.boot.autoconfigure.jdbc.JndiDataSourceAutoConfiguration,
org.springframework.boot.autoconfigure.transaction.jta.JtaAutoConfiguration,
org.springframework.boot.autoconfigure.jdbc.XADataSourceAutoConfiguration,
org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration,
org.springframework.boot.autoconfigure.cache.CacheAutoConfiguration,
org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration,
org.springframework.boot.autoconfigure.context.ConfigurationPropertiesAutoConfiguration,
org.springframework.boot.autoconfigure.dao.PersistenceExceptionTranslationAutoConfiguration,
org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration,
org.springframework.boot.autoconfigure.web.HttpMessageConvertersAutoConfiguration,
org.springframework.boot.autoconfigure.data.web.SpringDataWebAutoConfiguration,
org.springframework.boot.autoconfigure.info.ProjectInfoAutoConfiguration,
org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration,
org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration,
org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration,
org.springframework.boot.autoconfigure.mail.MailSenderValidatorAutoConfiguration,
org.springframework.boot.autoconfigure.web.HttpEncodingAutoConfiguration,
org.springframework.boot.autoconfigure.web.MultipartAutoConfiguration,
org.springframework.boot.autoconfigure.web.ServerPropertiesAutoConfiguration,
org.springframework.boot.autoconfigure.web.WebClientAutoConfiguration]
看到一個事物相關的自動配置， org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration，原始碼中有這個註解 @EnableTransactionManagement，事物開啟！！！！：
@Configuration
@ConditionalOnClass(PlatformTransactionManager.class)
@AutoConfigureAfter({ JtaAutoConfiguration.class, HibernateJpaAutoConfiguration.class,
DataSourceTransactionManagerAutoConfiguration.class,
Neo4jDataAutoConfiguration.class })
@EnableConfigurationProperties(TransactionProperties.class)
public class TransactionAutoConfiguration {
@Bean
@ConditionalOnMissingBean
public TransactionManagerCustomizers platformTransactionManagerCustomizers(
ObjectProvider<List<PlatformTransactionManagerCustomizer<?>>> customizers) {
return new TransactionManagerCustomizers(customizers.getIfAvailable());
}
@Configuration
@ConditionalOnSingleCandidate(PlatformTransactionManager.class)
public static class TransactionTemplateConfiguration {
private final PlatformTransactionManager transactionManager;
public TransactionTemplateConfiguration(
PlatformTransactionManager transactionManager) {
this.transactionManager = transactionManager;
}
@Bean
@ConditionalOnMissingBean
public TransactionTemplate transactionTemplate() {
return new TransactionTemplate(this.transactionManager);
}
}
@Configuration
@ConditionalOnBean(PlatformTransactionManager.class)
@ConditionalOnMissingBean(AbstractTransactionManagementConfiguration.class)
public static class EnableTransactionManagementConfiguration {
@Configuration
@EnableTransactionManagement(proxyTargetClass = false)
@ConditionalOnProperty(prefix = "spring.aop", name = "proxy-target-class", havingValue = "false", matchIfMissing = false)
public static class JdkDynamicAutoProxyConfiguration {
}
@Configuration
@EnableTransactionManagement(proxyTargetClass = true)
@ConditionalOnProperty(prefix = "spring.aop", name = "proxy-target-class", havingValue = "true", matchIfMissing = true)
public static class CglibAutoProxyConfiguration {
}
}
}