该类是每层事务的抽象,并且是一个链表结构,一个节点表示一层事务,这链表(这多层事务)对应着同一个TransactionInterceptor和同一个PlatformTransactionManager
由于该类是一个protected修饰的TransactionAspectSupport的内部类,所以如果自己想查看执行事务时候,当前事务的属性,应该通过反射机制调用currentTransactionInfo方法才可以,本文后续会有调试代码
该类是TransactionAspectSupport类的内部类,有下面几个属性
@Nullable
private final PlatformTransactionManager transactionManager;
@Nullable
private final TransactionAttribute transactionAttribute;
private final String joinpointIdentification;
@Nullable
private TransactionStatus transactionStatus;
@Nullable
private TransactionInfo oldTransactionInfo;
其中transactionManager,transactionAttribute,transactionStatus,都已经介绍过,本文着重阐述joinpointIdentification和oldTransactionInfo
一:joinpointIdentification
要执行事务的方法的全限定名,字符串形式
二:oldTransactionInfo
表示在哪个事务中开启的事务,比如A事务里有事务B,那么此时就有两个TransactionInfo,后一个TransactionInfo(B)包含着一个前一个TransactionInfo(A)的引用,这个指针用oldTransactionInfo属性来表示
下面是证明oldTransactionInfo过程,不爱看的不看
创建第一个事务类Create1
@Component
public class Creater1 {
@Autowired
JdbcTemplate jdbcTemplate;
@Autowired
Creater2 creater2;
@Transactional(rollbackFor = Exception.class)
public void create() throws Exception {
jdbcTemplate.update("insert into t1(value) values ('爱1次马银霜')");
Class<TransactionAspectSupport> clazz = TransactionAspectSupport.class;
Method m = clazz.getDeclaredMethod("currentTransactionInfo");
m.setAccessible(true);
Object o = m.invoke(clazz);
System.out.println(o);// 将断点打到这里观察oldTransactionInfo属性
creater2.create();
}
}
创建第二个事务类Create2,用来在Create1中嵌套
@Component
public class Creater2 {
@Autowired
JdbcTemplate jdbcTemplate;
@Transactional(rollbackFor = Exception.class, propagation = Propagation.REQUIRED)
public void create() throws Exception {
jdbcTemplate.update("insert into t1(value) values ('爱2次马银霜')");
Class<TransactionAspectSupport> clazz = TransactionAspectSupport.class;
Method m = clazz.getDeclaredMethod("currentTransactionInfo");
m.setAccessible(true);
Object o = m.invoke(clazz);// 将断点打到这里观察oldTransactionInfo属性
System.out.println(o);
}
}
创建Main方法,并且运行,查看断点处,可发现oldTransactionInfo的值,正好一个事务对应一个info
@Configuration
@EnableTransactionManagement
public class TestMain {
@Bean
public DataSource dataSource() {
HikariDataSource ds = new HikariDataSource();
ds.setJdbcUrl("jdbc:mysql://localhost:3306/swttest?serverTimezone=UTC&&useSSL=false");
ds.setUsername("root");
ds.setPassword("123456");
return ds;
}
@Bean
public JdbcTemplate jdbcTemplate() {
JdbcTemplate jdbc = new JdbcTemplate();
jdbc.setDataSource(dataSource());
return jdbc;
}
@Bean
public PlatformTransactionManager platformTransactionManager() {
DataSourceTransactionManager manager = new DataSourceTransactionManager(dataSource());
return manager;
}
public static void main(String[] args) throws Throwable {
// 依赖容器的话必须要开启@EnableTransactionManagement注解,表示告诉spring我要使用事务
AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(
"基础包名");
Creater1 tt = ctx.getBean(Creater1.class);
tt.create();
}
}