解读@Transactional失效的几种情况

//@Transactional注解在private方法上会失效
@Transactional
private void deleteUser() throws MyException{
    userMapper.deleteUserA();
    int i = 1/0;
    userMapper.deleteUserB();
}

    /**
     * Same signature as {@link #getTransactionAttribute}, but doesn't cache the result.
     * {@link #getTransactionAttribute} is effectively a caching decorator for this method.
     * <p>As of 4.1.8, this method can be overridden.
     * @since 4.1.8
     * @see #getTransactionAttribute
     */
    protected TransactionAttribute computeTransactionAttribute(Method method, Class<?> targetClass) {
        // Don't allow no-public methods as required.
        if (allowPublicMethodsOnly() && !Modifier.isPublic(method.getModifiers())) {
            return null;
        }
    //...
  }

@Transactional
public void deleteUser() {
    userMapper.deleteUserA();
    try {
        int i = 1 / 0;
        userMapper.deleteUserB();
    } catch (Exception e) {
        e.printStackTrace();
    }
}

@Transactional
public void deleteUser() throws MyException{
    userMapper.deleteUserA();
    try {
        int i = 1 / 0;
        userMapper.deleteUserB();
    } catch (Exception e) {
        throw new MyException();
    }
}

@Transactional(rollbackFor = Exception.class)

public void deleteUser() throws MyException{
    deleteUser2(); // 事物失效
}

@Transactional
public void deleteUser2() throws MyException{
    userMapper.deleteUserA();
    int i = 1 / 0;
    userMapper.deleteUserB();
}

    @Primary
    @Bean(name = "db1")
    public DataSource getDataSource() {
        return createDataSource();
    }
    @Bean(name = "db1TransactionManager")
    public PlatformTransactionManager txManager(@Qualifier("db1") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }

   @Bean(name = "db2")
   public DataSource getDataSource() {
       return buildDataSource();
   }
   @Bean(name = "db2TransactionManager")
   public PlatformTransactionManager txManager(@Qualifier("db2") DataSource dataSource) {
       return new DataSourceTransactionManager(dataSource);
   }

   @Override
   @Transactional(value = "db1TransactionManager",rollbackFor = Exception.class)
   public int updateOrInsert(BaseRequest<BankTemplateDto> param) {
      ...
   }

@Transactional
public void deleteUser() throws MyException{
    userMapper.deleteUserA();
    try {
        //休眠1秒，保证deleteUserA先执行
        Thread.sleep(1000);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
    new Thread(() -> {
        int i = 1/0;
        userMapper.deleteUserB();
    }).start();    
}