1. 可在catch中抛出运行时异常throw new RuntimeException(e)(注:默认回滚的是RuntimeException,如果你想触发其他异常的回滚,需要在注解上配置一下)
  2. 手动回滚TransactionAspectSupport.currentTransactionStatus().setRollbackOnly(),使得事务生效,出现异常回滚。
@Transactional(rollbackFor = Exception.class)
public AjaxResult update(@RequestBody RestaurantVo entity) {
    AjaxResult ajaxResult = new AjaxResult();
    try {
        service.save(entity);
        return ajaxResult.success("success");
    } catch (Exception e) {
        //throw new RuntimeException(e);
        TransactionAspectSupport.currentTransactionStatus().setRollbackOnly();
        return ajaxResult.fail("500", e.getMessage());
    }
}