spring 局部事务

spring 支持注解式事务，作用于方法级别，我们如果想将事务放进行级别，可以使用编程式事务，如使用 TransactionTemplate。还有另外一种使用 Lambda 表达式，结合事务注解来达到行级别的事务，通过将一个方法接口传入，在一个注解事务方法中执行，就达到了行级别的事务控制。

public class Transactions {

    private static final ThreadLocal<Boolean> tl = new ThreadLocal<>();

    @Transactional(propagation = Propagation.REQUIRES_NEW, rollbackFor = Throwable.class, timeout = 15)
    public <T> T requiredNew(Supplier<T> supplier) {
        Boolean flag = tl.get();
        if (flag != null) {
            throw new RuntimeException("nested transaction is not supported!");
        }
        try {
            tl.set(true);
            return supplier.get();
        } finally {
            tl.remove();
        }
    }

    @Transactional(propagation = Propagation.REQUIRED, rollbackFor = Throwable.class, timeout = 15)
    public <T> T required(Supplier<T> supplier) {
        return supplier.get();
    }
}

@Service
public class Dmeo{
  @Autowired
  private Transactions transactions;

  public void demo(){
      transactions.required(() -> {
      //  do something
      });
  }
}