How can distributed transactions be implemented in Java?

There are multiple ways to implement distributed transactions in Java, below are some common implementation methods:

1. Two-Phase Commit (2PC): 2PC is a classic distributed transaction protocol that involves two roles – the coordinator and participant. The coordinator is responsible for coordinating transactions between all participants, and ultimately deciding whether to commit or rollback. Participants carry out transaction operations and either commit or rollback based on the coordinator’s instructions.
2. TCC (Try-Confirm-Cancel): TCC is a distributed transaction pattern that involves trying first, confirming, and then canceling. It breaks down one large transaction into three small stages: Try, Confirm, and Cancel. Each stage has its own set of operations and logic.
3. Best-Effort Delivery: Best-Effort Delivery is a distributed transaction pattern based on message queues. When a system needs to interact with other systems, it sends operation requests to a message queue, and then other systems retrieve the requests from the message queue and perform the operations. If the operation fails, the system can ensure eventual consistency through a retry mechanism.
4. XA transactions: XA transactions are a standard protocol for distributed transactions that define a Transaction Manager to coordinate transactions across multiple Resource Managers. JTA (Java Transaction API) in Java provides support for XA transactions.

The above are just some common ways of implementing distributed transactions, and the specific choice depends on the system requirements and architectural design.