事务同步器

君子择交，莫恶于易与，莫善于胜己。——王夫之

有时候我们需要在事务执行前后执行一些代码，这时候可以使用事务同步器

import org.springframework.transaction.support.TransactionSynchronization;

public class MyTransactionSynchronization implements TransactionSynchronization {

    @Override
    public void beforeCommit(boolean readOnly) {
        // 事务提交之前的逻辑
        System.out.println("Before commit");
    }

    @Override
    public void beforeCompletion() {
        // 事务完成之前的逻辑
        System.out.println("Before completion");
    }

    @Override
    public void afterCommit() {
        // 事务成功提交之后的逻辑
        System.out.println("After commit");
    }

    @Override
    public void afterCompletion(int status) {
        // 事务完成之后的逻辑
        if (status == STATUS_COMMITTED) {
            System.out.println("Transaction committed");
        } else if (status == STATUS_ROLLED_BACK) {
            System.out.println("Transaction rolled back");
        }
    }
}

注册事务同步器

import org.springframework.transaction.support.TransactionSynchronization;
import org.springframework.transaction.support.TransactionSynchronizationManager;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
@RequestMapping("/api")
public class MyController {

    @GetMapping("/test")
    public String test() {
        // 检查当前事务是否已经注册了该同步器
        List<TransactionSynchronization> synchronizations = TransactionSynchronizationManager.getSynchronizations();
        boolean alreadyRegistered = synchronizations.stream()
                .anyMatch(sync -> sync instanceof MyTransactionSynchronization);

        if (!alreadyRegistered) {
            // 只在未注册时注册新的事务同步器
            TransactionSynchronizationManager.registerSynchronization(new MyTransactionSynchronization());
        }

        // 执行其他逻辑
        return "Test completed";
    }
}

class MyTransactionSynchronization implements TransactionSynchronization {
    @Override
    public void afterCompletion(int status) {
        if (status == STATUS_COMMITTED) {
            System.out.println("Transaction committed");
        } else {
            System.out.println("Transaction rolled back");
        }
    }

    @Override
    public void beforeCommit(boolean readOnly) {
        System.out.println("Before commit");
    }

    @Override
    public void beforeCompletion() {
        System.out.println("Before completion");
    }

    @Override
    public void afterCommit() {
        System.out.println("After commit");
    }
}