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10.2 Transaction Templates

Transaction templates wrap a local code block with standard transaction control: begin first, commit on normal completion, and roll back on an exception or rollback marker.

Suitable For​

  • Wrap a code block in a plain Java program.
  • Avoid creating proxies for @Transactional.
  • Avoid repeating try/catch/finally.

Not Suitable For​

  • A Service method defines the boundary and proxies are already available.
  • Multiple transaction statuses need manual commit or rollback ordering.

This page uses dbVisitor's transaction template, not Spring's class of the same name. execute declares Throwable; callers must catch or declare it. Sequence SQL examples apply to databases supporting NEXT VALUE FOR, such as H2.

Basic Usage​

Create TransactionTemplate
import javax.sql.DataSource;
import net.hasor.dbvisitor.transaction.TransactionManager;
import net.hasor.dbvisitor.transaction.TransactionTemplate;
import net.hasor.dbvisitor.transaction.TransactionTemplateManager;
import net.hasor.dbvisitor.transaction.support.TransactionHelper;

DataSource dataSource = ...;
TransactionManager txManager = TransactionHelper.txManager(dataSource);
TransactionTemplate txTemplate = new TransactionTemplateManager(txManager);
Return a Result from a Transaction
Long orderId = txTemplate.execute(tranStatus -> {
    Long newOrderId = jdbcTemplate.queryForObject(
            "select next value for seq_order",
            Long.class
    );

    jdbcTemplate.executeUpdate(
            "insert into orders(id, user_id) values(?, ?)",
            new Object[] { newOrderId, userId }
    );
    jdbcTemplate.executeUpdate(
            "insert into order_item(order_id, sku_id) values(?, ?)",
            new Object[] { newOrderId, skuId }
    );
    return newOrderId;
});

Behavior:

  • On normal callback return, the template commits and returns newOrderId from execute.
  • When the callback throws, the template marks the transaction for rollback and rethrows.

Code Blocks Without Results​

Use TransactionCallbackWithoutResult
import net.hasor.dbvisitor.transaction.TransactionCallbackWithoutResult;

txTemplate.execute((TransactionCallbackWithoutResult) tranStatus -> {
    jdbcTemplate.executeUpdate(
            "delete from order_item where order_id = ?",
            orderId
    );
    jdbcTemplate.executeUpdate(
            "delete from orders where id = ?",
            orderId
    );
});

Request Rollback​

To request rollback without throwing an exception, call tranStatus.setRollback() in the callback.

Roll Back on Validation Failure and Return a Business Result
Boolean success = txTemplate.execute(tranStatus -> {
    int updated = jdbcTemplate.executeUpdate(
            "update sku_stock set quantity = quantity - ? where sku_id = ? and quantity >= ?",
            new Object[] { quantity, skuId, quantity }
    );

    if (updated == 0) {
        tranStatus.setRollback();
        return false;
    }

    jdbcTemplate.executeUpdate(
            "insert into stock_log(sku_id, quantity) values(?, ?)",
            new Object[] { skuId, quantity }
    );
    return true;
});

Behavior:

  • With sufficient stock, the stock deduction and log commit together; the result is true.
  • With insufficient stock, the transaction rolls back without throwing and returns false.

Specify Propagation and Isolation​

Write Audit Logs in an Independent Transaction
import net.hasor.dbvisitor.transaction.Isolation;
import net.hasor.dbvisitor.transaction.Propagation;

txTemplate.execute(tranStatus -> {
    jdbcTemplate.executeUpdate(
            "insert into order_audit(order_id, action) values(?, ?)",
            new Object[] { orderId, "CREATE" }
    );
    return null;
}, Propagation.REQUIRES_NEW, Isolation.READ_COMMITTED);

Inside an outer transaction, REQUIRES_NEW suspends it and opens a new connection for the audit transaction. The outer transaction resumes after the audit transaction commits or rolls back.

Obtain TransactionTemplate​

Plain Java Programs
TransactionManager txManager = TransactionHelper.txManager(dataSource);
TransactionTemplate txTemplate = new TransactionTemplateManager(txManager);
Dependency Injection
public class OrderService {
    // @Inject                 < Guice, Solon and Hasor
    // @Resource or @Autowired < Spring
    private TransactionTemplate txTemplate;
}

Related integrations:

Further Reading​