与Guice和JDBC的事务-解决方案讨论

在我的应用程序中，我需要将纯JDBC与Guice一起使用。但是，Guice不提供任何内置支持来管理事务。guice persist只提供基于JPA的支持，我不能使用JPA

因此，我尝试实现一个简单的解决方案，用Guice和JDBC管理事务。以下是第一个版本：

使用TransactionHolder存储每个线程的事务

公共类JdbcTransactionHolder{

private static ThreadLocal<JdbcTransaction> currentTransaction = new ThreadLocal<JdbcTransaction>();

public static void setCurrentTransaction(JdbcTransaction transaction) {
    currentTransaction.set(transaction);
}

public static JdbcTransaction getCurrentTransaction() {
    return currentTransaction.get();
}

public static void removeCurrentTransaction() {
    currentTransaction.remove();
}

}

为数据源实现一个包装器，如果事务已启动，该包装器可以从事务持有者获取当前连接：

公共类JdbcDataSource实现了DataSource{

private final static org.slf4j.Logger logger = LoggerFactory.getLogger(JdbcDataSource.class);

private DataSource dataSource;

public JdbcDataSource(DataSource dataSource) {
    this.dataSource = dataSource;
}

@Override
public PrintWriter getLogWriter() throws SQLException {
    return dataSource.getLogWriter();
}

@Override
public int getLoginTimeout() throws SQLException {

    return dataSource.getLoginTimeout();
}

@Override
public Logger getParentLogger() throws SQLFeatureNotSupportedException {

    return dataSource.getParentLogger();
}

@Override
public void setLogWriter(PrintWriter out) throws SQLException {
    this.dataSource.setLogWriter(out);
}

@Override
public void setLoginTimeout(int seconds) throws SQLException {
    this.dataSource.setLoginTimeout(seconds);
}

@Override
public boolean isWrapperFor(Class<?> arg0) throws SQLException {
    return this.isWrapperFor(arg0);
}

@Override
public <T> T unwrap(Class<T> iface) throws SQLException {

    return this.unwrap(iface);
}

@Override
public Connection getConnection() throws SQLException {
    JdbcTransaction transaction = JdbcTransactionHolder.getCurrentTransaction();
    if(transaction != null) {
        // we get the connection from the transaction
        logger.debug("Transaction exists for the thread: {}.", Thread.currentThread());
        return transaction.getConnection();
    }
    Connection conn = this.dataSource.getConnection();
    conn.setAutoCommit(false);
    return conn;
}

@Override
public Connection getConnection(String username, String password)
        throws SQLException {
    JdbcTransaction transaction = JdbcTransactionHolder.getCurrentTransaction();
    if(transaction != null) {
        // we get the connection from the transaction
        logger.debug("Transaction exists for the thread: {}.", Thread.currentThread());
        return transaction.getConnection();
    }

    return this.dataSource.getConnection(username, password);
}

然后实现TransactionalMethodInterceptor来管理带有事务注释的方法的事务：

公共类TransactionalMethodInterceptor实现MethodInterceptor{

private final static Logger logger = LoggerFactory.getLogger(TransactionalMethodInterceptor.class);

@Inject
private JdbcTransactionManager transactionManager;

@Override
public Object invoke(MethodInvocation method) throws Throwable {

    try {
        // Start the transaction
        transactionManager.begin();
        logger.debug("Start to invoke the method: " + method);

        Object result = method.proceed();
        logger.debug("Finish invoking the method: " + method);
        transactionManager.commit();
        return result;
    } catch (Exception e) {
        logger.error("Failed to commit transaction!", e);
        try {
            transactionManager.rollback();

        }
        catch(Exception ex) {
            logger.warn("Cannot roll back transaction!", ex);
        }
        throw e;
    }
}

}

最后，将代码放在一起，以便Guice可以注入实例：

bind(DataSource.class).toProvider(DataSourceProvider.class).in(Scopes.SINGLETON);

bind(TransactionManager.class).to(JdbcTransactionManager.class);
TransactionalMethodInterceptor transactionalMethodInterceptor = new TransactionalMethodInterceptor();
requestInjection(transactionalMethodInterceptor);
bindInterceptor(Matchers.any(), Matchers.annotatedWith(Transactional.class), transactionalMethodInterceptor);


bind(TestDao.class).to(JdbcTestDao.class);
bind(TestService.class).to(TestServiceImpl.class);

我使用c3p0作为数据源池。因此，它在我的测试中运行良好

我发现另一个相关问题：

但到目前为止，我还没有找到任何类似的方法，除了SpringFramework中的一些方法。但是，即使是Spring中的实现也似乎相当复杂

我想问一下，是否有人对这个解决方案有任何建议

---

谢谢。

记住一件事：不使用RuntimeException，而是需要定义特定于处理错误的异常。

private final static Logger logger = LoggerFactory.getLogger(TransactionalMethodInterceptor.class);

@Inject
private JdbcTransactionManager transactionManager;

@Override
public Object invoke(MethodInvocation method) throws Throwable {

    try {
        // Start the transaction
        transactionManager.begin();
        logger.debug("Start to invoke the method: " + method);

        Object result = method.proceed();
        logger.debug("Finish invoking the method: " + method);
        transactionManager.commit();
        return result;
    } catch (Exception e) {
        logger.error("Failed to commit transaction!", e);
        try {
            transactionManager.rollback();

        }
        catch(Exception ex) {
            logger.warn("Cannot roll back transaction!", ex);
        }
        throw e;
    }
}

bind(DataSource.class).toProvider(DataSourceProvider.class).in(Scopes.SINGLETON);

bind(TransactionManager.class).to(JdbcTransactionManager.class);
TransactionalMethodInterceptor transactionalMethodInterceptor = new TransactionalMethodInterceptor();
requestInjection(transactionalMethodInterceptor);
bindInterceptor(Matchers.any(), Matchers.annotatedWith(Transactional.class), transactionalMethodInterceptor);


bind(TestDao.class).to(JdbcTestDao.class);
bind(TestService.class).to(TestServiceImpl.class);