Question

我使用注释@PersistenceUnit来获取EntityManagerFactory的实例，但经过多次测试后，它不起作用。我一直在寻找理论，例子等，但没有成功。理论似乎很容易，但我无法看到我的代码出现问题或缺少什么。

我正在使用的bean的代码是：

import ...

@Stateless
@TransactionManagement(TransactionManagementType.BEAN)
public class TopBean extends UserTransactionWrapper implements TopService
{

    @Inject
    Logger logger = LoggerFactory.getLogger(this.getClass());

    @PersistenceUnit(unitName="puTop")
    private EntityManagerFactory entityManagerFactory;

    @Override
    public OperationResult<Boolean> retrieve()
    {
        return execute();
    }

    protected OperationResult<Boolean> doRetrieve()
                                                                                 throws Exception
    {
            OperationResult<Boolean> operationResult = new OperationResult<Boolean>();
            EntityManager entityManager = entityManagerFactory.createEntityManager();

            long id = 5;
            Node node = new Node(id, "Host.One", NodeType.SWITCH, true);
            entityManager.persist(node);
            operationResult.setData(node.getId() == id);

            return operationResult;
    }

    @Override
    protected Logger getLogger()
    {
        return logger;
    }

}

UserTransactionWrapper类仅包含初始化函数获取的用户事务的代码：

private UserTransaction getTransaction()
                                                                    throws NamingException
{
    Context context = new InitialContext();
    return (UserTransaction)context.lookup("java:comp/UserTransaction");
}

使用@Resource注入用户事务不起作用，所以我必须这样做。

我的persistence.xml是：

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1" xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
    <persistence-unit name="puTop" transaction-type="JTA">
        <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
        <jta-data-source>jdbc/Top</jta-data-source>
        <class>...</class>
        <exclude-unlisted-classes>true</exclude-unlisted-classes>
    </persistence-unit>
</persistence>

提前谢谢！

马努

我正在添加UserTransactionWrapper类的代码：

public abstract class UserTransactionWrapper extends Wrapper
{

    @SuppressWarnings("unchecked")
    protected <E> OperationResult<E> execute(Object... parameters)
    {
        OperationResult<E> operationResult = new OperationResult<E>();
        Method doMethod = findMethod();
        Logger logger = getLogger();
    // If the method exists...
        if (doMethod != null)
        {
            UserTransaction userTransaction = null; 
            try
            {

            // Initializing user transaction
            // =============================

                userTransaction = getTransaction();
                userTransaction.begin();

            // Accomplishment of the operation
            // ===============================

                int parametersN = (parameters != null ? parameters.length : 0);
                Object[] auxiliary = new Object[parametersN];
                for (int i = parametersN; (--i) >= 0;) auxiliary[i] = parameters[i];

                doMethod.setAccessible(true);
                operationResult = (OperationResult<E>)doMethod.invoke(this, auxiliary);

            // Completion of the transaction
            // =============================

                userTransaction.commit();

            }
            catch (Exception primary)
            {
                try
                {
                // If transaction is defined...
                    if (userTransaction != null) userTransaction.rollback();

                    boolean invocationError = primary instanceof InvocationTargetException; 
                // If the invoked method has thrown an exception...
                    if (invocationError)
                    {
                        Throwable cause = primary.getCause();
                        cause = (cause != null ? cause : primary);
                        operationResult.setError(cause);
                        logger.error(INVOCATION_ERROR, cause);
                    }
                // If it hasn't done...
                    else
                    {
                        operationResult.setError(primary);
                        logger.error(UNEXPECTED_ERROR, primary);
                    }
                }
                catch (Exception secondary)
                {
                    logger.error(UNEXPECTED_ERROR, secondary);
                }
            }
        }
    // If it doesn't exist...
        else
        {
            operationResult = new OperationResult<E>();
            operationResult.setError(new NoSuchMethodException());
        }

        return operationResult;
    }

    private UserTransaction getTransaction()
                                                                        throws NamingException
    {
        Context context = new InitialContext();
        return (UserTransaction)context.lookup("java:comp/UserTransaction");
    }

}

Answer 1

我想问题是你试图注入EntityManagerFactory，但是在使用JTA时你必须注入EntityManager。

将您的代码更改为：

@PersistenceUnit(unitName="puTop")
private EntityManager entityManager;

并直接使用EntityManager。

如果您想要使用事务类型＆＃34; RESOURCE_LOCAL＆＃34;然后将persistence.xml更改为以下内容：

<persistence-unit name="puTop" transaction-type="RESOURCE_LOCAL">

无论如何，没有理由进行这种手动交易管理。
您可以像这样编写代码：

@Stateless
public class TopBean
{
    @PersistenceUnit(unitName="puTop")
    private EntityManager entityManager;

    public Node persist() {

        Node node = new Node(5, "Host.One", NodeType.SWITCH, true);
        entityManager.persist(node);
        return node;
    }
}

这就是坚持实体所需的一切......

@PersistenceUnit不起作用（Java EE 7，Glassfish 4.1）

1 个答案: