Question

我想在我的数据库中保留一个对象，我正在使用来自Guice的@Trasactional和@Inject来保存数据.... hibernate配置在ressources / meta-inf文件夹中的文件persistence.xml中声明....

import ca.model.jpa.user;
import com.google.inject.Inject;
import com.google.inject.persist.Transactional;

import javax.persistence.EntityManager;
import javax.ws.rs.*;


@Path("/test")
public class TestService {

    @Inject
    private EntityManager entityManager;

    @GET
    @Transactional
    public String persistUser() {

        // User
        User user = new User();
        user.setPseudoname("Anonymous");
        user.setAge(20);

        entityManager.persist(user);

        return null;
    }

当我调试代码时，entityManager始终为null ...在我的理解中，注入旨在启动entityManager。但它没有这样做！

如何更正我的代码？谢谢

这里是我的文件persistence.xml的内容：

<persistence xmlns="http://java.sun.com/xml/ns/persistence" version="1.0">

    <persistence-unit name="manager1" transaction-type="RESOURCE_LOCAL">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>

        <properties>

            <!--PostgreSQL-->
            <property name="hibernate.connection.driver_class" value="org.postgresql.Driver"/>
            <property name="hibernate.connection.url" value="jdbc:postgresql://localhost:5432/postgres"/>
            <property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect"/>
            <property name="hibernate.connection.username" value="postgres"/>
            <property name="hibernate.connection.password" value="postgres"/>
            <property name="hibernate.archive.autodetection" value="class"/>
            <property name="hibernate.id.new_generator_mappings" value="true"/>
            <property name="hibernate.hbm2ddl.auto" value="update"/>
            <property name="hibernate.ejb.metamodel.generation" value="disabled"/>
            <property name="hibernate.ejb.naming_strategy" value="org.hibernate.cfg.DefaultComponentSafeNamingStrategy"/>
            <property name="hibernate.show_sql" value="true"/>
        </properties>

    </persistence-unit>

</persistence>

Answer 1

你能分享你的persistence.xml吗？因为在此文件中，您可以声明实体管理器的事务类型。请确保您已正确列出。

这里还有一个不错的链接：http://piotrnowicki.com/2012/11/types-of-entitymanagers-application-managed-entitymanager/

Answer 2

您的EntityManager未注入。

您是否实施了持久性模块？

public class ExampleHibernateModule extends PrivateModule {

    @Override
    public void configure() {

        install(new JpaPersistModule("example-persistence-unit").properties(jpaProperties()));

        bind(ExampleAO.class).to(ExampleImpl.class);

        expose(ExampleDAO.class);

        Key<PersistFilter> key = Key.get(PersistFilter.class, ExamplePersistenceUnit.class);
        bind(key).to(PersistFilter.class);
        expose(key);
    }

    Properties jpaProperties() {

        Properties appProperties = PropertiesUtils.getApplicationProperties();
        Properties properties = new Properties();

        properties.put("hibernate.connection.driver_class", "org.postgresql.Driver");
        properties.put("hibernate.connection.url", appProperties.get("hibernate.connection.url"));
        properties.put("hibernate.connection.username", appProperties.get("hibernate.connection.username"));
        properties.put("hibernate.connection.password", appProperties.get("hibernate.connection.password"));
        properties.put("hibernate.connection.pool_size", "1");
        properties.put("hibernate.dialect", "org.hibernate.dialect.PostgreSQLDialect");
        properties.put("hibernate.hbm2ddl.auto", appProperties.get("hibernate.hbm2ddl.auto"));
        properties.put("hibernate.show_sql", appProperties.get("hibernate.show_sql"));
        properties.put("hibernate.format_sql", appProperties.get("hibernate.format_sql"));
        properties.put("hibernate.cache.use.query_cache", "true");
        properties.put("hibernate.cache.use_second_level_cache", "true");

        return properties;
    }
}

另一个实现示例： Hibernate with JPA Annotations and Guice

使用Hibernate和Guice持久化对象

2 个答案: