Question

我想使用Netbeans和Java DB将数据从表单输入数据库。我的问题是我无法弄清楚如何将用户以表格形式输入的数据传递给数据库。

我尝试创建一个实体类并通过它进行连接，但是根据我遵循的指南，我最终可以访问整个数据库，而不仅仅是表格

编辑：这是一个学校项目，至少到目前为止我还没有听说过JDBC。


<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:h="http://xmlns.jcp.org/jsf/html"
      xmlns:f="http://xmlns.jcp.org/jsf/core">
    <h:head>
        <title>Registration</title>
        <h:outputStylesheet name="css/jsfcrud.css"/>
        <h:outputStylesheet library="css" name="styles.css"/>
    </h:head>
    <h:body>
        <h3>Registration Page</h3>
        <h:form>
            <h:panelGrid columns="3"
                         columnClasses="rightalign,leftalign,leftali
                         gn">
                <h:outputLabel value="Category: " for="category"/>
                <h:selectOneMenu id="category" label="Category"
                                 value="#{registrationBean.
                                          category}" >
                    <f:selectItem itemLabel="Simple." itemValue="Simple"/>
                    <f:selectItem itemLabel="Suite." itemValue="Suite"/>
                    <f:selectItem itemLabel="Luxurious" itemValue="Luxurious"/>
                </h:selectOneMenu>
                <h:message for="category"/>
                <h:outputLabel value="People: " for="people"/>
                <h:selectOneMenu id="people" label="People"
                                 value="#{registrationBean.
                                          people}" >
                    <f:selectItem itemLabel="Mr." itemValue="1"/>
                    <f:selectItem itemLabel="Mrs." itemValue="2"/>
                    <f:selectItem itemLabel="Miss" itemValue="3"/>
                    <f:selectItem itemLabel="Miss" itemValue="4"/>
                </h:selectOneMenu>
                <h:message for="people"/>
                <h:outputLabel value="Duration:" for="duration"/>
                <h:inputText id="duration" label="Duration"
                             required="true"
                             value="#{registrationBean.duration}" />

                <h:message for="duration" />
                <h:panelGroup/>
                <h:commandButton id="register" value="Register"
                                 action="confirmation" />
            </h:panelGrid>
        </h:form>
        <br />
        <h:link outcome="/room/List" value="Show All Room Items"/>
    </h:body>

</html>


@Entity
public class Room implements Serializable {

    @Id
    @Basic(optional = false)
    @NotNull
    @Column(nullable = false)
    private Integer id;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 20)
    @Column(nullable = false, length = 20)
    private String category;
    @Basic(optional = false)
    @NotNull
    @Column(nullable = false)
    private int people;
    @Basic(optional = false)
    @NotNull
    @Column(nullable = false)
    private int duration;

    private static final long serialVersionUID = 1L;
    @Id

    public String getCategory() {
        return category;
    }

    public void setCategory(String category) {
        this.category = category;
    }

    public Integer getPeople() {
        return people;
    }

    public void setPeople(Integer people) {
        this.people = people;
    }

    public Integer getDuration() {
        return duration;
    }

    public void setDuration(Integer duration) {
        this.duration = duration;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    @Override
    public int hashCode() {
        int hash = 0;
        hash += (id != null ? id.hashCode() : 0);
        return hash;
    }

    @Override
    public boolean equals(Object object) {
        // TODO: Warning - this method won't work in the case the id fields are not set
        if (!(object instanceof Room)) {
            return false;
        }
        Room other = (Room) object;
        if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) {
            return false;
        }
        return true;
    }

    @Override
    public String toString() {
        return "com.ensode.jsf.hotelreservations.Room[ id=" + id + " ]";
    }

    public Room() {
    }

    public Room(Integer id) {
        this.id = id;
    }

    public Room(Integer id, String category, int people, int duration) {
        this.id = id;
        this.category = category;
        this.people = people;
        this.duration = duration;
    }


}

public class RoomJpaController implements Serializable {

    public RoomJpaController(UserTransaction utx, EntityManagerFactory emf) {
        this.utx = utx;
        this.emf = emf;
    }
    private UserTransaction utx = null;
    private EntityManagerFactory emf = null;

    public EntityManager getEntityManager() {
        return emf.createEntityManager();
    }

    public void create(Room room) throws RollbackFailureException, Exception {
        EntityManager em = null;
        try {
            utx.begin();
            em = getEntityManager();
            em.persist(room);
            utx.commit();
        } catch (Exception ex) {
            try {
                utx.rollback();
            } catch (Exception re) {
                throw new RollbackFailureException("An error occurred attempting to roll back the transaction.", re);
            }
            throw ex;
        } finally {
            if (em != null) {
                em.close();
            }
        }
    }

    public void edit(Room room) throws NonexistentEntityException, RollbackFailureException, Exception {
        EntityManager em = null;
        try {
            utx.begin();
            em = getEntityManager();
            room = em.merge(room);
            utx.commit();
        } catch (Exception ex) {
            try {
                utx.rollback();
            } catch (Exception re) {
                throw new RollbackFailureException("An error occurred attempting to roll back the transaction.", re);
            }
            String msg = ex.getLocalizedMessage();
            if (msg == null || msg.length() == 0) {
                Integer id = room.getId();
                if (findRoom(id) == null) {
                    throw new NonexistentEntityException("The room with id " + id + " no longer exists.");
                }
            }
            throw ex;
        } finally {
            if (em != null) {
                em.close();
            }
        }
    }

    public void destroy(Long id) throws NonexistentEntityException, RollbackFailureException, Exception {
        EntityManager em = null;
        try {
            utx.begin();
            em = getEntityManager();
            Room room;
            try {
                room = em.getReference(Room.class, id);
                room.getId();
            } catch (EntityNotFoundException enfe) {
                throw new NonexistentEntityException("The room with id " + id + " no longer exists.", enfe);
            }
            em.remove(room);
            utx.commit();
        } catch (Exception ex) {
            try {
                utx.rollback();
            } catch (Exception re) {
                throw new RollbackFailureException("An error occurred attempting to roll back the transaction.", re);
            }
            throw ex;
        } finally {
            if (em != null) {
                em.close();
            }
        }
    }

    public List<Room> findRoomEntities() {
        return findRoomEntities(true, -1, -1);
    }

    public List<Room> findRoomEntities(int maxResults, int firstResult) {
        return findRoomEntities(false, maxResults, firstResult);
    }

    private List<Room> findRoomEntities(boolean all, int maxResults, int firstResult) {
        EntityManager em = getEntityManager();
        try {
            CriteriaQuery cq = em.getCriteriaBuilder().createQuery();
            cq.select(cq.from(Room.class));
            Query q = em.createQuery(cq);
            if (!all) {
                q.setMaxResults(maxResults);
                q.setFirstResult(firstResult);
            }
            return q.getResultList();
        } finally {
            em.close();
        }
    }

    public Room findRoom(Integer id) {
        EntityManager em = getEntityManager();
        try {
            return em.find(Room.class, id);
        } finally {
            em.close();
        }
    }

    public int getRoomCount() {
        EntityManager em = getEntityManager();
        try {
            CriteriaQuery cq = em.getCriteriaBuilder().createQuery();
            Root<Room> rt = cq.from(Room.class);
            cq.select(em.getCriteriaBuilder().count(rt));
            Query q = em.createQuery(cq);
            return ((Long) q.getSingleResult()).intValue();
        } finally {
            em.close();
        }
    }

}

这是persistance.xml

<?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="HotelReservationsPU" transaction-type="JTA">
    <jta-data-source>java:app/roomintro</jta-data-source>
    <exclude-unlisted-classes>false</exclude-unlisted-classes>
    <properties>
      <property name="javax.persistence.schema-generation.database.action" value="drop-and-create"/>
    </properties>
  </persistence-unit>
</persistence>

结果是具有一种在运行时不会在数据库中插入任何数据的表单。

Answer 1

亲爱的哈里斯·洛伦扎托斯：

在普通的Java项目中，为了将数据存储在数据库中，可以使用Hibernate或其他实现JPA规范的框架。

通常，您将使用maven项目，并且在pom.xml文件中，您将具有一些像这样的休眠依赖项：

    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>${hibernate.core.version}</version>
    </dependency>

通常您存储整个对象

您在此处输入的代码：

    utx.begin();
    em = getEntityManager();
    em.persist(room);
    utx.commit();

好像您正在使用某些JPA实现。但是，为了了解您的问题，有助于查看pom.xml或hibernate.properties之类的配置文件。

您可以完整地上传代码以更好地理解。与您分享一些我学习过Hibernate的项目并将数据存储在mysql数据库中 https://github.com/marianocali/concesionario

这是一个使用Hibernate的项目的简单示例，您可以在所有配置下看到与项目相似的代码。

文件persistence.xml创建Java类与数据库中的表之间的映射。

已编辑： 您的persistence.xml文件必须具有有关数据库连接的信息：看一下这两个例子：https://github.com/marianocali/concesionario/blob/master/src/main/resources/META-INF/persistence.xml

https://gist.github.com/halyph/2990769

您必须在文件中添加所有这些信息。

如果这对您有帮助，请对答案进行投票:) 如果您需要更多帮助，请告诉我
问候。
马里亚诺

如何在NetBeans中将数据从xhtml表单插入Java DB？

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