我想使用 netbeans 和 java DB 将数据从表单输入到数据库中。我的问题是我无法弄清楚如何将用户在表单中输入的数据传递到数据库。
我尝试创建一个实体类并通过它连接它，但根据我遵循的指南，我最终可以访问整个数据库，而不仅仅是表单
编辑：这是一个学校项目，至少还没有教过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();
}
}
}
这就是坚持.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>
结果是有一个表单，虽然它有效，但它不会在数据库中插入任何数据。
亲爱的哈利·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，您使用Hibernate或其他实现JPA规范的框架。
通常你会使用 maven 项目，在 pom.xml 文件中，你有一些休眠依赖项，如下所示：
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>${hibernate.core.version}</version>
</dependency>
通常存储整个对象
您在此处输入的代码：
utx.begin();
em = getEntityManager();
em.persist(room);
utx.commit();
看起来您正在使用一些 JPA 实现。 但是为了了解您的问题，查看 pom.xml 或 hibernate.properties 等配置文件会有所帮助。
您可以完整上传代码以更好地理解。 Y 与您分享我学习休眠并将数据存储在 mysql 数据库中的一些项目 https://github.com/marianocali/concesionario
这是一个使用 Hibernate 的项目的简单示例，您可以在其中看到与具有所有配置的项目类似的代码。
文件持久性.xml创建数据库中的 java 类和表之间的映射。
已编辑：您的持久性.xml文件必须包含有关数据库连接的信息： 请看这两个例子： 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:)投票回答 如果您需要更多帮助，请告诉我
问候。
马里亚诺