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這是一個類似的帖子，我之前見過關於這個異常的帖子，但我完全失去了。我還沒有使用JPA將實體持久化到數據庫，儘管我使用它從表中讀取沒有任何問題。我的設置是使用Glassfish 3.1.1的Netbeans 7.1，EclipseLink是我的持久性提供者。我有一個非常簡單的場景，我只是想測試在數據庫中寫入人員姓名和年齡並使用id自動遞增。它是一個MySql數據庫，包含字段：Id，FirstName和Age。我的繼承人代碼：對象：entity.ENTITY [id = null]不是已知的實體類型
網站的servlet採取姓名和年齡從HTML表單：
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String userPath = request.getServletPath();
if(userPath.equals("/addUser")){
//get request parameters from form
String name = request.getParameter("name");
String age = request.getParameter("age");
//set request attributes to be used by forwarded page
request.setAttribute("name", name);
request.setAttribute("age", age);
//create manager class to add person to database
Manager manager = new Manager();
manager.addPerson(name, age);
userPath = "/result";
}
// use RequestDispatcher to forward request internally
String url = "/WEB-INF/view" + userPath + ".jsp";
try {
request.getRequestDispatcher(url).forward(request, response);
} catch (Exception ex) {
ex.printStackTrace();
}
}
管理類，它的名字和年齡，創建一個人對象，並堅持它。
public class Manager {
private static final String PERSISTENCE_UNIT_NAME = "FormPU";
private static EntityManagerFactory factory;
public Manager() {
}
public void addPerson(String name, String age) {
factory = Persistence.createEntityManagerFactory(PERSISTENCE_UNIT_NAME);
EntityManager em = factory.createEntityManager();
Persons persons = new Persons();
persons.setName(name);
persons.setAge(age);
em.getTransaction().begin();
em.persist(persons);
em.getTransaction().commit();
em.close();
}
}
人實體類：
/**
*
* @author esmiala
*/
@Entity
@Table(name = "persons")
@XmlRootElement
@NamedQueries({
@NamedQuery(name = "Persons.findAll", query = "SELECT p FROM Persons p"),
@NamedQuery(name = "Persons.findById", query = "SELECT p FROM Persons p WHERE
p.id = :id"),
@NamedQuery(name = "Persons.findByFirstName", query = "SELECT p FROM Persons p
WHERE p.firstName = :firstName"),
@NamedQuery(name = "Persons.findByAge", query = "SELECT p FROM Persons p WHERE
p.age = :age")})
public class Persons implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Basic(optional = false)
@NotNull
@Column(name = "Id")
private Integer id;
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 255)
@Column(name = "FirstName")
private String firstName;
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 255)
@Column(name = "Age")
private String age;
public Persons() {
}
public Persons(Integer id) {
this.id = id;
}
public Persons(Integer id, String firstName, String age) {
this.id = id;
this.firstName = firstName;
this.age = age;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
@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 Persons)) {
return false;
}
Persons other = (Persons) 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 "entity.Persons[ id=" + id + " ]";
}
}
的persistence.xml
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com
/xml/ns/persistence/persistence_2_0.xsd">
<persistence-unit name="FormPU" transaction-type="JTA">
<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
<jta-data-source>jdbc/form</jta-data-source>
<exclude-unlisted-classes>false</exclude-unlisted-classes>
<properties/>
</persistence-unit>
</persistence>
注：我也試圖排除，非流通類的標籤設置爲true，列表班級分開，但也沒有工作。
例外：
WARNING: StandardWrapperValve[Controller]: PWC1406: Servlet.service() for servlet
Controller threw exception
java.lang.IllegalArgumentException: Object: entity.persons[ id=null ] is not a
known entity type.
atorg.eclipse.persistence.internal.sessions.UnitOfWorkImpl.registerNewObject
ForPersist(UnitOfWorkImpl.java:4141)
atorg.eclipse.persistence.internal.jpa.EntityManagerImpl.
persist(EntityManagerImpl.java:368)
at manager.Manager.addPerson(Manager.java:36)
at controller.Controller.doPost(Controller.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:754)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1523)
...等等。任何幫助將不勝感激！
我刪除了實體類和持久性xml文件，並使用Netbeans Entity Classes from Database嚮導生成了新文件。它產生以下但仍然不起作用。生病編輯在新的實體類... – 2012-02-02 11:54:10