java - 错误 org.hibernate.MappingException : Unknown entity: com. csm.app1st.model.User

Question

我正在尝试使用 java 和 hibernate 开发我的第一个简单的 Web 应用程序，但它不起作用。

这是错误:

 org.hibernate.MappingException: Unknown entity: com.csm.app1st.model.User
    at org.hibernate.metamodel.internal.MetamodelImpl.entityPersister(MetamodelImpl.java:620)
    at org.hibernate.internal.SessionImpl.getEntityPersister(SessionImpl.java:1606)
    at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:104)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:192)
    at org.hibernate.event.internal.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:38)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:177)
    at org.hibernate.event.internal.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:32)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:73)
    at org.hibernate.internal.SessionImpl.fireSave(SessionImpl.java:675)
    at org.hibernate.internal.SessionImpl.save(SessionImpl.java:667)
    at org.hibernate.internal.SessionImpl.save(SessionImpl.java:662)
    at com.csm.app1st.controller.AddUser.doPost(AddUser.java:40)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:650)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:218)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:956)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:442)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1083)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:640)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:318)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Unknown Source)

这是我的代码

添加用户:

package com.csm.app1st.controller;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;

import com.csm.app1st.model.User;

/**
 * Servlet implementation class AddUser
 */
@WebServlet(description = "Create new user Servlet", urlPatterns = { "/CreateUser.do" })
public class AddUser extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) 
            throws ServletException, IOException {

        Configuration config = new Configuration().configure();
        ServiceRegistry servReg = new StandardServiceRegistryBuilder().applySettings(config.getProperties()).build();
        SessionFactory factory = config.buildSessionFactory(servReg);

        Session session = factory.openSession();
        session.beginTransaction();
        User u = new User(request.getParameter("firstname"), request.getParameter("lastname"), request.getParameter("country"));
        session.save(u);
        session.getTransaction().commit();
        session.close();

        RequestDispatcher view = request.getRequestDispatcher("useradd.jsp");
        view.forward(request, response);
    }

}

用户

    package com.csm.app1st.model;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "user")

public class User {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name="user_id", nullable=false, unique=true)
private int id;

@Column(name="firstname", length=40, nullable=false)
private String firstname;

@Column(name="lastname", length=40, nullable=false)
private String lastname;

@Column(name="country", length=40, nullable=true)
private String country;

public User(String firstname, String lastname, String country) {
    this.firstname = firstname;
    this.lastname = lastname;
    this.country = country;
}

get & set...

}

hibernate 配置文件

 <hibernate-configuration>
    <session-factory>

        <property name="hibernate.dialect">org.hibernate.dialect.PostgreSQLDialect</property>
        <property name="hibernate.connection.driver_class">org.postgresql.Driver</property>

        <property name="hibernate.connection.url">jdbc:postgresql://localhost:5432/firstapp</property>
        <property name="hibernate.connection.username">postgres</property>
        <property name="hibernate.connection.password">password</property>
        <property name="show_sql">false</property>

        <mapping class="com.csm.app1st.model.User" />

    </session-factory>
</hibernate-configuration>

我不知道为什么它不起作用。 你能帮我吗？

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>first_project</groupId>
  <artifactId>first_project</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>war</packaging>
  <build>
    <sourceDirectory>src</sourceDirectory>
    <resources>
      <resource>
        <directory>src</directory>
        <excludes>
          <exclude>**/*.java</exclude>
        </excludes>
      </resource>
    </resources>
    <plugins>
      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.1</version>
        <configuration>
          <source>1.8</source>
          <target>1.8</target>
        </configuration>
      </plugin>
      <plugin>
        <artifactId>maven-war-plugin</artifactId>
        <version>2.4</version>
        <configuration>
          <warSourceDirectory>WebContent</warSourceDirectory>
          <failOnMissingWebXml>false</failOnMissingWebXml>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>

Answer 1

我尝试替换 adduser.java 文件中的以下代码

Configuration config = new Configuration().configure(); 
ServiceRegistry servReg = new StandardServiceRegistryBuilder().applySettings(config.getProperties()).build(); 
SessionFactory factory = config.buildSessionFactory(servReg);

与

SessionFactory factory = new Configuration().configure()
                .buildSessionFactory();

休息都一样。这对我有用。