Java 冬眠+；PostgreSQL引发异常：未知实体

我使用

jersey+hibernate

为restful

webservice

编写了一个java maven项目，并出现以下

错误

：

javax.servlet.ServletException:org.hibernate.MappingException: 未知实体：org.asad.dto.logindetail

org.glassfish.jersey.servlet.WebComponent.service（WebComponent.java:419）

org.glassfish.jersey.servlet.ServletContainer.service（ServletContainer.java: 381) org.glassfish.jersey.servlet.ServletContainer.service（ServletContainer.java:344）

org.glassfish.jersey.servlet.ServletContainer.service（ServletContainer.java: 221）

hibernate.cfg.xml文件：

 <?xml version='1.0' encoding='utf-8'?>

<!DOCTYPE hibernate-configuration PUBLIC

        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"

        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">


<hibernate-configuration>


    <session-factory>


        <!-- Database connection settings -->

        <property name="connection.driver_class">org.postgresql.Drive</property>

        <property 
    name="connection.url">jdbc:postgresql://localhost:5432/logindb</property>

    <property name="connection.username">postgres</property>

        <property name="connection.password">project</property>

        <!-- JDBC connection pool (use the built-in) -->

        <property name="connection.pool_size">1</property>


        <!-- SQL dialect -->

        <property 
    name="dialect">org.hibernate.dialect.PostgreSQLDialect</property>

        <!-- Disable the second-level cache  -->

    <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>


        <!-- Echo all executed SQL to stdout -->

        <property name="show_sql">true</property>

        <!-- Drop and re-create the database schema on startup -->

        <property name="hbm2ddl.auto">update</property>

        <propertyname="connection.driver_class">org.postgresql.Driver</property>

        <!-- Names the annotated entity class -->

        <mapping class="org.asad.dto.logindetail"/>

    </session-factory>

</hibernate-configuration>

 @Entity
     @Table (name = "logidetail")  public class logindetail {

    @Id

    int userId;

    String name;

    String password;


    public void setUserId(int i){

        this.userId = i;

    }

    public int getUserId(){

        return userId;

    }

    public void setName(String name){

        this.name  = name;

    }

    public String getName(){

        return name;

    }

    public void setPassword(String pass){

        this.password = pass;

    }

    public String getPassword(){

        return password;

    }}

 package org.asad.login.login.loginservice; 

import java.util.ArrayList;

import javax.management.Query;

import javax.validation.Validation;

import javax.validation.Validator;

import javax.validation.ValidatorFactory;

import org.asad.dto.logindetail;

import org.hibernate.SessionFactory;

import org.hibernate.cfg.Configurationimport org.hibernate.classic.Session;

public class LoginService{

    SessionFactory sessionFactory = null;

    Session session = null;

    public String getDatabaseUser(){

        logindetail user = null;

        String name=null;try{

        sessionFactory = new Configuration().configure().buildSessionFactory();

        session = sessionFactory.openSession();

        session.beginTransaction();

        user = (logindetail)session.get(logindetail.class, 2);

        name = user.getName();

        session.getTransaction().commit();

        session.close();

    }catch(Exception e){

       e.printStackTrace();

     }

    return name;

        }}

主类：

 <?xml version='1.0' encoding='utf-8'?>

<!DOCTYPE hibernate-configuration PUBLIC

        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"

        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">


<hibernate-configuration>


    <session-factory>


        <!-- Database connection settings -->

        <property name="connection.driver_class">org.postgresql.Drive</property>

        <property 
    name="connection.url">jdbc:postgresql://localhost:5432/logindb</property>

    <property name="connection.username">postgres</property>

        <property name="connection.password">project</property>

        <!-- JDBC connection pool (use the built-in) -->

        <property name="connection.pool_size">1</property>


        <!-- SQL dialect -->

        <property 
    name="dialect">org.hibernate.dialect.PostgreSQLDialect</property>

        <!-- Disable the second-level cache  -->

    <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>


        <!-- Echo all executed SQL to stdout -->

        <property name="show_sql">true</property>

        <!-- Drop and re-create the database schema on startup -->

        <property name="hbm2ddl.auto">update</property>

        <propertyname="connection.driver_class">org.postgresql.Driver</property>

        <!-- Names the annotated entity class -->

        <mapping class="org.asad.dto.logindetail"/>

    </session-factory>

</hibernate-configuration>

 @Entity
     @Table (name = "logidetail")  public class logindetail {

    @Id

    int userId;

    String name;

    String password;


    public void setUserId(int i){

        this.userId = i;

    }

    public int getUserId(){

        return userId;

    }

    public void setName(String name){

        this.name  = name;

    }

    public String getName(){

        return name;

    }

    public void setPassword(String pass){

        this.password = pass;

    }

    public String getPassword(){

        return password;

    }}

 package org.asad.login.login.loginservice; 

import java.util.ArrayList;

import javax.management.Query;

import javax.validation.Validation;

import javax.validation.Validator;

import javax.validation.ValidatorFactory;

import org.asad.dto.logindetail;

import org.hibernate.SessionFactory;

import org.hibernate.cfg.Configurationimport org.hibernate.classic.Session;

public class LoginService{

    SessionFactory sessionFactory = null;

    Session session = null;

    public String getDatabaseUser(){

        logindetail user = null;

        String name=null;try{

        sessionFactory = new Configuration().configure().buildSessionFactory();

        session = sessionFactory.openSession();

        session.beginTransaction();

        user = (logindetail)session.get(logindetail.class, 2);

        name = user.getName();

        session.getTransaction().commit();

        session.close();

    }catch(Exception e){

       e.printStackTrace();

     }

    return name;

        }}

现在这个错误出现了

java.lang.NullPointerException

---

任何人都可以帮助我消除此错误，我将非常感谢：）

您能检查您是否导入了正确的

@Entity

注释吗

由于

@Entity

包含两个包，一个是

org.hibernate.annotations.Entity

，另一个是

javax.persistence.Entity

---

使用

javax.persistence.Entity

注释实体bean。不要导入

org.hibernate.annotations.Entity

请不要使用小写名称作为类名。但这不是问题所在。我没有看到您的类代码上面有包指令。但是您在hibernate配置中使用了一个包'org.asad.dto'。这可能就是问题所在。如果是，则将该类放入resp。包。检查

logindetail

的包是否与中提供的包相同。@PeterPaulKiefer好的，我以后会注意类名。该包已放入类中，但仍然存在错误。@barthel yes该包与映射类中提供的包相同。请告诉我们引发此异常的操作，并提供完整的stacktrace和Hibernate版本。另外，将hibernate的loglevel切换到debug/trace会更好地解释错误。它可以工作，但数据没有从数据库中提交，显示204无内容发布您的主要类内容，那么只有一个人可以提出建议。@尽快回答这个问题，因为它可能会帮助其他有类似问题的开发人员。它显示了你和我；-）提供一个完整的类文件（包括包和导入）是多么重要。幸运的是，Arpit有这么多的经验来正确回答问题。@Arpit我添加了这个类，请参见并提出建议me@Asad改为使用

logindeail

实体类。在保存问题之前，请检查格式和布局。