Hibernate buildSessionFactory() 异常

Question

我在 hibernate 方面遇到了严重的问题。我遵循了各种书籍和在线教程，但我得到了同样的异常“ExceptionInInitializerError”，显然是由 HibernateUtil.java 行抛出的

SessionFactory sf = cfg.configure().buildSessionFactory();

我的 Tomcat 日志显示以下内容:

Caused by: java.lang.ExceptionInInitializerError
at de.marcelstuht.nerven2.server.HibernateUtil.buildSessionFactory(HibernateUtil.java:23)
at de.marcelstuht.nerven2.server.HibernateUtil.<clinit>(HibernateUtil.java:8)
at de.marcelstuht.nerven2.shared.model.Account.<init>(Account.java:52)
at de.marcelstuht.nerven2.server.GreetingServiceImpl.loginServer(GreetingServiceImpl.java:39)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:569)
... 21 more

Caused by: org.hibernate.MappingException: Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister
at org.hibernate.persister.internal.PersisterFactoryImpl.create(PersisterFactoryImpl.java:180)
at org.hibernate.persister.internal.PersisterFactoryImpl.createEntityPersister(PersisterFactoryImpl.java:131)
at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:345)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1737)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1775)
at de.marcelstuht.nerven2.server.HibernateUtil.buildSessionFactory(HibernateUtil.java:18)
... 29 more

Caused by: org.hibernate.InstantiationException: could not instantiate test objectde.marcelstuht.nerven2.shared.model.Account
at org.hibernate.engine.internal.UnsavedValueFactory.instantiate(UnsavedValueFactory.java:49)
at org.hibernate.engine.internal.UnsavedValueFactory.getUnsavedIdentifierValue(UnsavedValueFactory.java:68)
at org.hibernate.tuple.PropertyFactory.buildIdentifierProperty(PropertyFactory.java:75)
at org.hibernate.tuple.entity.EntityMetamodel.<init>(EntityMetamodel.java:143)
at org.hibernate.persister.entity.AbstractEntityPersister.<init>(AbstractEntityPersister.java:498)
at org.hibernate.persister.entity.SingleTableEntityPersister.<init>(SingleTableEntityPersister.java:142)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at org.hibernate.persister.internal.PersisterFactoryImpl.create(PersisterFactoryImpl.java:158)
... 34 more

Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at org.hibernate.engine.internal.UnsavedValueFactory.instantiate(UnsavedValueFactory.java:46)
... 44 more

Caused by: java.lang.NullPointerException
at de.marcelstuht.nerven2.shared.model.Account.<init>(Account.java:52)
... 49 more

帐户.java

package de.marcelstuht.nerven2.shared.model;

import java.io.Serializable;
import java.util.List;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.validation.constraints.NotNull;

import org.apache.commons.codec.digest.DigestUtils;
import org.hibernate.Session;
import org.hibernate.criterion.*;

import de.marcelstuht.nerven2.server.HibernateUtil;

@Entity
@Table(name = "account")
public class Account implements Serializable {

private static final long serialVersionUID = 2675108132819989138L;

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "id")
Long id;

@NotNull
    @Column(name = "username", unique = true)
String username;

@Column(name = "password")
String password;

@Column(name = "email")
String email;

protected Session session;


public Account() {
    session = HibernateUtil.getSessionFactory().openSession();
}

public Account(Long id) {
    this.id = id;
    session = HibernateUtil.getSessionFactory().openSession();
}

public Account(Long id, String username, String password, String email) {
    this.id = id;
    this.username = username;
    this.password = password;
    this.email = email;
    session = HibernateUtil.getSessionFactory().openSession();

}

public void setId(Long newid) {
    id = newid;
}

public Long getId() {
    return id;
}

public void setUsername(String user) {
    username = user;
}

public String getUsername() {
    return username;
}

public void setEmail(String mail) {
    email = mail;
}

public String getEmail() {
    return email;
}

public void setPassword(String newPass) {
    password = newPass;
}

public void setNewPassword(String newPass) {
    password = hashPassword(newPass);
}

public boolean checkPassword(String pass) {
    pass = hashPassword(pass);
    if (password.equals(pass)) return true;
    else return false;
}

private String hashPassword(String password) {
    return DigestUtils.shaHex("wudu390909dfh"+password);
}

public Account get(Long id) {
    session.beginTransaction();
    Account result = (Account) session.get("account", id);
    session.getTransaction().commit();
    return result;
}

public Long saveOrUpdate(Account account) {
    if (account == null) {
        return null;
    }

    session.beginTransaction();

    session.saveOrUpdate(account);
    Long id = (Long) session.getIdentifier(account);

    session.getTransaction().commit();
    return id;
}

public void delete(Account account) {
    if (account == null) {
        return;
    }
    session.beginTransaction();
    session.delete(account);
    session.getTransaction().commit();
}

public List<Account> getAccountByUsername(String user) {
    session.beginTransaction();

    @SuppressWarnings("unchecked")
    List<Account> result = session
            .createCriteria(Account.class)
            .add(Restrictions.eq("username", user))
            .list();
    session.getTransaction().commit();

    return result;
}

}

HibernateUtil.java

package de.marcelstuht.nerven2.server;

import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.jboss.logging.Logger;

public class HibernateUtil {
private static final SessionFactory sessionFactory = buildSessionFactory();

protected HibernateUtil() {

}

private static SessionFactory buildSessionFactory() {
    try {
        // Create the SessionFactory from hibernate.cfg.xml
        Configuration cfg = new Configuration();
        SessionFactory sf = cfg.configure().buildSessionFactory();
        return sf;
    } catch (Exception ex) {
        // Make sure you log the exception, as it might be swallowed
        Logger.getLogger(HibernateUtil.class).error("Initial SessionFactory creation failed.", ex);
        throw new ExceptionInInitializerError(ex);
    }
}

public static SessionFactory getSessionFactory() {
    return sessionFactory;
}
}

hibernate.cfg.xml

<!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">com.mysql.jdbc.Driver</property>
    <property name="connection.url">jdbc:mysql://127.0.0.1:3306/ba</property>
    <property name="connection.username">*myuser*</property>
    <property name="connection.password">*mypassword*</property>

    <!-- JDBC connection pool (use the built-in) -->
    <property name="connection.pool_size">1</property>

    <!-- SQL dialect -->
    <property name="dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property>

    <!-- Disable the second-level cache  -->
    <!-- <property name="cache.provider_class">org.hibernate.cache.internal.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="hibernate.bytecode.provider">javassist</property>

    <!-- Names the annotated entity class -->
    <mapping class="de.marcelstuht.nerven2.shared.model.Account"/>

</session-factory>

我尝试了 Hibernate 3.6.9 和 4.0.1(在不同的 Eclipse 项目中)。Skitch 上提供了我添加到项目中的 JAR 的屏幕截图:https://skitch.com/marcelstuht/g7h8h/properties-for-nerven2

Answer 1

引发者:java.lang.NullPointerException在 de.marcelstuht.nerven2.shared.model.Account.(Account.java:52)... 49 更多

从 Account 的构造函数中删除任何内容。你有一个循环依赖。 Hibernate 使用公共(public)的无参数构造函数来处理它的 beans

1. HibernateUtil 加载
2. 这会强制静态运行 buildSessionFactory
3. Hibernate 通过无参数实例化 Account
4. 这又调用 HibernateUtil......

相信我:除了 POJO setter 之外，没有任何代码的公共(public)无参数构造函数。没有别的了。