Question

这是我第一次尝试使用Eclipse进行Hibernate，以下是我所做的事情：

创建了一个名为Student.java的Java Bean，如下所示：

package com.jwt.hibernate;

public class Student {

private long id;
private String name;
private String degree;
private String roll;
private String phone;

public long getId() {
    return id;
}
public void setId(long id) {
    this.id = id;
}
public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}
public String getDegree() {
    return degree;
}
public void setDegree(String degree) {
    this.degree = degree;
}
public String getRoll() {
    return roll;
}
public void setRoll(String roll) {
    this.roll = roll;
}
public String getPhone() {
    return phone;
}
public void setPhone(String phone) {
    this.phone = phone;
}   

}

创建了一个映射文件 Student.hbm.xml ，如下所示：

<hibernate-mapping>

<class name="com.jwt.hibernate.Student" table="student">

<id column="ID" name="id" type="long" />
<property column="name" name="name" type="string" />
<property column="degree" name="degree" type="string" />
<property column="roll" name="roll" type="string" />
<property column="phone" name="phone" type="string" />

</class>

</hibernate-mapping>

3。创建了hibernate配置文件 hibernate.cfg.xml ，如下所示：

<?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>

<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/hibernatetutorial</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.password">root</property>
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="show_sql">true</property>
<property name="format_sql">true</property>
<property name="hbm2ddl.auto">create </property>

<mapping resource="com/jwt/hibernate/Student.hbm.xml" />

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

创建了类 SimpleTest.java ，如下所示：

package com.jwt.hibernate;

 import org.hibernate.Session;
 import org.hibernate.SessionFactory;
 import org.hibernate.Transaction;
 import org.hibernate.cfg.Configuration;

 public class SimpleTest {

public static void main(String[] args) {
    Configuration cfg = new Configuration();
    cfg.configure("hibernate.cfg.xml");

    SessionFactory factory = cfg.buildSessionFactory();
    Session session = factory.openSession();

    Student student = new Student();
    student.setName("Mukesh");
    student.setRoll("101");
    student.setPhone("8888");
    student.setDegree("B.E");

    Transaction tx = session.beginTransaction();
    session.save(student);
    System.out.println("Object saved successfully.....!!");
    tx.commit();

    session.close();
    factory.close();
}

}

现在，当我尝试运行SimpleTest时，出现以下错误：

**INFO: HHH000412: Hibernate Core {4.3.7.Final}
Exception in thread "main" java.lang.ExceptionInInitializerError
    at org.hibernate.cfg.Configuration.reset(Configuration.java:326)
    at org.hibernate.cfg.Configuration.<init>(Configuration.java:291)
    at org.hibernate.cfg.Configuration.<init>(Configuration.java:295)
    at com.jwt.hibernate.SimpleTest.main(SimpleTest.java:11)
Caused by: java.lang.NullPointerException
    at org.hibernate.internal.util.ConfigHelper.getResourceAsStream(ConfigHelper.java:170)
    at org.hibernate.cfg.Environment.<clinit>(Environment.java:221)
    ... 4 more**

我仔细检查并确保所有配置和jar文件都已添加到类路径中。所以这不是问题。我真的很感激可能导致这个问题的一些见解，以及如何解决它。

提前致谢！

Answer 1

我建议更新到更高版本的SLF4J 或
您的Hibernate.cfg.xml不在类路径上。它在什么文件夹中？

编辑：

Caused by: java.lang.NullPointerException
at org.hibernate.internal.util.ConfigHelper.getResourceAsStream(ConfigHelper.java:170)

这是您代码中的实际异常，如果您的Hibernate.cfg.xml已加载，请检查SELF4J版本，不要使用user library来获取您的jar文件，将所有库放入您的lib文件夹，然后在类路径中配置它们。

Answer 2

您可能会发现Hibernate的Java配置更加友好。这是我做过的一个例子（注意：在这个类中有像@Autowired和@PostConstruct这样的Spring注释，所以不要混淆）：

public class HibernateConfigBean {

    private static final Logger logger = Logger.getLogger(HibernateConfigBean.class);

    @Autowired private Environment environment;

    private SessionFactory sessionFactory;
    private Configuration configuration;

    @PostConstruct
    private void init(){
        configuration = new Configuration();

        configuration.setProperty("hibernate.dialect", environment.getProperty("hibernate.dialect"));
        configuration.setProperty("hibernate.connection.driver_class", environment.getProperty("hibernate.connection.driver_class"));
        configuration.setProperty("hibernate.connection.url", environment.getProperty("hibernate.connection.url"));
        configuration.setProperty("hibernate.connection.username", environment.getProperty("db_username"));
        configuration.setProperty("hibernate.connection.password", environment.getProperty("db_password"));

        //Add additional Annotated Classes here
        configuration.addAnnotatedClass(UserEntity.class);

        StandardServiceRegistryBuilder builder = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties());
        sessionFactory = configuration.buildSessionFactory(builder.build());
    }

    public SessionFactory getSessionFactory(){
        return sessionFactory;
    }

    //This should be visible outside of the package as it's only used by the GenerateDbSchema class
    void generateSchema() throws Exception {
        try{
            new SchemaExport(configuration).create(false, true);
        } catch (RuntimeException re){
            throw new Exception(re);
        }
    }
}

然后我将我的值放入属性文件中： - ）

Hibernate上的NullPointerException new Configuration（）;

2 个答案: