Exception in thread “restartedMain” java.lang.reflect.InvocationTargetException Caused by: java.lang.NullPointerException

问题

I am working on SpringBoot, Hibernate application and when I am trying to the run the application. I am getting error "Exception in thread "restartedMain" java.lang.reflect.InvocationTargetException"

Error log that I am getting:

Exception in thread "restartedMain" java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49)
Caused by: java.lang.NullPointerException
    at com.spring.main.SpringLogging3Application.data(SpringLogging3Application.java:97)
    at com.spring.main.SpringLogging3Application.main(SpringLogging3Application.java:53)
    ... 5 more

Below is the source code that I am trying to run. Just assume that I am having two entity classes Question and Answer with it's getter and setter methods.

import java.util.ArrayList;
import java.util.Properties;

import javax.sql.DataSource;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration;
import org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.hibernate5.HibernateTransactionManager;
import org.springframework.orm.hibernate5.LocalSessionFactoryBean;

@SpringBootApplication
@EnableAutoConfiguration(exclude = {DataSourceAutoConfiguration.class,HibernateJpaAutoConfiguration.class,DataSourceTransactionManagerAutoConfiguration.class})
@ComponentScan("com.spring.main")
public class SpringLogging3Application {

    @Autowired
    static SessionFactory factory;

    @Value("${db.driver}")
    private String DB_DRIVER;
    @Value("${db.url}")
    private String DB_URL;
    @Value("${db.username}")
    private String DB_USERNAME;
    @Value("${db.password}")
    private String DB_PASSWORD;
    @Value("${hibarenate.dialect}")
    private String HIBERNATE_DIALECT;
    @Value("${hibarenate.show_sql}")
    private String HIBERNATE_SHOW_SQL;
    @Value("${hibarenate.hbm2ddl.auto}")
    private String HIBERNATE_HBM2DDL_AUTO;
    @Value("${entitymanager.packagesToScan}") 
    private String ENTITYMANAGER_PACKAGES_TOSCAN;


    public static void main(String[] args) {
        SpringApplication.run(SpringLogging3Application.class, args);
        data();
    }
@Autowired  
@Bean(name = "sessionFactory")  
public SessionFactory getSessionFactory(DataSource datasource) throws Exception {

        Properties hibernateproperties = new Properties();


        hibernateproperties.put("hibarenate.dialect", HIBERNATE_DIALECT);
        hibernateproperties.put("hibarenate.show_sql", HIBERNATE_SHOW_SQL);
        hibernateproperties.put("hibarenate.hbm2ddl.auto", HIBERNATE_HBM2DDL_AUTO);

        LocalSessionFactoryBean factorybean = new LocalSessionFactoryBean();
        factorybean.setDataSource(dataSource());
        factorybean.setPackagesToScan(ENTITYMANAGER_PACKAGES_TOSCAN);
        factorybean.setHibernateProperties(hibernateproperties);

        factorybean.afterPropertiesSet();

        SessionFactory sf = factorybean.getObject();
        System.out.println("##getSessionFactory" +sf);
        return sf;
    }
@Autowired
@Bean(name="datasource")
public DataSource dataSource() {    
    DriverManagerDataSource datasources = new DriverManagerDataSource();
    datasources.setDriverClassName(DB_DRIVER);
    datasources.setUrl(DB_URL);
    datasources.setUsername(DB_USERNAME);
    datasources.setPassword(DB_PASSWORD);
     System.out.println("## getDataSource: " +datasources);
    return datasources;
}
@Autowired
@Bean(name="transactrionManager")
public HibernateTransactionManager getTransactionManager(SessionFactory sessionfactory) {
    HibernateTransactionManager manager = new HibernateTransactionManager(sessionfactory);
    //manager.setSessionFactory(sessionFactory().getObject());
    return manager;
}

public static void data() {
    Session session = factory.openSession();
    Transaction t = session.beginTransaction();

    Answer an1=new Answer();  
    an1.setAnswername("Java is programming language");
    an1.setPostedBy("Ravi Malik");  

    Answer an2=new Answer();  
    an2.setAnswername("Java is a platform");  
    an2.setPostedBy("Sudhir Kumar");  

    Question q1=new Question();  
    q1.setQuestion("What is Java?");  
    ArrayList<Answer> l1=new ArrayList<Answer>();  
    l1.add(an1);  
    l1.add(an2);  
    q1.setAnswer(l1);  


      Answer ans3=new Answer();    
        ans3.setAnswername("Servlet is an Interface");    
        ans3.setPostedBy("Jai Kumar");    

        Answer ans4=new Answer();    
        ans4.setAnswername("Servlet is an API");    
        ans4.setPostedBy("Arun");    

    Question q2=new Question();  
    q2.setQuestion("What is Servlet?");  
    ArrayList<Answer> l2=new ArrayList<Answer>();  
    l2.add(ans3);  
    l2.add(ans4);  
    q2.setAnswer(l2);  

    session.persist(q1);    
    session.persist(q2);    

    t.commit();    
    session.close(); 
    System.out.println("Success");
}

}

Updated code - After implementing commandlineRunner

@SpringBootApplication
@EnableAutoConfiguration(exclude = {DataSourceAutoConfiguration.class,HibernateJpaAutoConfiguration.class,DataSourceTransactionManagerAutoConfiguration.class})
@ComponentScan("com.spring.main")
public class SpringLogging3Application implements CommandLineRunner {

    SessionFactory factory;

    @Value("${db.driver}")
    private String DB_DRIVER;
    @Value("${db.url}")
    private String DB_URL;
    @Value("${db.username}")
    private String DB_USERNAME;
    @Value("${db.password}")
    private String DB_PASSWORD;
    @Value("${hibarenate.dialect}")
    private String HIBERNATE_DIALECT;
    @Value("${hibarenate.show_sql}")
    private String HIBERNATE_SHOW_SQL;
    @Value("${hibarenate.hbm2ddl.auto}")
    private String HIBERNATE_HBM2DDL_AUTO;
    @Value("${entitymanager.packagesToScan}") 
    private String ENTITYMANAGER_PACKAGES_TOSCAN;

    @Autowired  
    @Bean(name = "sessionFactory")  
    public SessionFactory getSessionFactory(DataSource datasource) throws Exception {

            Properties hibernateproperties = new Properties();


            hibernateproperties.put("hibarenate.dialect", HIBERNATE_DIALECT);
            hibernateproperties.put("hibarenate.show_sql", HIBERNATE_SHOW_SQL);
            hibernateproperties.put("hibarenate.hbm2ddl.auto", HIBERNATE_HBM2DDL_AUTO);

            LocalSessionFactoryBean factorybean = new LocalSessionFactoryBean();
            factorybean.setDataSource(dataSource());
            factorybean.setPackagesToScan(ENTITYMANAGER_PACKAGES_TOSCAN);
            factorybean.setHibernateProperties(hibernateproperties);

            factorybean.afterPropertiesSet();

            SessionFactory sf = factorybean.getObject();
            System.out.println("##getSessionFactory" +sf);
            return sf;
        }

    @Autowired
    @Bean(name="datasource")
    public DataSource dataSource() {    
        DriverManagerDataSource datasources = new DriverManagerDataSource();
        datasources.setDriverClassName(DB_DRIVER);
        datasources.setUrl(DB_URL);
        datasources.setUsername(DB_USERNAME);
        datasources.setPassword(DB_PASSWORD);
         System.out.println("## getDataSource: " +datasources);
        return datasources;
    }

    @Autowired
    @Bean(name="transactrionManager")
    public HibernateTransactionManager getTransactionManager(SessionFactory sessionfactory) {
        HibernateTransactionManager manager = new HibernateTransactionManager(sessionfactory);
        //manager.setSessionFactory(sessionFactory().getObject());
        return manager;
    }

    public static void main(String[] args) {
        SpringApplication.run(SpringLogging3Application.class, args);

    }

    @Override
    public void run(String... args) throws Exception {
        System.out.println("Inside run method");

        Session session = factory.openSession();
        Transaction t = session.beginTransaction();

        Answer an1=new Answer();  
        an1.setAnswername("Java is programming language");
        an1.setPostedBy("Ravi Malik");  

        Answer an2=new Answer();  
        an2.setAnswername("Java is a platform");  
        an2.setPostedBy("Sudhir Kumar");  

        Question q1=new Question();  
        q1.setQuestion("What is Java?");  
        ArrayList<Answer> l1=new ArrayList<Answer>();  
        l1.add(an1);  
        l1.add(an2);  
        q1.setAnswer(l1);  


          Answer ans3=new Answer();    
          ans3.setAnswername("Servlet is an Interface");    
          ans3.setPostedBy("Jai Kumar");    

          Answer ans4=new Answer();    
          ans4.setAnswername("Servlet is an API");    
          ans4.setPostedBy("Arun");    

        Question q2=new Question();  
        q2.setQuestion("What is Servlet?");  
        ArrayList<Answer> l2=new ArrayList<Answer>();  
        l2.add(ans3);  
        l2.add(ans4);  
        q2.setAnswer(l2);  

        session.persist(q1);    
        session.persist(q2);    

        t.commit();    
        session.close();    
        //return "Success";
    }
}

回答1:

The problem is this.

@Autowired
static SessionFactory factory;

You can not auto wire static fields.

来源：https://stackoverflow.com/questions/62238830/exception-in-thread-restartedmain-java-lang-reflect-invocationtargetexception