junit BeforeClass和AfterClass

import java.util.Date;import java.util.Iterator;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.cfg.AnnotationConfiguration;import org.hibernate.tool.hbm2ddl.SchemaExport;import org.junit.AfterClass;import org.junit.BeforeClass;import org.junit.Test;import com.dada.hibernate.Category;import com.dada.hibernate.Msg;import com.dada.hibernate.Topic;public class HibernateTest {private static SessionFactory sf;@BeforeClasspublic static void beforeClass() {sf = new AnnotationConfiguration().configure().buildSessionFactory();}@AfterClasspublic static void afterClass() {sf.close();}@Testpublic void testSchemaExport() {System.out.println("Hello.");}}