org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]
 at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:271)
 at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:233)
 at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:210)
 at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure(JdbcServicesImpl.java:51)
 at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:94)
 at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:242)
 at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:210)
 at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.handleTypes(MetadataBuildingProcess.java:352)
 at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:111)
 at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.build(MetadataBuildingProcess.java:83)
 at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:418)
 at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:87)
 at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:691)
 at StudentsTest.teststudents(StudentsTest.java:25)
 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.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
 at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
 at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
 at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
 at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
 at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
 at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
 at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
 at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
 at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
 at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
 at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
 at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
 at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
 at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
Caused by: org.hibernate.exception.JDBCConnectionException: Error calling Driver#connect
 at org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:115)
 at org.hibernate.engine.jdbc.connections.internal.BasicConnectionCreator$1$1.convert(BasicConnectionCreator.java:101)
 at org.hibernate.engine.jdbc.connections.internal.BasicConnectionCreator.convertSqlException(BasicConnectionCreator.java:123)
 at org.hibernate.engine.jdbc.connections.internal.DriverConnectionCreator.makeConnection(DriverConnectionCreator.java:41)
 at org.hibernate.engine.jdbc.connections.internal.BasicConnectionCreator.createConnection(BasicConnectionCreator.java:58)
 at org.hibernate.engine.jdbc.connections.internal.PooledConnections.addConnections(PooledConnections.java:123)
 at org.hibernate.engine.jdbc.connections.internal.PooledConnections.<init>(PooledConnections.java:42)
 at org.hibernate.engine.jdbc.connections.internal.PooledConnections.<init>(PooledConnections.java:20)
 at org.hibernate.engine.jdbc.connections.internal.PooledConnections$Builder.build(PooledConnections.java:161)
 at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.buildPool(DriverManagerConnectionProviderImpl.java:109)
 at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.configure(DriverManagerConnectionProviderImpl.java:72)
 at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:94)
 at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:242)
 at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:210)
 at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.buildJdbcConnectionAccess(JdbcEnvironmentInitiator.java:145)
 at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:66)
 at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:35)
 at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.initiateService(StandardServiceRegistryImpl.java:88)
 at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:259)
 ... 36 more
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
 at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
 at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
 at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
 at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
 at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
 at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:989)
 at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:341)
 at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2196)
 at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2229)
 at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2024)
 at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:779)
 at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
 at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
 at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
 at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
 at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
 at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
 at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:389)
 at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:330)
 at org.hibernate.engine.jdbc.connections.internal.DriverConnectionCreator.makeConnection(DriverConnectionCreator.java:38)
 ... 51 more
Caused by: java.net.UnknownHostException: hostip
 at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
 at java.net.InetAddress$2.lookupAllHostAddr(InetAddress.java:928)
 at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1323)
 at java.net.InetAddress.getAllByName0(InetAddress.java:1276)
 at java.net.InetAddress.getAllByName(InetAddress.java:1192)
 at java.net.InetAddress.getAllByName(InetAddress.java:1126)
 at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:188)
 at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:300)
 ... 64 more