ps：43行對(duì)應(yīng)24行
錯(cuò)誤：
java.lang.NullPointerException
	at?StudentsTest.testSaveStudents(StudentsTest.java:43)
	at?sun.reflect.NativeMethodAccessorImpl.invoke0(Native?Method)
	at?sun.reflect.NativeMethodAccessorImpl.invoke(Unknown?Source)
	at?sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown?Source)
	at?java.lang.reflect.Method.invoke(Unknown?Source)
	at?junit.framework.TestCase.runTest(TestCase.java:168)
	at?junit.framework.TestCase.runBare(TestCase.java:134)
	at?junit.framework.TestResult$1.protect(TestResult.java:110)
	at?junit.framework.TestResult.runProtected(TestResult.java:128)
	at?junit.framework.TestResult.run(TestResult.java:113)
	at?junit.framework.TestCase.run(TestCase.java:124)
	at?junit.framework.TestSuite.runTest(TestSuite.java:243)
	at?junit.framework.TestSuite.run(TestSuite.java:238)
	at?org.junit.internal.runners.JUnit38ClassRunner.run(JUnit38ClassRunner.java:83)
	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:675)
	at?org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
	at?org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)

@Before
	public?void?init(){
		Configuration?config=new?Configuration().configure();
		
		ServiceRegistry?serviceRegisty=new?StandardServiceRegistryBuilder()
				.applySettings(config.getProperties()).build();
		
		sessionFactory=new?MetadataSources(serviceRegisty).buildMetadata().buildSessionFactory();
		
		session=sessionFactory.openSession();
		transaction=session.beginTransaction();
	}
	
	@After
	public?void?destory(){
		transaction.commit();
		session.close();
		sessionFactory.close();
	}
	
	@Test
	public?void?testSaveStudents(){
		Students?s=new?Students(1,"男","張師傅",new?Date(),"武當(dāng)山");
		session.save(s);
	}