为什么按照视频填写返回int会报错

@Test
public void testInset() throws Exception {
   SqlSession sqlSession = null;
   try {
       sqlSession = MyBatisUtils.openSession();
       Goods goods = new Goods();
       goods.setTitle("测试标题");
       goods.setSubTitle("测试副标题");
       goods.setOriginalCost(100f);
       goods.setDiscount(0.85f);
       goods.setIsFreeDelivery(1);
       goods.setCurrentPrice(14004f);
       goods.setCategoryId(43);
       GoodsDAO goodsDAO = sqlSession.getMapper(GoodsDAO.class);
       int i= goodsDAO.insert(goods);
       sqlSession.commit();
       System.out.println(goods.getGoodsId());
   } catch (Exception e) {
       if (sqlSession != null) {
       sqlSession.rollback();
       }
       throw e;
   }finally {
       if (sqlSession != null) {
           MyBatisUtils.closeSession(sqlSession);
       }
   }



}

@Select("insert into t_goods(title,sub_title,original_cost,current_price,discount,is_free_delivery,category_id) VALUES(#{title},#{subTitle},#{originalCost},#{currentPrice},#{discount},#{isFreeDelivery},#{categoryId})")
@SelectKey(statement = "select last_insert_id" ,before=false,keyProperty = "goodsId",resultType = Integer.class)
public int insert( Goods goods);

org.apache.ibatis.binding.BindingException: Mapper method 'com.imooc.mybatis.dao.GoodsDAO.insert attempted to return null from a method with a primitive return type (int).

at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:102)

at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:58)

at com.sun.proxy.$Proxy6.insert(Unknown Source)

at com.imooc.mybatis.MyBatisTestor.testInset(MyBatisTestor.java:44)

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:50)

at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)

at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)

at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)

at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)

at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)

at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)

at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)

at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)

at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)

at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)

at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)

at org.junit.runners.ParentRunner.run(ParentRunner.java:363)

at org.junit.runner.JUnitCore.run(JUnitCore.java:137)

at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)

at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)

at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)

at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

Disconnected from the target VM, address: '127.0.0.1:54577', transport: 'socket'

Process finished with exit code -1

然后我把返回值改成Integer就可以运行