javax.persistence.PersistenceException:org.hibernate.PersistentObjectException:hibernate中传递给persistent的分离实体

日志：

CategoryTestCase.java

javax.persistence.PersistenceException: org.hibernate.PersistentObjectException: detached entity passed to persist: com.kzn.shoppingbackend.dto.Category
    at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:147)
    at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:155)
    at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:162)
    at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:780)
    at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:758)
    at com.kzn.shoppingbackend.daoImpl.CategoryDAOImpl.update(CategoryDAOImpl.java:51)
    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:497)
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:333)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:190)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
    at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:282)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213)
    at com.sun.proxy.$Proxy29.update(Unknown Source)
    at com.kzn.shoppingbackend.test.CategoryTestCase.updateCategory(CategoryTestCase.java:61)
    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:497)
    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.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    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)
Caused by: org.hibernate.PersistentObjectException: detached entity passed to persist: com.kzn.shoppingbackend.dto.Category
    at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:124)
    at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:58)
    at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:773)
    ... 40 more

CategoryDaoImpl.java

public class CategoryTestCase {
    private static AnnotationConfigApplicationContext context;
    private static CategoryDAO categoryDAO;
    private Category category;

    @BeforeClass
    public static void init() {
        context = new AnnotationConfigApplicationContext();
        context.scan("com.kzn.shoppingbackend");
        context.refresh();
        categoryDAO = (CategoryDAO)context.getBean("categoryDAO");
    }
    @Test
    public void updateCategory() {
        category = categoryDAO.get(2);
        category.setName("Lenovo");

        assertEquals("Successfully added a category inside the table!",true,categoryDAO.update(category));
    }
}

尝试更新传递给持久化的分离实体时，出现错误 请帮忙解决这个问题。为什么它不能保存为更新的值，而每件事情似乎都很完美？为什么无法更新数据库并导致分离错误？您必须使用

sessionFactory.getCurrentSession（）.update（类别）

更新不是一个持久化

@Repository("categoryDAO")
@Transactional
public class CategoryDAOImpl implements CategoryDAO {

    @Autowired
    private SessionFactory sessionFactory;
    /**
     * Method updating single Category
     * @return true if successful
     */
    @Override
    public boolean update(Category category) {
        try {
            sessionFactory.getCurrentSession().persist(category);
            return true;
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }
}