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问题描述

我在 spring-boot(v2.0.0.RELEASE)中使用 spring-data-jpa ,我只是在MySQL上编写了一个CRUD演示,但在运行时,源代码如下:

I use spring-data-jpa with spring-boot(v2.0.0.RELEASE), I just wrote a CRUD demo on MySQL, but an exception occurs during runtime, source code as follows:

源代码

User.java

@Entity
public class User implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    private Integer id;
    private String username;
    private String password;

    ...getter&setter
}

UserRepository.java

public interface UserRepository extends JpaRepository<User, Integer> {

}

UserServiceTest.java

@RunWith(SpringRunner.class)
@SpringBootTest
public class UserServiceTest {

    @Autowired
    private UserRepository userRepository;

    @Test
    public void getUserById() throws Exception{
        userRepository.getOne(1);
    }

}

application.yml

spring:
  datasource:
    username: ***
    password: ***
    driver-class-name: com.mysql.jdbc.Driver
    url: ********
  thymeleaf:
    cache: false
  jpa:
    show-sql: true
    hibernate:
      ddl-auto: update

异常详细信息

org.hibernate.LazyInitializationException: could not initialize proxy - no Session

at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:155)
at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:268)
at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.invoke(JavassistLazyInitializer.java:73)
at cn.shuaijunlan.sdnsecuritysystem.domain.po.User_$$_jvstc90_0.getUsername(User_$$_jvstc90_0.java)
at cn.shuaijunlan.sdnsecuritysystem.service.UserServiceTest.getUserById(UserServiceTest.java:33)
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)

推荐答案

您可以在测试方法中添加 @Transactional 批注以避免这种异常.

You can add @Transactional annotation to your test method to avoid this exception.

方法 getOne 返回可以延迟加载属性的实体的引用"(代理).看到它代码-它使用 EntityManager getReference 方法.从它javadoc:

Method getOne return the 'reference' (proxy) of the entity which properties can be lazy loaded. See it code - it uses getReference method of EntityManager. From it javadoc:

在Spring中, EntityManager 的实现为 org.hibernate.internal.SessionImpl -因此,如果没有Session,Spring将无法获得此方法.

In Spring the implementation of EntityManager is org.hibernate.internal.SessionImpl - so without the Session the Spring can not get this method.

要进行会话,您只需创建交易...

To have a session you can just create a transaction...

这篇关于LazyInitializationException:无法初始化代理-没有会话的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!

08-04 07:11
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