Nsryjdtyk

I am using a Spring framework (Boot+web+jpa) for a REST service and needs to persist an Entity called Sensor. Since I was using Hibernate, I wanted to keep usingEntityManager. From the Spring Data Access document and some of the questions answered in Stackoverflow, I could see that I should configure LocalEntityManagerFactoryBean or LocalContainerEntityManagerFactoryBean.

Now I was able to read persist.xml and persist the entity through dependency injection @PersistenceUnit(unitName="...") EntityManagerFactory in case for LocalContainerEntityManagerFactoryBean. However, Spring keeps throwing an error everytime when I try to persist new Sensor() instance with LocalEntityManagerFactoryBean as shown below.

// LocalEntityManagerFactoryBean

@Bean

public LocalEntityManagerFactoryBean entityManagerFactory() {

    LocalEntityManagerFactoryBean em = new LocalEntityManagerFactoryBean();

    em.setPersistenceUnitName("myunit");

    JpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();

    em.setJpaVendorAdapter(vendorAdapter);

    return em;

}

Persisting (transaction.begin and end are in the caller method):

private Sensor getSensor(SimpleData sd) {

    List<Sensor> sensors = entityManager.createQuery("select s from Sensor s where s.deviceId = :devid", Sensor.class)

                                     .setParameter("devid", sd.getDeviceId())

                                     .getResultList();

    Sensor sensor = null;

    if(sensors.isEmpty()) {

        sensor = new Sensor();

        sensor.setDeviceId(sd.getDeviceId());

        sensor.setName(sd.getName());

        entityManager.persist(sensor); // Throws an exception

        deviceIdMapper.put(sensor.getDeviceId(), sensor.getId());

        logger.trace("Cannot find the sensor in db, adding: "+sensor.getDeviceId());

    } else {

        sensor = sensors.get(0);

        deviceIdMapper.put(sensor.getDeviceId(), sensor.getId());

        logger.trace("Found a sensor from the db: "+sd.getDeviceId());

    }

    deviceIdMapper.putIfAbsent(sensor.getDeviceId(), sensor.getId());

    logger.trace(sensor);

    return sensor;

}

Exception:

javax.persistence.PersistenceException: org.hibernate.property.access.spi.PropertyAccessException: Error accessing field [protected int com.database.Sensor.id] by reflection for persistent property [com.database.Sensor#id] : com.database.Sensor@6de9600a

at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:154)

at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:181)

at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:188)

at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:807)

at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:785)

at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.base/java.lang.reflect.Method.invoke(Method.java:566)

at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:350)

at com.sun.proxy.$Proxy108.persist(Unknown Source)

at com.DataListener.getSensor(DataListener.java:69)

at com.DataListener.lambda$0(DataListener.java:87)

at java.base/java.util.ArrayList.forEach(ArrayList.java:1540)

at com.DataListener.processData(DataListener.java:86)

at com.DataListener.onMessage(DataListener.java:49)

at org.apache.activemq.ActiveMQMessageConsumer.dispatch(ActiveMQMessageConsumer.java:1321)

at org.apache.activemq.ActiveMQSessionExecutor.dispatch(ActiveMQSessionExecutor.java:131)

at org.apache.activemq.ActiveMQSessionExecutor.iterate(ActiveMQSessionExecutor.java:202)

at org.apache.activemq.thread.PooledTaskRunner.runTask(PooledTaskRunner.java:129)

at org.apache.activemq.thread.PooledTaskRunner$1.run(PooledTaskRunner.java:47)

at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)

at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)

at java.base/java.lang.Thread.run(Thread.java:834)

Caused by: org.hibernate.property.access.spi.PropertyAccessException: Error accessing field [protected int com.database.Sensor.id] by reflection for persistent property [com.database.Sensor#id] : com.database.Sensor@6de9600a

at org.hibernate.property.access.spi.GetterFieldImpl.get(GetterFieldImpl.java:75)

at org.hibernate.tuple.entity.AbstractEntityTuplizer.getIdentifier(AbstractEntityTuplizer.java:224)

at org.hibernate.persister.entity.AbstractEntityPersister.getIdentifier(AbstractEntityPersister.java:4931)

at org.hibernate.persister.entity.AbstractEntityPersister.isTransient(AbstractEntityPersister.java:4631)

at org.hibernate.engine.internal.ForeignKeys.isTransient(ForeignKeys.java:226)

at org.hibernate.event.internal.AbstractSaveEventListener.getEntityState(AbstractSaveEventListener.java:540)

at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:102)

at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:62)

at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:800)

... 20 more

Caused by: java.lang.IllegalArgumentException: Can not set int field com.database.Sensor.id to com.database.Sensor

at java.base/jdk.internal.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:167)

at java.base/jdk.internal.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:171)

at java.base/jdk.internal.reflect.UnsafeFieldAccessorImpl.ensureObj(UnsafeFieldAccessorImpl.java:58)

at java.base/jdk.internal.reflect.UnsafeIntegerFieldAccessorImpl.getInt(UnsafeIntegerFieldAccessorImpl.java:56)

at java.base/java.lang.reflect.Field.getInt(Field.java:594)

at org.hibernate.property.access.spi.GetterFieldImpl.get(GetterFieldImpl.java:62)

... 28 more

Sensor class:

@Entity

public class Sensor {



    @Id

    @GeneratedValue(strategy = GenerationType.IDENTITY)

    protected int id;

    protected String deviceId;

    protected String name;



    @OneToMany(mappedBy = "owner", cascade=CascadeType.ALL)

    private List<SimpleData> simpleDevices = new ArrayList<>();



    public String getName() {

        return name;

    }



    public void setName(String name) {

        this.name = name;

    }



    public String getDeviceId() {

        return deviceId;

    }



    public void setDeviceId(String deviceId) {

        this.deviceId = deviceId;

    }





    public int getId() {

        return id;

    }



    public void setId(int id) {

        this.id = id;

    }



    public List<SimpleData> getSimpleDevices() {

        return simpleDevices;

    }



    public void setSimpleDevices(List<SimpleData> simpleDevices) {

        this.simpleDevices = simpleDevices;

    }



}

There are two questions:

1. Why the error?


2. Spring throws an error if I do not provide DataSource for LocalContainerEntityManagerFactoryBean? LocalEntityManagerFactoryBean uses DataSource configs from persistence.xml Why LocalContainerEntityManagerFactoryBean doesn't do the same?:

Edit 1

I think I have found a solution. If I remove spring-boot-devtools from the dependency, it fixes the problem. In fact when I use spring-boot-devtools I could not read Sensor due to some sort of ClassLoader problem. Maybe some sort of a bug?:

java.lang.ClassCastException: class com.database.Sensor cannot be cast to class com.database.Sensor (com.database.Sensor is in unnamed module of loader 'app'; com.database.Sensor is in unnamed module of loader org.springframework.boot.devtools.restart.classloader.RestartClassLoader @6228d409)

Edit 2
Here is SimpleData class

@Entity

public class SimpleData {



    @Id

    @GeneratedValue(strategy = GenerationType.IDENTITY)

    private int id;



    private double value;



    @JsonIgnore

    private Date time;



    @Transient

    private String deviceId;



    @JsonIgnore

    @Transient

    private String name;



    @ManyToOne(fetch=FetchType.LAZY)

    @JoinColumn(name="sensor_id")

    private Sensor owner;



    public double getValue() {

        return value;

    }



    public void setValue(double value) {

        this.value = value;

    }



    public Date getTime() {

        return time;

    }



    public void setTime(Date time) {

        this.time = time;

    }



    public String getName() {

        return name;

    }



    public void setName(String name) {

        this.name = name;

    }



    public String getDeviceId() {

        return deviceId;

    }



    public void setDeviceId(String deviceId) {

        this.deviceId = deviceId;

    }



    public Sensor getOwner() {

        return owner;

    }



    public void setOwner(Sensor owner) {

        this.owner = owner;

    }

}

Edit 3

Okay, I made a small test program that reproduces the problem: https://github.com/hjparker/spring-boot-devtools-issue.

Once the server is up, you can make a GET request to localhost:8080, which will throw an error. Commenting out spring-boot-devtools in build.gradle will solve the problem. I found this is something to do with the restart classloader in spring-dev-tools (https://docs.spring.io/spring-boot/docs/current/reference/html/using-boot-devtools.html), which reloads developing code every time spring is restarted. But I think some part of the file is not reloaded automatically causing the classcastexception, e.g. An entity loaded with CL1 != An entity loaded with CL2. Can someone explain if I am doing something wrong?

Need to update access modifier private instead of protected, seems that Java persistence tries to get id which is not in package neither is called on some subclass.

@Id

@GeneratedValue(strategy = GenerationType.IDENTITY)

private int id;

private String deviceId;

private String name;

Access modifier documentation

It seems some of the deserializers for Entity or Bean classes managed by hibernate/Spring ORM are not reloaded by the spring-boot-devtools restart classloader properly. I had to explicitly include the classes that perform deserialization to the restart classloader by setting the following properties in META-INF/spring-devtools.properties:

restart.include.hibernate=hibernate.*

restart.include.spring-orm=spring-orm.*

Sources:

https://github.com/AxonFramework/AxonFramework/issues/344

https://docs.spring.io/spring-boot/docs/current/reference/html/using-boot-devtools.html#using-boot-devtools-customizing-classload