使用 EclipseLink JPA 插入空结构

Question

我有一个带有 SDO_GEOMETRY 列的 Oracle table，我正在尝试使用 EclipseLink JPA2 2.6.1 来实现持久性。我的实体 class 将 JTS Geometry 用于几何对象，并且我编写了一个 AttributeConverter 以将 SDO_GEOMETRY 转换为 JTS Geometry。这很好用，我可以从数据库中读取和写入几何图形。我遇到的问题是我无法保留空的 JTS 几何图形。我收到以下错误：

ORA-00932: 数据类型不一致：预期 MDSYS.SDO_GEOMETRY 得到 CHAR

不确定是我做错了什么，还是 EclipseLink 或 Oracle 中存在错误。

persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">

<persistence-unit name="mainPersistence">
    <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
        <class>persistence.v1.dao.jpa2.converters.GeometryConverter</class>

    <class>persistence.v1.dto.AuthorizationDto</class>

    <properties>
        <property name="eclipselink.weaving" value="false"/>
</persistence-unit>

实体class

package persistence.v1.dto;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

import persistence.v1.dao.jpa2.converters.GeometryConverter;

import com.vividsolutions.jts.geom.Geometry;

@Entity
@Table(name="AUTHORIZATION")
public class AuthorizationDto {

private String authorizationGuid;
private Geometry authorizationGeometry;

public AuthorizationDto() {
}

@Id
@GeneratedValue(strategy = GenerationType.AUTO, generator = "system-uuid")
@Column(name="AUTHORIZATION_GUID", nullable=false)
public String getAuthorizationGuid() {
    return this.authorizationGuid;
}

public void setAuthorizationGuid(String authorizationGuid) {
    this.authorizationGuid = authorizationGuid;
}


@javax.persistence.Convert(converter=GeometryConverter.class)
@Column(name="AUTHORIZATION_GEOMETRY")
public Geometry getAuthorizationGeometry() {
    return this.authorizationGeometry;
}

public void setAuthorizationGeometry(Geometry authorizationGeometry) {
    this.authorizationGeometry = authorizationGeometry;
}
}

几何转换器class

package persistence.v1.dao.jpa2.converters;

import java.sql.SQLException;
import java.sql.Struct;

import javax.persistence.AttributeConverter;
import javax.persistence.Converter;

import oracle.jdbc.OracleConnection;
import oracle.sql.STRUCT;
import oracle.sql.StructDescriptor;

import com.vividsolutions.jts.geom.Geometry;
import com.vividsolutions.jts.io.oracle.OraReader;
import com.vividsolutions.jts.io.oracle.OraWriter;

@Converter(autoApply = true)
public class GeometryConverter implements AttributeConverter<Geometry, Object> {

private static ThreadLocal<OracleConnection> currentConnection = new ThreadLocal<>();

public static void setConnection(OracleConnection connection) {
    currentConnection.set(connection);
}

private Geometry toGeometry(Object geometryData) {
    Geometry result = null;

    OraReader reader = new OraReader();

    try {
        StructDescriptor descriptor = new StructDescriptor(
                "MDSYS.SDO_GEOMETRY", currentConnection.get());
        STRUCT geometryStruct = new STRUCT(descriptor,
                currentConnection.get(), (Object[]) geometryData);

        result = reader.read(geometryStruct);
    } catch (SQLException e) {
        logger.warn("Cound not create geometry from database column", e);
        throw new RuntimeException(e);
    }

    return result;
}

private Struct fromGeometry(Geometry geometry) {
    try {
        return new OraWriter().write(geometry, currentConnection.get());
    } catch (SQLException e) {
        logger.warn("Cound not create database column from geometry "
                + geometry.toText(), e);
        throw new RuntimeException(e);
    }
}

@Override
public Object convertToDatabaseColumn(Geometry geometry) {
    logger.debug("<convertToDatabaseColumn");
    Object result = null;

    if(geometry!=null) {
        result = fromGeometry(geometry);
    }

    logger.debug(">convertToDatabaseColumn "+result);
    return result;
}

@Override
public Geometry convertToEntityAttribute(Object geometryData) {
    logger.debug("<convertToEntityAttribute");
    Geometry result = null;

    if(geometryData!=null) {
        result = toGeometry(geometryData);
    }

    logger.debug(">convertToEntityAttribute "+result);
    return result;
}
}

谢谢

Answer 1

异常是由 EclipseLink 使用 VARCHAR 作为未知类型的默认值引起的。奇怪的是，AttibuteConverter.convertToEntityAttribute 方法接收一个 Object 数组而不是 SDO_GEOMETRY 类型的 Struct，但期望一个 Struct 被 AttibuteConverter.convertToDatabaseColumn 方法 returned。这可能是潜在问题的症状。可能有一种方法可以告诉 EclipseLink 使用注释或其他配置的类型是什么，但我无法发现这是我的解决方法。

我创建了一个 EclipseLink SessionEventListener，它使用登录前方法来识别 return 几何类型的实体方法。我使用 DatabaseField 对象创建一个新的 ObjectRelationalDatabaseField，然后将 sqlType 属性设置为 Struct，并将 sqlTypeName 属性设置为 "MDSYS.SDO_GEOMETRY"。然后我用新的 ObjectRelationalDatabaseField 对象更新映射。 EclipseLink 代码现在有足够的信息来正确设置 Statement.setNull (String parameterName, int sqlType, String typeName) 方法。

在persistence.xml中配置了SessionEventListener，现在空插入成功了。

GeometryInitializerSessionEventListener class

package persistence.v1.dao.jpa2.listeners;

import java.lang.reflect.Method;
import java.sql.Types;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Vector;

import org.eclipse.persistence.descriptors.ClassDescriptor;
import org.eclipse.persistence.internal.descriptors.MethodAttributeAccessor;
import org.eclipse.persistence.mappings.DatabaseMapping;
import org.eclipse.persistence.mappings.DirectToFieldMapping;
import org.eclipse.persistence.mappings.structures.ObjectRelationalDatabaseField;
import org.eclipse.persistence.sessions.Session;
import org.eclipse.persistence.sessions.SessionEvent;
import org.eclipse.persistence.sessions.SessionEventListener;

import com.vividsolutions.jts.geom.Geometry;

public class GeometryInitializerSessionEventListener implements SessionEventListener {

// Omitting empty interface methods

@Override
public void preLogin(SessionEvent event) {

    Session s = event.getSession();

    @SuppressWarnings("rawtypes")
    Map<Class, ClassDescriptor> descriptorMap = s.getDescriptors();

    for (@SuppressWarnings("rawtypes") Entry<Class, ClassDescriptor> entry : descriptorMap.entrySet()) {
        Class<?> cls = entry.getKey();
        ClassDescriptor desc = entry.getValue();

        Vector<DatabaseMapping> mappings = desc.getMappings();
        for(DatabaseMapping mapping:mappings) {

            if (mapping.getAttributeAccessor() instanceof MethodAttributeAccessor) {
                MethodAttributeAccessor maa = (MethodAttributeAccessor) mapping.getAttributeAccessor();

                String methodName = maa.getGetMethodName();

                Method method;
                try {
                    method = cls.getMethod(methodName, new Class[]{});
                } catch (NoSuchMethodException e) {
                    throw new RuntimeException(e);
                } catch (SecurityException e) {
                    throw new RuntimeException(e);
                }

                Class<?> returnType = method.getReturnType();

                if(Geometry.class.equals(returnType)) {

                    DirectToFieldMapping directToFieldMapping = (DirectToFieldMapping) mapping;

                    ObjectRelationalDatabaseField objectRelationalDatabaseField = new ObjectRelationalDatabaseField(mapping.getField());
                    objectRelationalDatabaseField.setSqlType(Types.STRUCT);
                    objectRelationalDatabaseField.setSqlTypeName("MDSYS.SDO_GEOMETRY");
                    directToFieldMapping.setField(objectRelationalDatabaseField);
                }
            }
        }
    }
}
}

Persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0"
xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">

<persistence-unit name="mainPersistence">
    <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider
    <class>persistence.v1.dao.jpa2.converters.GeometryConverter</class>

    <class>persistence.v1.dto.AuthorizationDto</class>

    <properties>
        <property name="eclipselink.weaving" value="false"/>

        <property name="eclipselink.session-event-listener"  value="persistence.v1.dao.jpa2.listeners.GeometryInitializerSessionEventListener"/>
    </properties>
</persistence-unit>

Answer 2

以上答案在使用方法注释时是正确的。使用字段注释时，使用以下 GeometryInitializerSessionEventListener 实现：

package persistence.dao.jpa2.listeners;

import java.lang.reflect.Field;
import java.sql.Types;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Vector;

import org.eclipse.persistence.descriptors.ClassDescriptor;
import org.eclipse.persistence.internal.descriptors.InstanceVariableAttributeAccessor;
import org.eclipse.persistence.mappings.DatabaseMapping;
import org.eclipse.persistence.mappings.DirectToFieldMapping;
import org.eclipse.persistence.mappings.structures.ObjectRelationalDatabaseField;
import org.eclipse.persistence.sessions.Session;
import org.eclipse.persistence.sessions.SessionEvent;
import org.eclipse.persistence.sessions.SessionEventListener;

import com.vividsolutions.jts.geom.Geometry;

public class GeometryInitializerSessionEventListener implements SessionEventListener
{
    @Override
    public void preLogin(SessionEvent event)
    {
        Session s = event.getSession();

        @SuppressWarnings("rawtypes")
        Map<Class, ClassDescriptor> descriptorMap = s.getDescriptors();

        for (@SuppressWarnings("rawtypes")
        Entry<Class, ClassDescriptor> entry: descriptorMap.entrySet())
        {
            ClassDescriptor desc = entry.getValue();
            Vector<DatabaseMapping> mappings = desc.getMappings();
            for (DatabaseMapping mapping: mappings)
            {
                if (mapping.getAttributeAccessor() instanceof InstanceVariableAttributeAccessor)
                {
                    InstanceVariableAttributeAccessor ivaa = (InstanceVariableAttributeAccessor)mapping.getAttributeAccessor();

                    try
                    {
                        Field field = getFieldInHierarchy(desc.getJavaClass(), ivaa.getAttributeName());
                        if (Geometry.class.equals(field.getType()))
                        {
                            DirectToFieldMapping directToFieldMapping = (DirectToFieldMapping)mapping;

                            ObjectRelationalDatabaseField objectRelationalDatabaseField = new ObjectRelationalDatabaseField(mapping.getField());
                            objectRelationalDatabaseField.setSqlType(Types.STRUCT);
                            objectRelationalDatabaseField.setSqlTypeName("MDSYS.SDO_GEOMETRY");
                            directToFieldMapping.setField(objectRelationalDatabaseField);
                        }
                    }
                    catch (IllegalArgumentException e)
                    {
                        throw new IllegalStateException(e);
                    }
                }
            }
        }
    }

    private static Field getFieldInHierarchy(Class<?> clazz, String fieldName)
    {
        for (Class<?> c = clazz; c != null; c = c.getSuperclass())
        {
            try
            {
                return c.getDeclaredField(fieldName);
            }
            catch (final NoSuchFieldException e)
            {
                // continue, trying parent
            }
            catch (Exception e)
            {
                throw new IllegalArgumentException("Cannot access field " + clazz.getName() + "." + fieldName, e);
            }
        }

        throw new IllegalArgumentException("Cannot find field " + clazz.getName() + "." + fieldName);
    }
}

使用 EclipseLink JPA 插入空结构

Insert Null Struct using EclipseLink JPA

java

oracle

jpa

eclipselink

persistence.xml