如何保存点列 postgres - Hibernate

Question

我必须在 postgres 数据库中保存点数据类型。没有与点映射的对象，我尝试过 java.awt.Point，但它给出了异常：

Exception in thread "main" org.hibernate.type.SerializationException: could not deserialize
    at org.hibernate.internal.util.SerializationHelper.doDeserialize(SerializationHelper.java:262)
    at org.hibernate.internal.util.SerializationHelper.deserialize(SerializationHelper.java:306)
    at org.hibernate.type.descriptor.java.SerializableTypeDescriptor.fromBytes(SerializableTypeDescriptor.java:155)
    at org.hibernate.type.descriptor.java.SerializableTypeDescriptor.wrap(SerializableTypeDescriptor.java:130)
    at org.hibernate.type.descriptor.java.SerializableTypeDescriptor.wrap(SerializableTypeDescriptor.java:44)
    at org.hibernate.type.descriptor.sql.VarbinaryTypeDescriptor$2.doExtract(VarbinaryTypeDescriptor.java:71)
    at org.hibernate.type.descriptor.sql.BasicExtractor.extract(BasicExtractor.java:64)
    at org.hibernate.type.AbstractStandardBasicType.nullSafeGet(AbstractStandardBasicType.java:267)
    at org.hibernate.type.AbstractStandardBasicType.nullSafeGet(AbstractStandardBasicType.java:263)
    at org.hibernate.type.AbstractStandardBasicType.nullSafeGet(AbstractStandardBasicType.java:253)
    at org.hibernate.type.AbstractStandardBasicType.hydrate(AbstractStandardBasicType.java:338)
    at org.hibernate.persister.entity.AbstractEntityPersister.hydrate(AbstractEntityPersister.java:2969)
    at org.hibernate.loader.plan.exec.process.internal.EntityReferenceInitializerImpl.loadFromResultSet(EntityReferenceInitializerImpl.java:324)
    at org.hibernate.loader.plan.exec.process.internal.EntityReferenceInitializerImpl.hydrateEntityState(EntityReferenceInitializerImpl.java:251)
    at org.hibernate.loader.plan.exec.process.internal.AbstractRowReader.readRow(AbstractRowReader.java:107)
    at org.hibernate.loader.plan.exec.internal.EntityLoadQueryDetails$EntityLoaderRowReader.readRow(EntityLoadQueryDetails.java:255)
    at org.hibernate.loader.plan.exec.process.internal.ResultSetProcessorImpl.extractResults(ResultSetProcessorImpl.java:129)
    at org.hibernate.loader.plan.exec.internal.AbstractLoadPlanBasedLoader.executeLoad(AbstractLoadPlanBasedLoader.java:138)
    at org.hibernate.loader.plan.exec.internal.AbstractLoadPlanBasedLoader.executeLoad(AbstractLoadPlanBasedLoader.java:102)
    at org.hibernate.loader.entity.plan.AbstractLoadPlanBasedEntityLoader.load(AbstractLoadPlanBasedEntityLoader.java:186)
    at org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:4126)
    at org.hibernate.event.internal.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:503)
    at org.hibernate.event.internal.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:468)
    at org.hibernate.event.internal.DefaultLoadEventListener.load(DefaultLoadEventListener.java:213)
    at org.hibernate.event.internal.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:275)
    at org.hibernate.event.internal.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:151)
    at org.hibernate.internal.SessionImpl.fireLoad(SessionImpl.java:1070)
    at org.hibernate.internal.SessionImpl.access$2000(SessionImpl.java:176)
    at org.hibernate.internal.SessionImpl$IdentifierLoadAccessImpl.load(SessionImpl.java:2551)
    at org.hibernate.internal.SessionImpl.get(SessionImpl.java:955)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.hibernate.context.internal.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:356)
    at com.sun.proxy.$Proxy0.get(Unknown Source)
    at SampleMain.getPoints(SampleMain.java:49)
    at SampleMain.main(SampleMain.java:19)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:140)
Caused by: java.io.StreamCorruptedException: invalid stream header: 2832312E
    at java.io.ObjectInputStream.readStreamHeader(ObjectInputStream.java:804)
    at java.io.ObjectInputStream.<init>(ObjectInputStream.java:299)
    at org.hibernate.internal.util.SerializationHelper$CustomObjectInputStream.<init>(SerializationHelper.java:328)
    at org.hibernate.internal.util.SerializationHelper$CustomObjectInputStream.<init>(SerializationHelper.java:318)
    at org.hibernate.internal.util.SerializationHelper.doDeserialize(SerializationHelper.java:237)
    ... 42 more

而Point实现了Serializable。另外请指导我如何为此列类型编写自定义用户类型。

谢谢。

Answer 1

您应该使用org.postgresql.geometric.PGpoint。

Answer 2

您必须编写自定义序列化和反序列化方法

import java.io.IOException;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializerProvider;
import org.postgresql.geometric.PGpoint;

public class PointToJsonSerializer extends JsonSerializer<PGpoint> {

@Override
public void serialize(PGpoint value, JsonGenerator jgen,
                      SerializerProvider provider) throws IOException,
        JsonProcessingException {
    System.out.println("in serialize");
    String jsonValue = "null";
    try
    {
        if(value != null) {
            double lat = value.x;
            double lon = value.y;
            jsonValue = String.format("POINT (%s %s)", lat, lon);
        }
    }
    catch(Exception e) {}

jgen.writeString(jsonValue);
  }

 }

和反序列化器

import java.io.IOException;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonDeserializer;
import org.postgresql.geometric.PGpoint;


public class JsonToPointDeserializer extends JsonDeserializer<PGpoint> {

    //private final static GeometryFactory geometryFactory = new GeometryFactory(new PrecisionModel(), 26910);

    @Override
    public PGpoint deserialize(JsonParser jp, DeserializationContext ctxt)
            throws IOException, JsonProcessingException {
        System.out.println("in deserialize");
        try {
            String text = jp.getText();
            System.out.println(text);
            if(text == null || text.length() <= 0)
                return null;

            String[] coordinates = text.replaceFirst("POINT ?\\(", "").replaceFirst("\\)", "").split(" ");
            double lat = Double.parseDouble(coordinates[0]);
            double lon = Double.parseDouble(coordinates[1]);

            PGpoint point = new PGpoint(lat, lon);
            return point;
        }
        catch(Exception e){
            return null;
        }
    }

}