正如其他人提到的，此问题的解决方案是添加@Type(type = "pg-uuid")注释。但是，这种类型与其他供应商的 UUID 类型不兼容，因此这会将您的 Hibernate 类与 Postgres 联系起来。要解决此问题，可以在运行时插入此注释。以下适用于 Hibernate 4.3.7。
首先，您需要插入自定义元数据提供程序来插入注释。创建类的实例后，第一步是这样做Configuration：
// Perform some test to verify that the current database is Postgres.
if (connectionString.startsWith("jdbc:postgresql:")) {
// Replace the metadata provider with our custom metadata provider.
MetadataProviderInjector reflectionManager = MetadataProviderInjector)cfg.getReflectionManager();
reflectionManager.setMetadataProvider(new UUIDTypeInsertingMetadataProvider(reflectionManager.getMetadataProvider()));
}
此自定义元数据提供程序查找类型为 的字段和方法UUID。如果找到，它会插入一个org.hibernate.annotations.Type注释实例，说明类型应该是"pg-uuid"：
package nl.gmt.data;
import org.hibernate.annotations.Parameter;
import org.hibernate.annotations.Type;
import org.hibernate.annotations.common.reflection.AnnotationReader;
import org.hibernate.annotations.common.reflection.MetadataProvider;
import java.lang.annotation.Annotation;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.UUID;
class UUIDTypeInsertingMetadataProvider implements MetadataProvider {
private final Map<AnnotatedElement, AnnotationReader> cache = new HashMap<>();
private final MetadataProvider delegate;
public UUIDTypeInsertingMetadataProvider(MetadataProvider delegate) {
this.delegate = delegate;
}
@Override
public Map<Object, Object> getDefaults() {
return delegate.getDefaults();
}
@Override
public AnnotationReader getAnnotationReader(AnnotatedElement annotatedElement) {
// This method is called a lot of times on the same element, so annotation
// readers are cached. We only cache our readers because the provider
// we delegate to also caches them.
AnnotationReader reader = cache.get(annotatedElement);
if (reader != null) {
return reader;
}
reader = delegate.getAnnotationReader(annotatedElement);
// If this element is a method that returns a UUID, or a field of type UUID,
// wrap the returned reader in a new reader that inserts the "pg-uuid" Type
// annotation.
boolean isUuid = false;
if (annotatedElement instanceof Method) {
isUuid = ((Method)annotatedElement).getReturnType() == UUID.class;
} else if (annotatedElement instanceof Field) {
isUuid = ((Field)annotatedElement).getType() == UUID.class;
}
if (isUuid) {
reader = new UUIDTypeInserter(reader);
cache.put(annotatedElement, reader);
}
return reader;
}
private static class UUIDTypeInserter implements AnnotationReader {
private static final Type INSTANCE = new Type() {
@Override
public Class<? extends Annotation> annotationType() {
return Type.class;
}
@Override
public String type() {
return "pg-uuid";
}
@Override
public Parameter[] parameters() {
return new Parameter[0];
}
};
private final AnnotationReader delegate;
public UUIDTypeInserter(AnnotationReader delegate) {
this.delegate = delegate;
}
@Override
@SuppressWarnings("unchecked")
public <T extends Annotation> T getAnnotation(Class<T> annotationType) {
if (annotationType == Type.class) {
return (T)INSTANCE;
}
return delegate.getAnnotation(annotationType);
}
@Override
public <T extends Annotation> boolean isAnnotationPresent(Class<T> annotationType) {
return annotationType == Type.class || delegate.isAnnotationPresent(annotationType);
}
@Override
public Annotation[] getAnnotations() {
Annotation[] annotations = delegate.getAnnotations();
Annotation[] result = Arrays.copyOf(annotations, annotations.length + 1);
result[result.length - 1] = INSTANCE;
return result;
}
}
}