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A very fast POJO codec for MongoDB (used in conjunction with the Mongo Java Driver) that handles generic types as well as polymorphic class hierarchies
package de.bild.codec;
import de.bild.codec.annotations.DecodeUndefinedHandlingStrategy;
import de.bild.codec.annotations.EncodeNullHandlingStrategy;
import org.bson.BsonDocument;
import org.bson.BsonReader;
import org.bson.BsonValue;
import org.bson.BsonWriter;
import org.bson.codecs.Codec;
import org.bson.codecs.CollectibleCodec;
import org.bson.codecs.DecoderContext;
import org.bson.codecs.EncoderContext;
import org.bson.codecs.configuration.CodecProvider;
import org.bson.codecs.configuration.CodecRegistry;
import org.bson.conversions.Bson;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.lang.annotation.Annotation;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.*;
import java.util.function.Predicate;
/**
* Provides a codec for Pojos
* Use the internal builder to register classes and packages that can be handled by the codec
*/
public class PojoCodecProvider implements CodecProvider {
private static final Logger LOGGER = LoggerFactory.getLogger(PojoCodecProvider.class);
private final TypesModel typesModel;
private final PojoContext pojoContext;
PojoCodecProvider(final Set> classes,
final Set packages,
final Set> ignoreAnnotations,
Set> ignoreTypesMatchingClassNamePredicates,
Set> ignoreClasses, List typeCodecProviders,
final List codecResolvers,
CodecConfiguration codecConfiguration, ClassResolver classResolver) {
this.typesModel = new TypesModel(classes, packages, ignoreAnnotations, ignoreTypesMatchingClassNamePredicates, ignoreClasses, classResolver);
this.pojoContext = new PojoContext(typesModel, codecResolvers, typeCodecProviders, codecConfiguration);
}
public static Builder builder() {
return new Builder();
}
@Override
public Codec get(Class clazz, CodecRegistry registry) {
// if clazz has type parameters, we warn the user that generic class definitions are problematic
Codec codec = pojoContext.get(clazz, registry);
if (codec instanceof TypeCodec) {
if (clazz != null && clazz.getTypeParameters().length > 0) {
LOGGER.warn("Generic classes will only be encoded/decoded with their upper bounds! " +
"We could prohibit handling of the pojo codec for those generic classes, " +
"but then user would loose flexibility when subclassing such classes. Class: {}", clazz.toGenericString());
}
TypeCodec typeCodec = (TypeCodec) codec;
// generate dynamic proxy to add CollectibleCodec functionality
if (typeCodec.isCollectible()) {
LOGGER.debug("Enhancing {} to be collectible codec.", typeCodec);
// For easy of use, adding all implemented interfaces to the proxy, so the proxy can be used for most use cases
// Unfortunately the functionalities of the underlying concrete codec class will be missing.
ArrayList> proxyInterfaceList = new ArrayList<>(Arrays.asList(typeCodec.getClass().getInterfaces()));
proxyInterfaceList.add(CollectibleCodec.class);
proxyInterfaceList.add(DelegatingCodec.class); // so users can retrieve the delegating codec form the proxy.
return (CollectibleCodec) Proxy.newProxyInstance(
PojoCodecProvider.class.getClassLoader(),
proxyInterfaceList.toArray(new Class[1]),
new CollectibleCodecDelegator(typeCodec));
}
}
return codec;
}
public Bson getTypeFilter(Class clazz, CodecRegistry registry) {
Codec codec = get(clazz, registry);
if (codec instanceof TypeCodec) {
return ((TypeCodec) codec).getTypeFilter();
}
return null;
}
/**
* delegator for CollectibleCodec
*/
private static class CollectibleCodecDelegator implements InvocationHandler, CollectibleCodec, DelegatingCodec {
private final TypeCodec delegatingCodec;
public CollectibleCodecDelegator(TypeCodec delegatingCodec) {
this.delegatingCodec = delegatingCodec;
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
try {
if (method.getDeclaringClass() == CollectibleCodec.class || method.getDeclaringClass() == DelegatingCodec.class) {
return method.invoke(this, args);
} else {
return method.invoke(delegatingCodec, args);
}
} catch (IllegalAccessException | InvocationTargetException e) {
LOGGER.warn("An exception was caught while invoking the delegate {} with args {}", method, args);
LOGGER.debug("Original exception when invoking target.", e);
// rethrowing cause instead of invocationexception
throw e.getCause();
}
}
@Override
public T generateIdIfAbsentFromDocument(T document) {
return delegatingCodec.generateIdIfAbsentFromDocument(document);
}
@Override
public boolean documentHasId(T document) {
return delegatingCodec.documentHasId(document);
}
@Override
public BsonValue getDocumentId(T document) {
return delegatingCodec.getDocumentId(document);
}
@Override
public T decode(BsonReader reader, DecoderContext decoderContext) {
return delegatingCodec.decode(reader, decoderContext);
}
@Override
public void encode(BsonWriter writer, T value, EncoderContext encoderContext) {
delegatingCodec.encode(writer, value, encoderContext);
}
@Override
public Class getEncoderClass() {
return delegatingCodec.getEncoderClass();
}
@Override
public TypeCodec getDelegate() {
return delegatingCodec;
}
}
/**
*
*/
public static class Builder {
private Set packages = new HashSet<>();
private Set> classes = new HashSet<>();
private List codecResolvers = new ArrayList<>();
private Set> ignoreAnnotations = new HashSet<>();
private Set> ignoreTypesMatchingClassNamePredicates = new HashSet<>();
private Set> ignoreClasses = new HashSet<>();
private ClassResolver classResolver;
private List typeCodecProviders = new ArrayList<>();
private EncodeNullHandlingStrategy.Strategy encodeNullHandlingStrategy = EncodeNullHandlingStrategy.Strategy.CODEC;
private DecodeUndefinedHandlingStrategy.Strategy decodeUndefinedHandlingStrategy = DecodeUndefinedHandlingStrategy.Strategy.KEEP_POJO_DEFAULT;
private boolean encodeNulls = false;
public Builder setPackages(Set packages) {
this.packages = packages;
return this;
}
public Builder register(String... packages) {
this.packages.addAll(Arrays.asList(packages));
return this;
}
public Builder register(Class... classes) {
this.classes.addAll(Arrays.asList(classes));
return this;
}
/**
* If you need to provide a mechanism to scan packages for model classes, register a {@link ClassResolver}
*
* @param classResolver the resolver for classes within packages
* @return this Builder
*/
public Builder registerClassResolver(ClassResolver classResolver) {
this.classResolver = classResolver;
return this;
}
public Builder ignoreTypesAnnotatedWith(Class... annotations) {
this.ignoreAnnotations.addAll(Arrays.asList(annotations));
return this;
}
/**
* If you need to exclude private inner classes form the domain model, use a Predicate
*
* @param ignoreTypesMatchingClassNamePredicates
* @return the Builder
*/
public Builder ignoreTypesMatchingClassNamePredicate(Predicate... ignoreTypesMatchingClassNamePredicates) {
this.ignoreTypesMatchingClassNamePredicates.addAll(Arrays.asList(ignoreTypesMatchingClassNamePredicates));
return this;
}
/**
* If ypu can point to the classes to be ignored, you can do this here
*
* @return the Builder
*/
public Builder ignoreClasses(Class... ignoreClasses) {
this.ignoreClasses.addAll(Arrays.asList(ignoreClasses));
return this;
}
/**
* In case you need to register
*
* @param typeCodecProviders
* @return
*/
public Builder register(TypeCodecProvider... typeCodecProviders) {
this.typeCodecProviders.addAll(Arrays.asList(typeCodecProviders));
return this;
}
public Builder encodeNullHandlingStrategy(EncodeNullHandlingStrategy.Strategy encodeNullHandlingStrategy) {
if (encodeNullHandlingStrategy != null) {
this.encodeNullHandlingStrategy = encodeNullHandlingStrategy;
}
return this;
}
public Builder decodeUndefinedHandlingStrategy(DecodeUndefinedHandlingStrategy.Strategy decodeUndefinedHandlingStrategy) {
if (decodeUndefinedHandlingStrategy != null) {
this.decodeUndefinedHandlingStrategy = decodeUndefinedHandlingStrategy;
}
return this;
}
public Builder encodeNulls(boolean encodeNulls) {
this.encodeNulls = encodeNulls;
return this;
}
/**
* A CodecResolver is supposed to provide specialized codecs in case the default implementation
* {@link BasicReflectionCodec} is not sufficient
*
* @param codecResolvers a list of CodecResolvers to be registered
* @return the builder
*/
public Builder registerCodecResolver(CodecResolver... codecResolvers) {
this.codecResolvers.addAll(Arrays.asList(codecResolvers));
return this;
}
public PojoCodecProvider build() {
CodecConfiguration codecConfiguration = new CodecConfiguration(encodeNulls, encodeNullHandlingStrategy, decodeUndefinedHandlingStrategy);
return new PojoCodecProvider(classes, packages, ignoreAnnotations, ignoreTypesMatchingClassNamePredicates, ignoreClasses, typeCodecProviders, codecResolvers, codecConfiguration, classResolver);
}
}
}