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• GraphSON2Mapper.java

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com.datastax.driver.dse.graph.GraphSON2Mapper Maven / Gradle / Ivy

/*
 * Copyright DataStax, Inc.
 *
 * This software can be used solely with DataStax Enterprise. Please consult the license at
 * http://www.datastax.com/terms/datastax-dse-driver-license-terms
 */
package com.datastax.driver.dse.graph;

import com.fasterxml.jackson.annotation.JsonTypeInfo;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.databind.jsontype.TypeResolverBuilder;
import com.fasterxml.jackson.databind.module.SimpleModule;
import com.fasterxml.jackson.databind.ser.DefaultSerializerProvider;
import java.sql.Timestamp;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.List;
import java.util.Map;
import java.util.TimeZone;
import java.util.UUID;

/**
 * An extension to the standard Jackson {@code ObjectMapper} which automatically registers the
 * standard {@link GraphSON2GremlinDriverModule} for serializing Graph elements. This class can be
 * used for generalized JSON serialization tasks that require meeting GraphSON standards.
 */
class GraphSON2Mapper {

  private final List customModules;
  private final boolean loadCustomSerializers;
  private final boolean normalize;
  private final TypeInfo typeInfo;

  private GraphSON2Mapper(final Builder builder) {
    this.customModules = builder.customModules;
    this.loadCustomSerializers = builder.loadCustomModules;
    this.normalize = builder.normalize;
    this.typeInfo = builder.typeInfo;
  }

  ObjectMapper createMapper() {
    final ObjectMapper om = new ObjectMapper();
    om.disable(SerializationFeature.FAIL_ON_EMPTY_BEANS);

    for (SimpleModule module : customModules) {
      om.registerModule(module);
    }

    // plugin external serialization modules
    if (loadCustomSerializers) om.findAndRegisterModules();

    final GraphSONTypeIdResolver graphSONTypeIdResolver = new GraphSONTypeIdResolver();
    final TypeResolverBuilder typer =
        new GraphSONTypeResolverBuilder()
            .typesEmbedding(getTypeInfo())
            .valuePropertyName("@value")
            .init(JsonTypeInfo.Id.CUSTOM, graphSONTypeIdResolver)
            .typeProperty("@type");

    // Registers native Java types that are supported by Jackson
    registerJavaBaseTypes(graphSONTypeIdResolver, om);

    // Register types to typeResolver for the Custom modules
    for (SimpleModule module : customModules) {
      if (module instanceof GraphSON2JacksonModule) {
        final GraphSON2JacksonModule mod = (GraphSON2JacksonModule) module;
        final Map, String> moduleTypeDefinitions = mod.getTypeDefinitions();
        if (moduleTypeDefinitions != null) {
          if (mod.getTypeNamespace() == null || mod.getTypeNamespace().isEmpty())
            throw new IllegalStateException(
                "Cannot specify a module for GraphSON 2.0 with type definitions but without a type Domain. "
                    + "If no specific type domain is required, use Gremlin's default domain, \"g\" but there may be collisions.");

          for (Map.Entry, String> typeDef : moduleTypeDefinitions.entrySet()) {
            graphSONTypeIdResolver.addCustomType(
                String.format("%s:%s", mod.getTypeNamespace(), typeDef.getValue()),
                typeDef.getKey(),
                om);
          }
        }
      }
    }
    om.setDefaultTyping(typer);

    // this provider toStrings all unknown classes and converts keys in Map objects that are Object
    // to String.
    final DefaultSerializerProvider provider = new GraphSONSerializerProvider();
    om.setSerializerProvider(provider);

    if (normalize) om.enable(SerializationFeature.ORDER_MAP_ENTRIES_BY_KEYS);

    // keep streams open to accept multiple values (e.g. multiple vertices)
    om.getFactory().disable(JsonGenerator.Feature.AUTO_CLOSE_TARGET);
    return om;
  }

  static Builder build() {
    return new Builder();
  }

  TypeInfo getTypeInfo() {
    return this.typeInfo;
  }

  private void registerJavaBaseTypes(
      final GraphSONTypeIdResolver graphSONTypeIdResolver, ObjectMapper om) {
    graphSONTypeIdResolver.addCustomType(
        String.format("%s:%s", "g", UUID.class.getSimpleName()), UUID.class, om);
    graphSONTypeIdResolver.addCustomType(
        String.format("%s:%s", "g", Class.class.getSimpleName()), Class.class, om);
    graphSONTypeIdResolver.addCustomType(
        String.format("%s:%s", "g", Calendar.class.getSimpleName()), Calendar.class, om);
    graphSONTypeIdResolver.addCustomType(
        String.format("%s:%s", "g", Date.class.getSimpleName()), Date.class, om);
    graphSONTypeIdResolver.addCustomType(
        String.format("%s:%s", "g", TimeZone.class.getSimpleName()), TimeZone.class, om);
    graphSONTypeIdResolver.addCustomType(
        String.format("%s:%s", "g", Timestamp.class.getSimpleName()), Timestamp.class, om);
  }

  static class Builder {
    private final List customModules = new ArrayList();
    private final boolean loadCustomModules = false;
    private final boolean normalize = false;
    // GraphSON 2.0 should have types activated by default, otherwise use there's no point in using
    // it instead of 1.0.
    private final TypeInfo typeInfo = TypeInfo.PARTIAL_TYPES;

    private Builder() {}

    /** Supply a mapper module for serialization/deserialization. */
    Builder addCustomModule(final SimpleModule custom) {
      this.customModules.add(custom);
      return this;
    }

    GraphSON2Mapper create() {
      return new GraphSON2Mapper(this);
    }
  }
}