org.dbrain.data.jackson.JacksonSerializer.java Source code

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Here is the source code for org.dbrain.data.jackson.JacksonSerializer.java

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/*
 * Copyright [2014] [Eric Poitras]
 *
 *     Licensed under the Apache License, Version 2.0 (the "License");
 *     you may not use this file except in compliance with the License.
 *     You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 *     Unless required by applicable law or agreed to in writing, software
 *     distributed under the License is distributed on an "AS IS" BASIS,
 *     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *     See the License for the specific language governing permissions and
 *     limitations under the License.
 */

package org.dbrain.data.jackson;

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonToken;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.Module;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.jsontype.TypeResolverBuilder;
import org.dbrain.data.ObjectConverter;
import org.dbrain.data.TextSerializer;
import org.dbrain.data.jackson.modules.StandardModule;
import org.dbrain.data.text.ParseException;

import java.io.IOException;
import java.io.Reader;
import java.io.Writer;
import java.util.ArrayList;
import java.util.List;
import java.util.function.Consumer;

/**
 * Reader and writer for Value to JSON format.
 */
public class JacksonSerializer implements TextSerializer, ObjectConverter {

    /**
     * @return A new builder with already some good defaults setup.
     */
    public static Builder newBuilder() {
        Builder builder = new Builder();
        builder.withModule(new StandardModule());
        builder.withConfigurator(
                (om) -> om.configure(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT, true));
        return builder;
    }

    /**
     * @return A new builder with no default setup.
     */
    public static Builder newEmptyBuilder() {
        return new Builder();
    }

    private final ObjectMapper objectMapper;

    /**
     * Constructor of the Jackson Serializer from an object mapper.
     */
    public JacksonSerializer(ObjectMapper objectMapper) {
        this.objectMapper = objectMapper;
    }

    /**
     * Check that there is no more token on the wire.
     */
    private void checkEof(JsonParser parser) throws IOException {
        JsonToken token = parser.nextToken();
        if (token != null) {
            throw new ParseException("Unexpected json token: " + token.name());
        }
    }

    /**
     * Read Object from parser.
     */
    public <T> T read(JsonParser r, Class<T> clazz) {
        try {
            return objectMapper.readValue(r, clazz);
        } catch (Exception e) {
            throw new ParseException(e);
        }
    }

    /**
     * Read Json from parser.
     */
    @Override
    public <T> T read(String from, Class<T> clazz) {
        try {
            JsonParser parser = objectMapper.getFactory().createParser(from);
            T value = read(parser, clazz);
            checkEof(parser);
            return value;
        } catch (Exception e) {
            throw new ParseException(e);
        }
    }

    /**
     * Read Json from parser.
     */
    @Override
    public <T> T read(Reader from, Class<T> clazz) {
        try {
            JsonParser parser = objectMapper.getFactory().createParser(from);
            T value = read(parser, clazz);
            checkEof(parser);
            return value;
        } catch (Exception e) {
            throw new ParseException(e);
        }
    }

    @Override
    public void write(Writer to, Object o) {
        try {
            objectMapper.writeValue(to, o);
        } catch (Exception e) {
            throw new IllegalStateException(e);
        }
    }

    @Override
    public String writeToString(Object o) {
        try {
            return objectMapper.writeValueAsString(o);
        } catch (Exception e) {
            throw new IllegalStateException(e);
        }
    }

    /**
     * Convert object to value.
     */
    @Override
    public <T> T convert(Object o, Class<T> clazz) {
        try {
            return objectMapper.convertValue(o, clazz);
        } catch (Exception e) {
            throw new ParseException(e);
        }
    }

    /**
     * Created by epoitras on 10/16/15.
     */
    public static class Builder {

        private final List<Module> modules = new ArrayList<>();
        private final List<Consumer<ObjectMapper>> omConfigs = new ArrayList<>();
        private TypeResolverBuilder<?> typing;

        Builder() {
        }

        public Builder withModule(Module module) {
            if (module != null) {
                modules.add(module);
            }
            return this;
        }

        public Builder withModules(Module... modules) {
            if (modules != null) {
                for (Module m : modules) {
                    withModule(m);
                }
            }
            return this;
        }

        public Builder withConfigurator(Consumer<ObjectMapper> configurator) {
            if (configurator != null) {
                omConfigs.add(configurator);
            }
            return this;
        }

        /**
         * Configure type resolution.
         * @param typing
         * @return
         */
        public Builder withTyping(TypeResolverBuilder<?> typing) {
            this.typing = typing;
            return this;
        }

        public JacksonSerializer build() {
            ObjectMapper om = new ObjectMapper();

            // Register Modules
            om.registerModules(modules);

            // Configure type resolution.
            if (typing != null) {
                om.setDefaultTyping(typing);
            }

            // Customize the Object Mapper
            for (Consumer<ObjectMapper> omConfig : omConfigs) {
                omConfig.accept(om);
            }

            return new JacksonSerializer(om);
        }

    }
}