au.com.gridstone.rxstore.converters.JacksonConverter.java Source code

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Here is the source code for au.com.gridstone.rxstore.converters.JacksonConverter.java

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/*
 * Copyright (C) GRIDSTONE 2016
 *
 * 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 au.com.gridstone.rxstore.converters;

import au.com.gridstone.rxstore.Converter;
import au.com.gridstone.rxstore.ConverterException;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;
import java.lang.reflect.Type;

/**
 * A {@link Converter} that uses a Jackson {@link ObjectMapper} to get the
 * job done.
 */
public class JacksonConverter implements Converter {
    private final ObjectMapper objectMapper;

    public JacksonConverter() {
        this(new ObjectMapper());
    }

    public JacksonConverter(ObjectMapper objectMapper) {
        this.objectMapper = objectMapper;
    }

    @Override
    public <T> void write(T data, Type type, File file) throws ConverterException {
        try {
            objectMapper.writeValue(file, data);
        } catch (IOException e) {
            throw new ConverterException(e);
        }
    }

    @Override
    public <T> T read(File file, Type type) throws ConverterException {
        JavaType javaType = objectMapper.getTypeFactory().constructType(type);

        try {
            Reader reader = new FileReader(file);
            T value;

            if (!reader.ready()) {
                value = null;
            } else {
                value = objectMapper.readValue(reader, javaType);
            }

            reader.close();
            return value;
        } catch (Exception e) {
            throw new ConverterException(e);
        }
    }
}