org.n52.iceland.util.JSONUtils.java Source code

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Here is the source code for org.n52.iceland.util.JSONUtils.java

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/*
 * Copyright 2015 52North Initiative for Geospatial Open Source
 * Software GmbH
 *
 * 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.n52.iceland.util;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Reader;
import java.io.StringReader;
import java.io.StringWriter;
import java.io.Writer;
import java.net.URL;
import java.util.Collection;
import java.util.Map;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.fasterxml.jackson.core.util.DefaultIndenter;
import com.fasterxml.jackson.core.util.DefaultPrettyPrinter;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.ObjectReader;
import com.fasterxml.jackson.databind.ObjectWriter;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.JsonNodeFactory;
import com.fasterxml.jackson.databind.node.ObjectNode;
import com.google.common.base.Function;
import com.google.common.collect.Collections2;
import com.google.common.collect.Maps;
import com.google.common.io.Closeables;

/**
 * TODO JavaDoc
 *
 * @author <a href="mailto:c.autermann@52north.org">Christian Autermann</a>
 *
 * @since 1.0.0
 */
public class JSONUtils {

    private static final Logger LOGGER = LoggerFactory.getLogger(JSONUtils.class);

    private static final JsonNodeFactory FACTORY = JsonNodeFactory.withExactBigDecimals(false);

    private static final ObjectReader READER;

    private static final ObjectWriter WRITER;

    private static final Function<Object, JsonNode> TO_JSON_STRING = (object) -> {
        if (object == null) {
            return nodeFactory().nullNode();
        } else if (object instanceof JsonNode) {
            return (JsonNode) object;
        } else {
            return nodeFactory().textNode(String.valueOf(object));
        }
    };

    static {
        ObjectMapper mapper = new ObjectMapper().setNodeFactory(FACTORY)
                .enable(DeserializationFeature.USE_BIG_DECIMAL_FOR_FLOATS);
        READER = mapper.reader();
        DefaultPrettyPrinter pp = new DefaultPrettyPrinter();
        pp.indentArraysWith(DefaultIndenter.SYSTEM_LINEFEED_INSTANCE);
        WRITER = mapper.writer(pp);
    }

    protected JSONUtils() {
    }

    public static ObjectReader getReader() {
        return READER;
    }

    public static ObjectWriter getWriter() {
        return WRITER;
    }

    public static JsonNodeFactory nodeFactory() {
        return FACTORY;
    }

    public static String print(JsonNode node) {
        final StringWriter writer = new StringWriter();
        try {
            print(writer, node);
            writer.flush();
        } catch (IOException e) {
            // cannot happen
        } finally {
            try {
                Closeables.close(writer, true);
            } catch (IOException ioe) {
                LOGGER.error("Error while colsing closeable!", ioe);
            }
        }
        return writer.toString();
    }

    public static void print(final Writer writer, final JsonNode node) throws IOException {
        getWriter().writeValue(writer, node);
    }

    public static void print(final OutputStream writer, final JsonNode node) throws IOException {
        getWriter().writeValue(writer, node);
    }

    public static JsonNode loadURL(final URL url) throws IOException {
        return getReader().readTree(url.openStream());
    }

    public static JsonNode loadPath(final String path) throws IOException {
        try (FileInputStream in = new FileInputStream(path)) {
            return getReader().readTree(in);
        }
    }

    public static JsonNode loadFile(final File file) throws IOException {
        try (FileInputStream in = new FileInputStream(file)) {
            return getReader().readTree(in);
        }
    }

    public static JsonNode loadStream(final InputStream in) throws IOException {
        return getReader().readTree(in);
    }

    public static JsonNode loadReader(final Reader reader) throws IOException {
        return getReader().readTree(reader);
    }

    public static JsonNode loadString(final String json) {
        try {
            return loadReader(new StringReader(json));
        } catch (IOException ex) {
            // cannot happen
            throw new RuntimeException(ex);
        }
    }

    public static ObjectNode toJSON(Map<String, ?> map) {
        ObjectNode node = nodeFactory().objectNode();
        if (map != null) {
            node.setAll(Maps.transformValues(map, TO_JSON_STRING));
        }
        return node;
    }

    public static ArrayNode toJSON(Collection<?> coll) {
        ArrayNode node = nodeFactory().arrayNode();
        node.addAll(Collections2.transform(coll, TO_JSON_STRING));
        return node;
    }
}