de.agilecoders.wicket.util.Json Maven / Gradle / Ivy

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package de.agilecoders.wicket.util;

import com.google.common.base.Strings;
import org.codehaus.jackson.JsonNode;
import org.codehaus.jackson.JsonParser;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.node.ObjectNode;
import org.codehaus.jackson.type.JavaType;

/**
 * Helper functions to handle JsonNode values.
 *
 * @author miha
 */
public final class Json {

    /**
     * Private constructor to prevent instantiation.
     */
    private Json() {
        throw new UnsupportedOperationException();
    }

    /**
     * @return a new {@link ObjectMapper} instance which allows single
     *         quotes and unquoted keys by default
     */
    private static ObjectMapper createObjectMapper() {
        ObjectMapper mapper = new ObjectMapper();
        mapper.configure(JsonParser.Feature.ALLOW_SINGLE_QUOTES, true);
        mapper.configure(JsonParser.Feature.ALLOW_UNQUOTED_FIELD_NAMES, true);

        return mapper;
    }

    /**
     * Convert an object to JsonNode.
     *
     * @param data Value to convert in Json.
     * @return creates a new json object from given data object
     * @throws ParseException to runtime if object can't be parsed
     */
    public static JsonNode toJson(final Object data) {
        if (data == null) {
            return newObject();
        }

        try {
            return createObjectMapper().valueToTree(data);
        } catch (Exception e) {
            throw new ParseException(e);
        }
    }

    /**
     * Convert a JsonNode to a Java value
     *
     * @param json  Json value to convert.
     * @param clazz Expected Java value type.
     * @param    type of return object
     * @return casted value of given json object
     * @throws ParseException to runtime if json node can't be casted to clazz.
     */
    public static  T fromJson(final JsonNode json, final Class clazz) {
        try {
            return createObjectMapper().treeToValue(json, clazz);
        } catch (Exception e) {
            throw new ParseException(e);
        }
    }

    /**
     * Convert a string to a Java value
     *
     * @param json Json value to convert.
     * @param type Expected Java value type.
     * @param   type of return object
     * @return casted value of given json object
     * @throws ParseException to runtime if json node can't be casted to clazz.
     */
    public static  T fromJson(final String json, final JavaType type) {
        try {
            return createObjectMapper().readValue(parse(json), type);
        } catch (Exception e) {
            throw new ParseException(e);
        }
    }

    /**
     * Convert a JsonNode to a Java value
     *
     * @param json  Json value to convert.
     * @param clazz Expected Java value type.
     * @param    type of return object
     * @return casted value of given json object
     */
    public static  T fromJson(final String json, final Class clazz) {
        return fromJson(parse(json), clazz);
    }

    /**
     * Creates a new empty ObjectNode.
     *
     * @return a new empty json object.
     */
    public static ObjectNode newObject() {
        return createObjectMapper().createObjectNode();
    }

    /**
     * Convert a JsonNode to its string representation. If given
     * value is null an empty json object will returned.
     *
     * @param json The json object to stringify
     * @return stringified version of given json object
     */
    public static String stringify(final JsonNode json) {
        return json != null ? json.toString() : "{}";
    }

    /**
     * Convert an object to a json string representation. If given
     * value is null an empty json object will returned.
     *
     * @param data The data object to stringify
     * @return stringified version of given json object
     */
    public static String stringify(final Object data) {
        return stringify(toJson(data));
    }

    /**
     * verifies a valid json string
     *
     * @param json The json string
     * @return true, if string is a valid json string
     */
    public static boolean isValid(final String json) {
        if (Strings.isNullOrEmpty(json)) {
            return false;
        }

        try {
            return parse(json) != null;
        } catch (ParseException e) {
            return false;
        }
    }

    /**
     * Parse a String representing a json, and return it as a JsonNode.
     *
     * @param jsonString string to parse
     * @return parsed json string as json node
     * @throws ParseException to runtime if json string can't be parsed
     */
    public static JsonNode parse(final String jsonString) {
        if (Strings.isNullOrEmpty(jsonString)) {
            return newObject();
        }

        try {
            return createObjectMapper().readValue(jsonString, JsonNode.class);
        } catch (Throwable e) {
            throw new ParseException(String.format("can't parse string [%s]", jsonString), e);
        }
    }

    /**
     * Json parser runtime exception.
     */
    public static final class ParseException extends RuntimeException {

        /**
         * Constructor.
         *
         * @param message   The error message
         * @param throwable The cause
         */
        public ParseException(String message, Throwable throwable) {
            super(message, throwable);
        }

        /**
         * Constructor.
         *
         * @param throwable the cause
         */
        public ParseException(Throwable throwable) {
            super(throwable);
        }
    }
}