org.metawidget.inspector.json.JsonInspector.java Source code

Introduction

Here is the source code for org.metawidget.inspector.json.JsonInspector.java

Source

// Metawidget
//
// This file is dual licensed under both the LGPL
// (http://www.gnu.org/licenses/lgpl-2.1.html) and the EPL
// (http://www.eclipse.org/org/documents/epl-v10.php). As a
// recipient of Metawidget, you may choose to receive it under either
// the LGPL or the EPL.
//
// Commercial licenses are also available. See http://metawidget.org
// for details.

package org.metawidget.inspector.json;

import static org.metawidget.inspector.InspectionResultConstants.*;

import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Map;

import org.metawidget.inspector.iface.DomInspector;
import org.metawidget.inspector.iface.InspectorException;
import org.metawidget.util.XmlUtils;
import org.w3c.dom.Document;
import org.w3c.dom.Element;

import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;
import com.google.gson.JsonPrimitive;

/**
 * Inspector to look for metadata in JSON files.
 *
 * @author <a href="http://kennardconsulting.com">Richard Kennard</a>
 */

public class JsonInspector implements DomInspector<Element> {

    //
    // Private members
    //

    private JsonObject mRoot;

    //
    // Constructor
    //

    public JsonInspector(JsonInspectorConfig config) {

        InputStream inputStream = config.getInputStream();

        if (inputStream == null) {
            throw InspectorException.newException("No JSON input stream specified");
        }

        // Parse the JSON

        mRoot = (JsonObject) new JsonParser().parse(new InputStreamReader(inputStream));
    }

    //
    // Public methods
    //

    public final String inspect(Object toInspect, String type, String... names) {

        Element element = inspectAsDom(toInspect, type, names);

        if (element == null) {
            return null;
        }

        return XmlUtils.nodeToString(element, false);
    }

    public Element inspectAsDom(Object toInspect, String type, String... names) {

        JsonObject root = getRoot();

        // Traverse names

        for (String name : names) {

            if (!root.has(name)) {
                return null;
            }

            root = root.getAsJsonObject(name);
        }

        // Start the DOM

        Document document = XmlUtils.newDocument();
        Element documentRoot = document.createElementNS(NAMESPACE, ROOT);
        documentRoot.setAttribute(VERSION, "1.0");
        document.appendChild(documentRoot);
        Element entity = document.createElementNS(NAMESPACE, ENTITY);
        entity.setAttribute(TYPE, type);
        documentRoot.appendChild(entity);

        // Write all JSON values into it

        for (Map.Entry<String, JsonElement> entry : root.entrySet()) {

            JsonElement element = entry.getValue();

            // Write the name

            Element child = document.createElementNS(NAMESPACE, PROPERTY);
            child.setAttribute(NAME, entry.getKey());

            // Write the type

            if (element.isJsonPrimitive()) {

                JsonPrimitive primitive = (JsonPrimitive) element;

                if (primitive.isNumber()) {
                    child.setAttribute(TYPE, int.class.getName());
                } else if (primitive.isBoolean()) {
                    child.setAttribute(TYPE, boolean.class.getName());
                } else {
                    child.setAttribute(TYPE, String.class.getName());
                }
            } else if (element.isJsonArray()) {
                child.setAttribute(TYPE, "array");
            } else {
                child.setAttribute(TYPE, Object.class.getName());
            }

            entity.appendChild(child);
        }

        // Return the DOM

        return documentRoot;
    }

    //
    // Protected methods
    //

    protected JsonObject getRoot() {

        return mRoot;
    }
}