com.google.publicalerts.cap.CapJsonBuilder.java Source code

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Here is the source code for com.google.publicalerts.cap.CapJsonBuilder.java

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/*
 * Copyright (C) 2011 Google Inc.
 *
 * 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 com.google.publicalerts.cap;

import org.json.JSONException;
import org.json.JSONObject;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

import java.io.IOException;
import java.io.StringWriter;
import java.io.Writer;
import java.util.Map;
import java.util.Set;

/**
 * Writes an Alert to a JSON object.
 * Supports CAP 1.0, 1.1, and 1.2.
 *
 * @author shakusa@google.com (Steve Hakusa)
 */
public class CapJsonBuilder {

    public static final int DEFAULT_INDENT = 2;

    private final int indent;

    public CapJsonBuilder() {
        this(DEFAULT_INDENT);
    }

    public CapJsonBuilder(int indent) {
        this.indent = indent;
    }

    /**
     * Writes the given alert to an JSON string.
     *
     * @param alert the alert to convert
     * @return the alert as an JSON string
     */
    public String toJson(AlertOrBuilder alert) {
        StringWriter writer = new StringWriter();
        try {
            toJson(alert, writer);
        } catch (IOException e) {
            throw new RuntimeException(e);
        } catch (JSONException e) {
            throw new RuntimeException(e);
        }
        return writer.toString();
    }

    /**
     * Writes the given alert to JSON in the given writer.
     *
     * @param alert the alert to convert
     * @param writer the writer to write out the JSON string
     * @throws IOException if there are troubles writing to the writer
     */
    public void toJson(AlertOrBuilder alert, Writer writer) throws JSONException, IOException {
        JSONObject json = toJSONObject(alert);
        if (indent > 0) {
            writer.write(json.toString(indent));
        } else {
            writer.write(json.toString());
        }
    }

    /**
     * Converts the given alert to a JSON object.
     *
     * @param alert the alert to convert
     * @return a JSON object
     * @throws JSONException on conversion error
     */
    public JSONObject toJSONObject(AlertOrBuilder alert) throws JSONException {
        CapXmlBuilder xmlBuilder = new CapXmlBuilder();
        Document document = xmlBuilder.toXmlDocument(alert);
        return documentToJsonObject(document);
    }

    private JSONObject documentToJsonObject(Document document) throws JSONException {
        JSONObject object = new JSONObject();
        Map<String, Set<String>> repeatedFields = CapUtil.getRepeatedFieldNames();
        toJsonObjectInner((Element) document.getElementsByTagName("alert").item(0), object, repeatedFields);
        return object;
    }

    private void toJsonObjectInner(Element element, JSONObject object, Map<String, Set<String>> repeatedFieldsMap)
            throws JSONException {
        NodeList nl = element.getChildNodes();
        Set<String> repeatedFields = repeatedFieldsMap.get(element.getNodeName());
        for (int i = 0; i < nl.getLength(); i++) {
            Element child = (Element) nl.item(i);
            int gcLength = child.getChildNodes().getLength();
            if (gcLength == 0) {
                continue;
            }
            String nodeName = child.getNodeName();
            if (repeatedFields != null && repeatedFields.contains(nodeName)) {
                if (gcLength == 1 && child.getChildNodes().item(0).getNodeType() == Node.TEXT_NODE) {
                    object.append(nodeName, child.getTextContent());
                } else {
                    JSONObject childObj = new JSONObject();
                    toJsonObjectInner(child, childObj, repeatedFieldsMap);
                    object.append(nodeName, childObj);
                }
            } else {
                if (gcLength == 1 && child.getChildNodes().item(0).getNodeType() == Node.TEXT_NODE) {
                    object.put(child.getNodeName(), child.getTextContent());
                } else {
                    JSONObject childObj = new JSONObject();
                    toJsonObjectInner(child, childObj, repeatedFieldsMap);
                    object.put(child.getNodeName(), childObj);
                }
            }
        }
    }
}