net.jawr.web.resource.bundle.factory.util.JsonPropertiesSource.java Source code

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Here is the source code for net.jawr.web.resource.bundle.factory.util.JsonPropertiesSource.java

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/**
 * Copyright 2014  Ibrahim Chaehoi
 * 
 * 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 net.jawr.web.resource.bundle.factory.util;

import java.io.IOException;
import java.io.InputStream;
import java.util.Iterator;
import java.util.Map.Entry;
import java.util.Properties;

import net.jawr.web.exception.BundlingProcessException;
import net.jawr.web.resource.bundle.IOUtils;

import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;

/**
 * ConfigPropertiesSource implementation that reads its values from a .json
 * file.
 * 
 * This file reads a JSON file and converts it for Jawr in a Properties object.
 * This class allows the user to not use quote for field name even if it's not
 * in the JSON standard. The Array values are converted to String by joining
 * their values and using a comma as a separator.
 * 
 * Here is a sample of JSON configuration :
 * 
 * <pre>
 * {
 *    jawr : { 
 *       debug : {
 *          on : false,
 *          "ie.force.css.bundle" : true
 *          },
 *       "gzip.on" : true,
 *       "charset.name" : "UTF-8",
 *       "use.bundle.mapping" : false,
 *       "factory.use.orphans.mapper" : false,
 *       "strict.mode" : false,
 *       "bundle.hashcode.generator" : "MD5",
 *       custom : {
 *          generators : [ "com.mycomp.generator.ImgGenerator", "com.mycomp.generator.CssGenerator" ],
 *          ...
 * </pre>
 * 
 * @author Ibrahim Chaehoi
 */
public class JsonPropertiesSource extends PropsFilePropertiesSource {

    /** The property field name separator */
    private static final String FIELD_NAME_SEPARATOR = ".";

    /** The array value separator */
    private static final String ARRAY_VALUE_SEPARATOR = ",";

    /**
     * Generates the properties from a JSON node
     * 
     * @param node
     *            the JSON node
     * @param props
     *            the properties to populate
     */
    private void generateProperties(JsonNode node, String parentPrefix, Properties props) {

        Iterator<Entry<String, JsonNode>> fields = node.fields();
        while (fields.hasNext()) {
            Entry<String, JsonNode> entry = fields.next();
            String fieldName = entry.getKey();
            JsonNode jsonNode = entry.getValue();
            String nodePrefix = parentPrefix == null ? fieldName : parentPrefix + FIELD_NAME_SEPARATOR + fieldName;
            if (jsonNode.isTextual() || jsonNode.isBoolean()) {
                props.put(nodePrefix, jsonNode.asText());
            } else if (jsonNode.isNumber()) {
                props.put(nodePrefix, Integer.toString(jsonNode.asInt()));
            } else if (jsonNode.isArray()) {
                String arrayValue = convertToString(jsonNode);
                props.put(nodePrefix, arrayValue);
            }
            generateProperties(jsonNode, nodePrefix, props);
        }
    }

    /* (non-Javadoc)
     * @see net.jawr.web.resource.bundle.factory.util.PropsFilePropertiesSource#loadConfig(java.util.Properties, java.lang.String, java.io.InputStream)
     */
    @Override
    protected void loadConfig(Properties props, String path, InputStream is) {
        try {

            // load properties into a Properties object
            String jsonContent = IOUtils.toString(is);
            // create an ObjectMapper instance.
            ObjectMapper mapper = new ObjectMapper();
            mapper.configure(JsonParser.Feature.ALLOW_UNQUOTED_FIELD_NAMES, true);

            // use the ObjectMapper to read the json string and create a tree
            JsonNode node = mapper.readTree(jsonContent);
            generateProperties(node, null, props);
        } catch (JsonParseException e) {

            throw new BundlingProcessException(
                    "jawr configuration could not be loaded at " + path + FIELD_NAME_SEPARATOR, e);
        } catch (IOException e) {
            throw new BundlingProcessException(
                    "jawr configuration could not be loaded at " + path + FIELD_NAME_SEPARATOR, e);
        }
    }

    /**
     * Converts the json array node to a String
     * 
     * @param jsonArrayNode
     *            the json array node to convert
     * @return a string corresponding to the json array node
     */
    private String convertToString(JsonNode jsonArrayNode) {

        StringBuilder strBuilder = new StringBuilder();
        Iterator<JsonNode> nodeIterator = jsonArrayNode.iterator();
        while (nodeIterator.hasNext()) {
            JsonNode jsonNode = (JsonNode) nodeIterator.next();
            strBuilder.append(jsonNode.asText());
            if (nodeIterator.hasNext()) {
                strBuilder.append(ARRAY_VALUE_SEPARATOR);
            }
        }
        return strBuilder.toString();
    }
}