com.google.iosched.model.JsonDataSource.java Source code

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Here is the source code for com.google.iosched.model.JsonDataSource.java

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/*
 * Copyright 2014 Google Inc. All rights reserved.
 *
 * 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.iosched.model;

import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;

import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Iterator;

/**
 * A generic holder for JSON data.
 *
 */
public class JsonDataSource implements Comparable<JsonDataSource>, Iterable<JsonObject> {
    private Enum<?> sourceType;
    private HashMap<String, JsonObject> data;

    public JsonDataSource(Enum<?> sourceType) {
        this.sourceType = sourceType;
        this.data = new HashMap<String, JsonObject>();
    }

    public JsonDataSource(Enum<?> sourceType, JsonArray arr) {
        this(sourceType);
        if (arr != null) {
            addAll(arr);
        }
    }

    public Enum<?> getSourceType() {
        return sourceType;
    }

    public JsonObject getElementById(String id) {
        return data.get(id);
    }

    @Override
    public Iterator<JsonObject> iterator() {
        return data.values().iterator();
    }

    public int size() {
        return data.size();
    }

    public void addElement(String id, JsonObject obj) {
        data.put(id, obj);
    }

    /* (non-Javadoc)
     * @see java.lang.Object#equals(java.lang.Object)
     */
    @Override
    public boolean equals(Object obj) {
        return obj instanceof JsonDataSource && this.sourceType.equals(((JsonDataSource) obj).sourceType);
    }

    /* (non-Javadoc)
     * @see java.lang.Object#hashCode()
     */
    @Override
    public int hashCode() {
        return sourceType.hashCode();
    }

    /* (non-Javadoc)
     * @see java.lang.Comparable#compareTo(java.lang.Object)
     */
    @Override
    public int compareTo(JsonDataSource o) {
        return sourceType.name().compareTo(o.sourceType.name());
    }

    private String getKeyProperty(JsonObject obj) {
        JsonElement idEl = obj.get("id");
        if (idEl == null) {
            // reflection is not efficient in general, but the overhead should be insignificant
            // compared to the usual times taken to load a datasource (either from HTTP, disk or
            // cloud storage)
            Method m;
            try {
                m = sourceType.getClass().getMethod("getKey");
                if (m != null) {
                    return (String) m.invoke(sourceType);
                }
            } catch (Exception e) {
                throw new IllegalArgumentException("Error! Cannot add JsonArray of type " + sourceType.name()
                        + " because there is no property \"id\" in the JsonArray element "
                        + "nor a static getKey() method in the enum.", e);
            }
        }
        return "id";
    }

    public void addAll(JsonArray arr) {
        String idProperty = null;
        for (int i = 0; i < arr.size(); i++) {
            JsonObject obj = arr.get(i).getAsJsonObject();
            if (idProperty == null) {
                idProperty = getKeyProperty(obj);
            }
            String id = obj.get(idProperty).getAsString();
            addElement(id, obj);
        }
    }
}