co.cask.cdap.common.conf.PluginClassDeserializer.java Source code

Introduction

Here is the source code for co.cask.cdap.common.conf.PluginClassDeserializer.java

Source

/*
 * Copyright  2015 Cask Data, 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 co.cask.cdap.common.conf;

import co.cask.cdap.api.annotation.Plugin;
import co.cask.cdap.api.plugin.PluginClass;
import co.cask.cdap.api.plugin.PluginPropertyField;
import com.google.common.collect.ImmutableMap;
import com.google.common.reflect.TypeToken;
import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParseException;

import java.lang.reflect.Type;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

/**
 * A Gson deserializater for creating {@link PluginClass} object from external plugin config file.
 * Used to verify that required fields are present and property map is never null.
 */
public class PluginClassDeserializer implements JsonDeserializer<PluginClass> {

    // Type for the PluginClass.properties map.
    private static final Type PROPERTIES_TYPE = new TypeToken<Map<String, PluginPropertyField>>() {
    }.getType();
    //Type for endpoints property
    private static final Type ENDPOINTS_TYPE = new TypeToken<Set<String>>() {
    }.getType();

    @Override
    public PluginClass deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)
            throws JsonParseException {
        if (!json.isJsonObject()) {
            throw new JsonParseException("PluginClass should be a JSON Object");
        }

        JsonObject jsonObj = json.getAsJsonObject();

        String type = jsonObj.has("type") ? jsonObj.get("type").getAsString() : Plugin.DEFAULT_TYPE;
        String name = getRequired(jsonObj, "name").getAsString();
        String description = jsonObj.has("description") ? jsonObj.get("description").getAsString() : "";
        String className = getRequired(jsonObj, "className").getAsString();

        Set<String> endpointsSet = new HashSet<>();
        if (jsonObj.has("endpoints")) {
            endpointsSet = context.deserialize(jsonObj.get("endpoints"), ENDPOINTS_TYPE);
        }

        Map<String, PluginPropertyField> properties = jsonObj.has("properties")
                ? context.<Map<String, PluginPropertyField>>deserialize(jsonObj.get("properties"), PROPERTIES_TYPE)
                : ImmutableMap.<String, PluginPropertyField>of();

        return new PluginClass(type, name, description, className, null, properties, endpointsSet);
    }

    private JsonElement getRequired(JsonObject jsonObj, String name) {
        if (!jsonObj.has(name)) {
            throw new JsonParseException("Property '" + name + "' is missing from PluginClass.");
        }
        return jsonObj.get(name);
    }
}