com.kurento.kmf.content.jsonrpc.GsonUtils.java Source code

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Here is the source code for com.kurento.kmf.content.jsonrpc.GsonUtils.java

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/*
 * (C) Copyright 2013 Kurento (http://kurento.org/)
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the GNU Lesser General Public License
 * (LGPL) version 2.1 which accompanies this distribution, and is available at
 * http://www.gnu.org/licenses/lgpl-2.1.html
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 */
package com.kurento.kmf.content.jsonrpc;

import java.lang.reflect.Type;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
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 com.kurento.kmf.content.jsonrpc.param.JsonRpcRequestParams;
import com.kurento.kmf.content.jsonrpc.result.JsonRpcResponseResult;

/**
 * 
 * Gson/JSON utilities; used to serialize Java object to JSON (as String).
 * 
 * @author Miguel Pars (mparisdiaz@gsyc.es)
 * @version 1.0.0
 */
public class GsonUtils {

    /**
     * Static instance of Gson object.
     */
    private static Gson gson;

    /**
     * Serialize Java object to JSON (as String).
     * 
     * @param obj
     *            Java Object representing a JSON message to be serialized
     * @return Serialized JSON message (as String)
     */
    public static String toString(Object obj) {
        return GsonUtils.getGson().toJson(obj);
    }

    /**
     * Gson object accessor (getter).
     * 
     * @return son object
     */
    public static Gson getGson() {
        if (gson != null) {
            return gson;
        }

        GsonBuilder builder = new GsonBuilder();
        builder.registerTypeAdapter(JsonRpcRequest.class, new JsonRpcRequestDeserializer());

        builder.registerTypeAdapter(JsonRpcResponse.class, new JsonRpcResponseDeserializer());

        gson = builder.create();

        return gson;
    }

    static boolean isIn(JsonObject jObject, String[] clues) {
        for (String clue : clues) {
            if (jObject.has(clue)) {
                return true;
            }
        }
        return false;
    }
}

class JsonRpcResponseDeserializer implements JsonDeserializer<JsonRpcResponse> {

    @Override
    public JsonRpcResponse deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)
            throws JsonParseException {

        if (!(json instanceof JsonObject)) {
            throw new JsonParseException("JonObject expected, found " + json.getClass().getSimpleName());
        }

        JsonObject jObject = (JsonObject) json;

        if (!jObject.has("jsonrpc")) {
            throw new JsonParseException("Invalid JsonRpc response lacking version 'jsonrpc' field");
        }

        if (!jObject.get("jsonrpc").getAsString().equals(JsonRpcConstants.JSON_RPC_VERSION)) {
            throw new JsonParseException("Invalid JsonRpc version");
        }

        if (!jObject.has("id")) {
            throw new JsonParseException("Invalid JsonRpc response lacking 'id' field");
        }

        if (jObject.has("result")) {
            return new JsonRpcResponse((JsonRpcResponseResult) context
                    .deserialize(jObject.get("result").getAsJsonObject(), JsonRpcResponseResult.class),
                    jObject.get("id").getAsInt());
        } else if (jObject.has("error")) {
            return new JsonRpcResponse((JsonRpcResponseError) context
                    .deserialize(jObject.get("error").getAsJsonObject(), JsonRpcResponseError.class),
                    jObject.get("id").getAsInt());
        } else {
            throw new JsonParseException("Invalid JsonRpc response lacking 'result' and 'error' fields");
        }

    }
}

class JsonRpcRequestDeserializer implements JsonDeserializer<JsonRpcRequest> {

    @Override
    public JsonRpcRequest deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)
            throws JsonParseException {

        if (!(json instanceof JsonObject)) {
            throw new JsonParseException(
                    "Invalid JsonRpc request showning JsonElement type " + json.getClass().getSimpleName());
        }

        JsonObject jObject = (JsonObject) json;

        if (!jObject.has("jsonrpc")) {
            throw new JsonParseException("Invalid JsonRpc request lacking version 'jsonrpc' field");
        }

        if (!jObject.get("jsonrpc").getAsString().equals(JsonRpcConstants.JSON_RPC_VERSION)) {
            throw new JsonParseException("Invalid JsonRpc version");
        }

        if (!jObject.has("method")) {
            throw new JsonParseException("Invalid JsonRpc request lacking 'method' field");
        }

        if (!jObject.has("params")) {
            throw new JsonParseException("Invalid JsonRpc request lacking 'params' field");
        }

        if (!jObject.has("id")) {
            throw new JsonParseException("Invalid JsonRpc request lacking 'id' field");
        }

        return new JsonRpcRequest(
                jObject.get("method").getAsString(), (JsonRpcRequestParams) context
                        .deserialize(jObject.get("params").getAsJsonObject(), JsonRpcRequestParams.class),
                jObject.get("id").getAsInt());

    }

}