com.github.dpsm.android.print.gson.GsonResultOperator.java Source code

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Here is the source code for com.github.dpsm.android.print.gson.GsonResultOperator.java

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/*
 * Copyright (C) 2014 David Marques.
 *
 * 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.github.dpsm.android.print.gson;

import com.github.dpsm.android.print.gson.model.GsonModel;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.stream.JsonReader;

import org.json.JSONObject;

import java.io.IOException;
import java.io.InputStreamReader;
import java.lang.reflect.Constructor;
import java.net.HttpURLConnection;

import retrofit.client.Response;
import rx.Observable;
import rx.Subscriber;

/**
 * This Observable.Operator implementation will convert a retrofit.client.Response body into a
 * type T that can be de-serialized through GSON.
 */
public class GsonResultOperator<T extends GsonModel> implements Observable.Operator<T, Response> {

    private static final Gson GSON = new GsonBuilder().create();

    private final Constructor<T> mConstructor;

    private final Class<T> mClass;

    private final Gson mGSON;

    /**
     * Creates an instance of the operator for the specified target class type that uses the
     * specified Gson instance to de-serialize.
     *
     * @param gson  the Gson instance to use for de-serialization.
     * @param clazz the target type to convert to.
     */
    public GsonResultOperator(final Gson gson, final Class<T> clazz) {
        try {
            mConstructor = clazz.getConstructor(JsonObject.class);
        } catch (NoSuchMethodException e) {
            throw new IllegalArgumentException(e);
        }

        mClass = clazz;
        mGSON = gson;
    }

    /**
     * Creates an instance of the operator for the specified target class type.
     *
     * @param clazz the target type to convert to.
     */
    public GsonResultOperator(final Class<T> clazz) {
        this(GSON, clazz);
    }

    @Override
    public Subscriber<? super Response> call(final Subscriber<? super T> subscriber) {
        return new Subscriber<Response>() {
            @Override
            public void onCompleted() {
                subscriber.onCompleted();
            }

            @Override
            public void onError(final Throwable e) {
                subscriber.onError(e);
            }

            @Override
            public void onNext(final Response response) {
                switch (response.getStatus()) {
                case HttpURLConnection.HTTP_OK:
                    InputStreamReader reader = null;
                    try {
                        reader = new InputStreamReader(response.getBody().in());
                        final JsonElement jsonElement = mGSON.fromJson(new JsonReader(reader), JsonObject.class);
                        if (jsonElement != null && jsonElement.isJsonObject()) {
                            final T result = mConstructor.newInstance(jsonElement.getAsJsonObject());
                            subscriber.onNext(result);
                        }
                    } catch (Exception e) {
                        subscriber.onError(e);
                    } finally {
                        if (reader != null) {
                            try {
                                reader.close();
                            } catch (IOException e) {
                                // Nothing to do here
                            }
                        }
                    }
                    break;
                default:
                    subscriber.onError(new IOException("Http Response Failed: " + response.getStatus()));
                    break;
                }
            }
        };
    }
}