io.hawkcd.http.GsonProvider.java Source code

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Here is the source code for io.hawkcd.http.GsonProvider.java

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/*
 * Copyright (C) 2016 R&D Solutions Ltd.
 *
 * 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 io.hawkcd.http;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import io.hawkcd.utilities.deserializers.MaterialDefinitionAdapter;
import io.hawkcd.utilities.deserializers.TaskDefinitionAdapter;
import io.hawkcd.utilities.deserializers.WsContractDeserializer;
import io.hawkcd.model.MaterialDefinition;
import io.hawkcd.model.TaskDefinition;
import io.hawkcd.model.dto.WsContractDto;

import javax.ws.rs.Consumes;
import javax.ws.rs.Produces;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.core.UriInfo;
import javax.ws.rs.ext.MessageBodyReader;
import javax.ws.rs.ext.MessageBodyWriter;
import javax.ws.rs.ext.Provider;
import java.io.*;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;

@Provider
@Produces(MediaType.APPLICATION_JSON)
@Consumes(MediaType.APPLICATION_JSON)
public class GsonProvider<T> implements MessageBodyReader<T>, MessageBodyWriter<T> {

    private static final String PRETTY_PRINT = "pretty-print";

    private final Gson gson;
    private final Gson prettyGson;

    @Context
    private UriInfo ui;

    public GsonProvider() {
        GsonBuilder builder = new GsonBuilder().serializeNulls().enableComplexMapKeySerialization();

        this.gson = builder.registerTypeAdapter(WsContractDto.class, new WsContractDeserializer())
                .registerTypeAdapter(TaskDefinition.class, new TaskDefinitionAdapter())
                .registerTypeAdapter(MaterialDefinition.class, new MaterialDefinitionAdapter()).create();
        this.prettyGson = builder.setPrettyPrinting().create();
    }

    @Override
    public boolean isReadable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
        return true;
    }

    @Override
    public T readFrom(Class<T> type, Type genericType, Annotation[] annotations, MediaType mediaType,
            MultivaluedMap<String, String> httpHeaders, InputStream entityStream)
            throws IOException, WebApplicationException {

        InputStreamReader reader = new InputStreamReader(entityStream, "UTF-8");
        try {
            return gson.fromJson(reader, type);
        } finally {
            reader.close();
        }
    }

    @Override
    public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
        return true;
    }

    @Override
    public long getSize(T t, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
        return -1;
    }

    @Override
    public void writeTo(T t, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType,
            MultivaluedMap<String, Object> httpHeaders, OutputStream entityStream)
            throws IOException, WebApplicationException {

        PrintWriter printWriter = new PrintWriter(entityStream);
        try {
            String json;
            if (ui.getQueryParameters().containsKey(PRETTY_PRINT)) {
                json = prettyGson.toJson(t);
            } else {
                json = gson.toJson(t);
            }
            printWriter.write(json);
            printWriter.flush();
        } finally {
            printWriter.close();
        }
    }
}