br.com.infocarwebservice.rest.GsonMessageBodyHandler.java Source code

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Here is the source code for br.com.infocarwebservice.rest.GsonMessageBodyHandler.java

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/*
 * InfoCarWebService 1.0 8 de dez de 2016
 * 
 * Copyright (c) 2016, hyperCLASS. All rights reserved. hyperCLASS
 * proprietary/confidential. Use is subject to license terms.
 */
package br.com.infocarwebservice.rest;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;

import javax.ws.rs.Consumes;
import javax.ws.rs.Produces;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.ext.MessageBodyReader;
import javax.ws.rs.ext.MessageBodyWriter;
import javax.ws.rs.ext.Provider;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

/**
 * A classe <code>GsonMessageBodyHandler</code>  responsvel por prover contedo
 * para a aplicao. Ela consome e retorna JSON em requisies externas.
 *
 * @author Augusto dos Santos
 * @version 1.0 8 de dez de 2016
 */
@Provider
@Produces(MediaType.APPLICATION_JSON + ";charset=utf-8")
@Consumes(MediaType.APPLICATION_JSON + ";charset=utf-8")
public class GsonMessageBodyHandler implements MessageBodyWriter<Object>, MessageBodyReader<Object> {

    private static final String UTF_8 = "UTF-8";
    private Gson gson;

    private Gson getGson() {
        if (gson == null) {
            gson = new GsonBuilder().setPrettyPrinting().create();
        }
        return gson;
    }

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

    @Override
    public Object readFrom(Class<Object> type, Type genericType, Annotation[] annotations, MediaType mediaType,
            MultivaluedMap<String, String> httpHeaders, InputStream entityStream) throws IOException {
        InputStreamReader streamReader = new InputStreamReader(entityStream, UTF_8);
        try {
            Type jsonType;
            if (type.equals(genericType)) {
                jsonType = type;
            } else {
                jsonType = genericType;
            }
            return getGson().fromJson(streamReader, jsonType);
        } finally {
            streamReader.close();
        }
    }

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

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

    @Override
    public void writeTo(Object object, Class<?> type, Type genericType, Annotation[] annotations,
            MediaType mediaType, MultivaluedMap<String, Object> httpHeaders, OutputStream entityStream)
            throws IOException, WebApplicationException {
        OutputStreamWriter writer = new OutputStreamWriter(entityStream, UTF_8);
        try {
            Type jsonType;
            if (type.equals(genericType)) {
                jsonType = type;
            } else {
                jsonType = genericType;
            }
            getGson().toJson(object, jsonType, writer);
        } finally {
            writer.close();
        }
    }
}