com.novartis.pcs.ontology.rest.servlet.SubtermsServlet.java Source code

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Here is the source code for com.novartis.pcs.ontology.rest.servlet.SubtermsServlet.java

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/* 
    
Copyright 2015 Novartis Institutes for Biomedical Research
    
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.novartis.pcs.ontology.rest.servlet;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.EnumSet;
import java.util.List;

import javax.ejb.EJB;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.lang.StringUtils;

import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.novartis.pcs.ontology.dao.TermDAOLocal;
import com.novartis.pcs.ontology.entity.Term;
import com.novartis.pcs.ontology.entity.VersionedEntity.Status;
import com.novartis.pcs.ontology.rest.json.TermDTO;

/**
 * A simple REST service for subterms. Produces JSON only.
 * 
 * Note: Could use JAX-RS (e.g. RESTEasy or Jersey) but this RESTful
 * service is so trivial that it does not warrant a framework.
 * 
 * @author Carlo Ravagli
 *
 */

@WebServlet("/subterms/*")
@SuppressWarnings("serial")
public class SubtermsServlet extends HttpServlet {
    private static final String MEDIA_TYPE_JSON = "application/json";

    @EJB
    protected TermDAOLocal termDAO;

    private ObjectMapper mapper = new ObjectMapper();

    @Override
    public void init() throws ServletException {
        mapper.enable(SerializationFeature.INDENT_OUTPUT);
        mapper.setSerializationInclusion(JsonInclude.Include.NON_EMPTY);
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String mediaType = getExpectedMediaType(request);
        String pathInfo = StringUtils.trimToNull(request.getPathInfo());
        if (mediaType == null || !MEDIA_TYPE_JSON.equals(mediaType)) {
            response.setStatus(HttpServletResponse.SC_UNSUPPORTED_MEDIA_TYPE);
            response.setContentLength(0);
        } else if (pathInfo == null || pathInfo.length() == 1) {
            response.setStatus(HttpServletResponse.SC_NOT_FOUND);
            response.setContentLength(0);
        } else {
            String referenceId = pathInfo.substring(1);
            boolean pending = Boolean.parseBoolean(request.getParameter("pending"));
            serialize(referenceId, pending, response);
        }
    }

    @Override
    protected void doDelete(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setStatus(HttpServletResponse.SC_METHOD_NOT_ALLOWED);
        resp.setContentLength(0);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setStatus(HttpServletResponse.SC_METHOD_NOT_ALLOWED);
        resp.setContentLength(0);
    }

    @Override
    protected void doPut(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setStatus(HttpServletResponse.SC_METHOD_NOT_ALLOWED);
        resp.setContentLength(0);
    }

    @Override
    protected void doOptions(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String mediaType = getExpectedMediaType(request);

        if (MEDIA_TYPE_JSON.equals(mediaType)) {
            // Preflight CORS support
            response.setStatus(HttpServletResponse.SC_OK);
            response.setHeader("Access-Control-Allow-Origin", "*");
            response.setHeader("Access-Control-Allow-Methods", "GET");
            response.setIntHeader("Access-Control-Max-Age", 60 * 60 * 24);
            response.setContentType(mediaType + ";charset=utf-8");
            response.setContentLength(0);
        } else {
            response.setStatus(HttpServletResponse.SC_UNSUPPORTED_MEDIA_TYPE);
            response.setContentLength(0);
        }
    }

    @Override
    protected long getLastModified(HttpServletRequest req) {
        return System.currentTimeMillis();
    }

    private String getExpectedMediaType(HttpServletRequest request) {
        String mediaType = null;
        String acceptHeader = request.getHeader("Accept");
        if (acceptHeader != null) {
            mediaType = StringUtils
                    .trimToNull(MIMEParse.bestMatch(Collections.singleton(MEDIA_TYPE_JSON), acceptHeader));
        }

        return mediaType;
    }

    private void serialize(String referenceId, boolean pending, HttpServletResponse response) {
        try {
            EnumSet<Status> statusSet = pending ? EnumSet.of(Status.PENDING, Status.APPROVED)
                    : EnumSet.of(Status.APPROVED);
            Collection<Term> terms = termDAO.loadSubTermsByReferenceId(referenceId, statusSet);
            List<TermDTO> dtos = new ArrayList<TermDTO>(terms.size());
            for (Term term : terms) {
                if (statusSet.contains(term.getStatus())) {
                    dtos.add(new TermDTO(term));
                }
            }
            if (!dtos.isEmpty()) {
                response.setStatus(HttpServletResponse.SC_OK);
                response.setHeader("Access-Control-Allow-Origin", "*");
                response.setContentType(MEDIA_TYPE_JSON + ";charset=utf-8");
                response.setHeader("Cache-Control", "public, max-age=0");

                // As per jackson javadocs - Encoding will be UTF-8
                mapper.writeValue(response.getOutputStream(), dtos);
            } else {
                response.setStatus(HttpServletResponse.SC_NOT_FOUND);
                response.setContentLength(0);
            }
        } catch (Exception e) {
            log("Failed to serialize synonyms to JSON", e);
            response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            response.setContentLength(0);
        }
    }
}