/**
* Copyright (C) 2012 KRM Associates, Inc. healtheme@krminc.com
*
* 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.
*/
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package com.krminc.phr.api.vitals.converter;
import javax.ws.rs.WebApplicationException;
import java.net.HttpURLConnection;
import java.net.URI;
import java.net.URL;
import javax.xml.bind.JAXBContext;
/**
* Utility class for resolving an uri into an entity.
*
* @author cmccall
*/
public class UriResolver {
private static ThreadLocal<UriResolver> instance = new ThreadLocal<UriResolver>() {
protected UriResolver initialValue() {
return new UriResolver();
}
};
private boolean inProgress = false;
private UriResolver() {
}
/**
* Returns an instance of UriResolver.
*
* @return an instance of UriResolver.
*/
public static UriResolver getInstance() {
return instance.get();
}
private static void removeInstance() {
instance.remove();
}
/**
* Returns the entity associated with the given uri.
*
* @param type the converter class used to unmarshal the entity from XML
* @param uri the uri identifying the entity
* @return the entity associated with the given uri
*/
public <T> T resolve(Class<T> type, URI uri) {
if (inProgress) return null;
inProgress = true;
try {
if (uri == null) {
throw new RuntimeException("No uri specified in a reference.");
}
URL url = uri.toURL();
HttpURLConnection conn = (HttpURLConnection)url.openConnection();
conn.setRequestMethod("GET");
if (conn.getResponseCode() == 200) {
JAXBContext context = JAXBContext.newInstance(type);
return (T) context.createUnmarshaller().unmarshal(conn.getInputStream());
} else {
throw new WebApplicationException(new Throwable("Resource for " + uri + " does not exist."), 404);
}
} catch (WebApplicationException ex) {
throw ex;
} catch (Exception ex) {
throw new WebApplicationException(ex);
} finally {
removeInstance();
}
}
}