CodenvyJsonProvider.java

/*******************************************************************************
 * Copyright (c) 2012-2015 Codenvy, S.A.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *   Codenvy, S.A. - initial API and implementation
 *******************************************************************************/
package org.eclipse.che.api.core.rest;

import org.eclipse.che.dto.server.DtoFactory;
import org.eclipse.che.dto.shared.DTO;

import org.everrest.core.impl.provider.JsonEntityProvider;

import javax.annotation.Nullable;
import javax.inject.Inject;
import javax.inject.Named;
import javax.inject.Singleton;
import javax.ws.rs.Consumes;
import javax.ws.rs.Produces;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.HttpHeaders;
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 java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import java.nio.charset.Charset;
import java.util.LinkedHashSet;
import java.util.Set;

/**
 * Implementation of {@link MessageBodyReader} and {@link MessageBodyWriter} needed for binding JSON content to and from Java Objects.
 *
 * @author andrew00x
 * @see DTO
 * @see DtoFactory
 */
@Singleton
@Provider
@Produces({MediaType.APPLICATION_JSON})
@Consumes({MediaType.APPLICATION_JSON})
public class CodenvyJsonProvider<T> implements MessageBodyReader<T>, MessageBodyWriter<T> {
    private Set<Class> ignoredClasses;
    private final JsonEntityProvider delegate = new JsonEntityProvider<>();

    @Inject
    public CodenvyJsonProvider(@Nullable @Named("codenvy.json.ignored_classes") Set<Class> ignoredClasses) {
        this.ignoredClasses = ignoredClasses == null ? new LinkedHashSet<Class>() : new LinkedHashSet<>(ignoredClasses);
    }

    @SuppressWarnings("unchecked")
    @Override
    public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
        return !ignoredClasses.contains(type) &&
               (type.isAnnotationPresent(DTO.class) || delegate.isWriteable(type, genericType, annotations, mediaType));
    }

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

    @SuppressWarnings("unchecked")
    @Override
    public void writeTo(T t, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType,
                        MultivaluedMap<String, Object> httpHeaders, OutputStream entityStream) throws IOException, WebApplicationException {
        // Add Cache-Control before start write body.
        httpHeaders.putSingle(HttpHeaders.CACHE_CONTROL, "public, no-cache, no-store, no-transform");
        if (type.isAnnotationPresent(DTO.class)) {
            Writer w = new OutputStreamWriter(entityStream, Charset.forName("UTF-8"));
            try {
                w.write(DtoFactory.getInstance().toJson(t));
            } finally {
                w.flush();
            }
        } else {
            delegate.writeTo(t, type, genericType, annotations, mediaType, httpHeaders, entityStream);
        }
    }

    @SuppressWarnings("unchecked")
    @Override
    public boolean isReadable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
        return !ignoredClasses.contains(type) &&
               (type.isAnnotationPresent(DTO.class) || delegate.isReadable(type, genericType, annotations, mediaType));
    }

    @SuppressWarnings("unchecked")
    @Override
    public T readFrom(Class<T> type, Type genericType, Annotation[] annotations, MediaType mediaType,
                      MultivaluedMap<String, String> httpHeaders, InputStream entityStream) throws IOException, WebApplicationException {
        if (type.isAnnotationPresent(DTO.class)) {
            return DtoFactory.getInstance().createDtoFromJson(entityStream, type);
        }
        return (T)delegate.readFrom(type, genericType, annotations, mediaType, httpHeaders, entityStream);
    }

    /**
     * Get Set of classes that we never try to serialize or deserialize. Returned Set is mutable and new classes may be added in ignored
     * Set.
     */
    public Set<Class> getIgnoredClasses() {
        return ignoredClasses;
    }
}