RepositoryTablesBodyWriter.java

/*
 * Copyright 2012 NGDATA nv
 *
 * 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 org.lilyproject.rest.providers.json;

import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.ext.MessageBodyWriter;
import javax.ws.rs.ext.Provider;
import java.io.IOException;
import java.io.OutputStream;
import java.lang.annotation.Annotation;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.Arrays;
import java.util.Collection;

import org.apache.commons.io.IOUtils;
import org.codehaus.jackson.node.ArrayNode;
import org.codehaus.jackson.node.JsonNodeFactory;
import org.codehaus.jackson.node.ObjectNode;
import org.lilyproject.repository.api.RepositoryTable;
import org.lilyproject.util.json.JsonFormat;

/**
 * MessageBodyWriter for writing Collection<RepositoryTable> instances
 */
@Provider
public class RepositoryTablesBodyWriter implements MessageBodyWriter<Collection<RepositoryTable>> {

    @Override
    public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
        if (Collection.class.isAssignableFrom(type) && mediaType.isCompatible(MediaType.APPLICATION_JSON_TYPE)) {
            if (genericType instanceof ParameterizedType) {
                ParameterizedType parameterizedType = (ParameterizedType)genericType;
                if (Arrays.asList(parameterizedType.getActualTypeArguments()).contains(RepositoryTable.class)) {
                    return true;
                }
            }
        }
        return false;
    }

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

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

        ArrayNode array = JsonNodeFactory.instance.arrayNode();
        for (RepositoryTable table : tables) {
            ObjectNode objectNode = JsonNodeFactory.instance.objectNode();
            objectNode.put("name", table.getName());
            array.add(objectNode);
        }

        IOUtils.write(JsonFormat.serializeAsBytes(array), outputStream);
    }

}