CachingMessageBodyWriter.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you 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.apache.cxf.jaxrs.provider;

import java.io.IOException;
import java.io.OutputStream;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import java.util.Collections;
import java.util.List;

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 org.apache.cxf.jaxrs.utils.ExceptionUtils;

@Provider
public class CachingMessageBodyWriter<T> extends AbstractCachingMessageProvider<T>
    implements MessageBodyWriter<T> {

    private List<MessageBodyWriter<T>> delegatingWriters;

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

    public boolean isWriteable(Class<?> type, Type gType, Annotation[] anns, MediaType mt) {
        if (delegatingWriters != null) {
            return getDelegatingWriter(type, gType, anns, mt) != null;
        } else {
            return isProviderKeyNotSet();
        }
    }

    private MessageBodyWriter<T> getDelegatingWriter(Class<?> type, Type gType, Annotation[] anns, MediaType mt) {
        for (MessageBodyWriter<T> writer: delegatingWriters) {
            if (writer.isWriteable(type, gType, anns, mt)) {
                return writer;
            }
        }
        return null;
    }

    public void writeTo(T obj, Class<?> type, Type gType, Annotation[] anns, MediaType mt,
                        MultivaluedMap<String, Object> theheaders, OutputStream os)
        throws IOException, WebApplicationException {
        this.setObject(obj);
        getWriter(type, gType, anns, mt).writeTo(getObject(), type, gType, anns, mt, theheaders, os);
    }


    protected MessageBodyWriter<T> getWriter(Class<?> type, Type gType, Annotation[] anns, MediaType mt) {
        if (delegatingWriters != null) {
            return getDelegatingWriter(type, gType, anns, mt);
        }
        MessageBodyWriter<T> w = null;

        mc.put(ACTIVE_JAXRS_PROVIDER_KEY, this);
        try {
            @SuppressWarnings("unchecked")
            Class<T> actualType = (Class<T>)type;
            w = mc.getProviders().getMessageBodyWriter(actualType, gType, anns, mt);
        } finally {
            mc.put(ACTIVE_JAXRS_PROVIDER_KEY, null);
        }

        if (w == null) {
            org.apache.cxf.common.i18n.Message message =
                new org.apache.cxf.common.i18n.Message("NO_MSG_WRITER", BUNDLE, type);
            LOG.severe(message.toString());
            throw ExceptionUtils.toInternalServerErrorException(null, null);
        }
        return w;
    }

    public void setDelegatingWriter(MessageBodyWriter<T> writer) {
        this.delegatingWriters = Collections.singletonList(writer);
    }

    public void setDelegatingWriters(List<MessageBodyWriter<T>> writers) {
        this.delegatingWriters = writers;
    }
}