/**
* Copyright 2010 CosmoCode GmbH
*
* 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 de.cosmocode.palava.ipc.json;
import java.io.OutputStream;
import javax.annotation.concurrent.ThreadSafe;
import org.codehaus.jackson.map.ObjectMapper;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBufferOutputStream;
import org.jboss.netty.buffer.ChannelBuffers;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelHandler.Sharable;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.handler.codec.oneone.OneToOneEncoder;
import com.google.common.base.Preconditions;
import com.google.inject.Inject;
import com.google.inject.name.Named;
/**
* Encodes objects into json {@link ChannelBuffer}.
*
* @since 1.0
* @author Willi Schoenborn
*/
@Sharable
@ThreadSafe
public final class JsonEncoder extends OneToOneEncoder {
/**
* Defaults to the same value as {@link ChannelBuffers#dynamicBuffer()}.
*/
private int estimatedResponseLength = 256;
private final ObjectMapper mapper;
@Inject
public JsonEncoder(ObjectMapper mapper) {
this.mapper = Preconditions.checkNotNull(mapper, "Mapper");
}
@Inject(optional = true)
void setEstimatedResponseLength(@Named(JsonConfig.ESITMATED_RESPONSE_LENGTH) int estimatedResponseLength) {
this.estimatedResponseLength = estimatedResponseLength;
}
@Override
protected Object encode(ChannelHandlerContext ctx, Channel channel, Object message) throws Exception {
final ChannelBuffer buffer = ChannelBuffers.dynamicBuffer(estimatedResponseLength);
final OutputStream stream = new ChannelBufferOutputStream(buffer);
mapper.writeValue(stream, message);
return buffer;
}
}