root/kraken-filter/src/main/java/org/krakenapps/filter/MessageBuilder.java @ 306

/*
 * Copyright 2009 NCHOVY
 * 
 * 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.krakenapps.filter;

import java.util.HashMap;
import java.util.Map;

import org.krakenapps.filter.impl.DefaultMessage;

/**
 * Builds a message of specific message specification. This class is for
 * convenience.
 * 
 * @author xeraph
 * @since 1.0.0
 */
public class MessageBuilder {
        private MessageSpec spec;
        private Map<String, Object> fields;
        private Map<String, Object> headers;

        /**
         * Prepare a builder of specific message specification.
         * 
         * @param spec
         *            the message specification
         */
        public MessageBuilder(MessageSpec spec) {
                this.spec = spec;
                this.fields = new HashMap<String, Object>();
                this.headers = new HashMap<String, Object>();
        }

        /**
         * Copy from the other message
         * 
         * @param message
         *            the source message
         * @return builder for method chaining
         */
        public MessageBuilder setBase(Message message) {
                this.spec = message.getMessageSpec();

                for (String key : message.keySet()) {
                        fields.put(key, message.get(key));
                }

                for (String key : message.headerKeySet()) {
                        headers.put(key, message.getHeader(key));
                }

                return this;
        }

        /**
         * Sets a property
         * 
         * @param key
         *            the name of the property
         * @param value
         *            the value of the property
         * @return builder for method chaining
         */
        public MessageBuilder set(String key, Object value) {
                fields.put(key, value);
                return this;
        }

        /**
         * Sets a header
         * 
         * @param key
         *            the name of the header
         * @param value
         *            the value of the header
         * @return builder for method chaining
         */
        public MessageBuilder setHeader(String key, Object value) {
                headers.put(key, value);
                return this;
        }

        /**
         * Creates a message instance.
         * 
         * @return the immutable message instance.
         */
        public Message build() {
                Message message = new DefaultMessage(spec, fields, headers);
                fields = new HashMap<String, Object>();
                headers = new HashMap<String, Object>();
                return message;
        }
}