ConfigParamsBuilder.java

package ws.antonov.config.api.consumer;

import java.util.LinkedHashMap;
import java.util.Map;

/**
 * Copyright 2011 Alex Antonov
 * 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.
 * 
 * @author aantonov
 * @since 0.1
 */
public final class ConfigParamsBuilder {
    private ConfigParamsMap params = new ConfigParamsMap();

    public ConfigParamsBuilder(){}

    public ConfigParamsBuilder(String key, Object value) {
        params.put(key, value);
    }

    public ConfigParamsBuilder addParam(String key, Object value) {
        params.put(key, value);
        return this;
    }

    public static ConfigParamsBuilder newInstance() {
        return new ConfigParamsBuilder();
    }

    public static ConfigParamsBuilder newInstance(String key, Object value) {
        return new ConfigParamsBuilder(key, value);
    }

    public ConfigParamsMap build() {
        ConfigParamsMap mapToReturn = params;
        mapToReturn.sealMap();
        params = new ConfigParamsMap();
        return mapToReturn;
    }

    public class ConfigParamsMap extends LinkedHashMap<String, Object> {
        private boolean sealed = false;

        void sealMap() {
            sealed = true;
        }

        @Override
        public Object put(String s, Object o) {
            if (!sealed) {
                return super.put(s, o);
            } else {
                throw createException();
            }
        }

        @Override
        public void putAll(Map<? extends String, ? extends Object> map) {
            if (!sealed) {
                super.putAll(map);
            } else {
                throw createException();
            }
        }

        @Override
        protected boolean removeEldestEntry(Map.Entry<String, Object> stringObjectEntry) {
            if (!sealed) {
                return super.removeEldestEntry(stringObjectEntry);
            } else {
                throw createException();
            }
        }

        @Override
        public Object remove(Object o) {
            if (!sealed) {
                return super.remove(o);
            } else {
                throw createException();
            }
        }

        @Override
        public void clear() {
            if (!sealed) {
                super.clear();
            } else {
                throw createException();
            }
        }

        private UnsupportedOperationException createException() {
            return new UnsupportedOperationException("The ConfigParamsMap is sealed and can not be modified");
        }
    }
}