org.settings4j.util.ELConnectorWrapper.java Source code

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Here is the source code for org.settings4j.util.ELConnectorWrapper.java

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/*
 * #%L
 * settings4j
 * ===============================================================
 * Copyright (C) 2008 - 2016 Brabenetz Harald, Austria
 * ===============================================================
 * 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.
 * #L%
 */
package org.settings4j.util;

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

import org.apache.commons.collections4.Transformer;
import org.apache.commons.collections4.map.LazyMap;
import org.settings4j.Connector;

/**
 * This Wrapper makes the Getter-Methods of Connectors simply accessible by Expressionlanguages like JSP 2.0, Velocity
 * or Freemarker.<br>
 * <br>
 * <B>Example:</B><br>
 * <code>${connectors.string['xyz']}</code> returns the first founded Value in all Connectors:
 * <code>connector.getString("xyz");</code>
 *
 * @author Harald.Brabenetz
 */
public class ELConnectorWrapper {

    private final Connector[] connectors;

    /**
     * The list of all connectors, where Values can be searched.
     *
     * @param connectors a array of Connectors which will be processed in Sequence.
     */
    public ELConnectorWrapper(final Connector... connectors) {
        super();
        this.connectors = connectors;
    }

    /**
     * Usage: <code>${connectors.string['xyz']}</code> returns the first founded Value in all Connectors:
     * <code>connector.getString("xyz");</code>.
     *
     * @return the first founded Value in all connectors
     */
    public Map<String, String> getString() {
        final Transformer<String, String> transformer = new Transformer<String, String>() {

            @Override
            public String transform(final String key) {
                if (key != null) {
                    for (Connector connector : ELConnectorWrapper.this.connectors) {
                        final String result = connector.getString(key);
                        if (result != null) {
                            return result;
                        }
                    }
                }
                return null;
            }
        };
        return LazyMap.lazyMap(new HashMap<String, String>(), transformer);
    }

    /**
     * Usage: <code>${connectors.content['xyz']}</code> returns the first founded Value in all Connectors:
     * <code>connector.getContent("xyz");</code>.
     *
     * @return the first founded Value in all connectors
     */
    public Map<String, byte[]> getContent() {
        final Transformer<String, byte[]> transformer = new Transformer<String, byte[]>() {

            // SuppressWarnings PMD.ReturnEmptyArrayRatherThanNull: returning null for this byte-Arrays is OK.
            @Override
            @SuppressWarnings("PMD.ReturnEmptyArrayRatherThanNull")
            public byte[] transform(final String key) {
                if (key != null) {
                    for (Connector connector : ELConnectorWrapper.this.connectors) {
                        final byte[] result = connector.getContent(key);
                        if (result != null) {
                            return result;
                        }
                    }
                }
                return null;
            }
        };
        return LazyMap.lazyMap(new HashMap<String, byte[]>(), transformer);
    }

    /**
     * Usage: <code>${connectors.object['xyz']}</code> returns the first founded Value in all Connectors:
     * <code>connector.getObject("xyz");</code>.
     *
     * @return the first founded Value in all connectors
     */
    public Map<String, Object> getObject() {
        final Transformer<String, Object> transformer = new Transformer<String, Object>() {

            @Override
            public Object transform(final String key) {
                if (key != null) {
                    for (Connector connector : ELConnectorWrapper.this.connectors) {
                        final Object result = connector.getObject(key);
                        if (result != null) {
                            return result;
                        }
                    }
                }
                return null;
            }
        };
        return LazyMap.lazyMap(new HashMap<String, Object>(), transformer);
    }
}