org.apache.taverna.configuration.AbstractConfigurable.java Source code

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Here is the source code for org.apache.taverna.configuration.AbstractConfigurable.java

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/**
 * 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.taverna.configuration;

import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.commons.csv.CSVParser;
import org.apache.commons.csv.CSVPrinter;
import org.apache.log4j.Logger;

/**
 * A utility abstract class that simplifies implementing a Configurable.
 * <br>
 * <p>A concrete version of this class needs to define the name,category,
 * UUID string and the set of default values.</p>
 *
 * @author Stuart Owen
 *
 */
public abstract class AbstractConfigurable implements Configurable {

    private Map<String, String> propertyMap = new HashMap<String, String>();

    private static Logger logger = Logger.getLogger(AbstractConfigurable.class);

    public static final String DELETED_VALUE_CODE = "~~DELETED~~";

    private ConfigurationManager configurationManager;

    public Set<String> getKeys() {
        return getInternalPropertyMap().keySet();
    }

    /**
     * Constructs the AbstractConfigurable by either reading from a previously stored set of properties,
     * or by using the default values which results in them being stored for subsequent usage.
     */
    public AbstractConfigurable(ConfigurationManager configurationManager) {
        this.configurationManager = configurationManager;
        try {
            configurationManager.populate(this);
        } catch (Exception e) {
            logger.error("There was an error reading the properties for the Configurable:" + getFilePrefix(), e);
        }
    }

    public synchronized String getProperty(String key) {
        String val = getInternalPropertyMap().get(key);
        if (val == null)
            val = getDefaultProperty(key);
        if (DELETED_VALUE_CODE.equals(val))
            val = null;
        return val;
    }

    public String getDefaultProperty(String key) {
        return getDefaultPropertyMap().get(key);
    }

    protected void store() {
        try {
            configurationManager.store(this);
        } catch (Exception e) {
            logger.error("There was an error storing the new configuration for: " + this.getFilePrefix(), e);
        }
    }

    public void clear() {
        getInternalPropertyMap().clear();
    }

    public synchronized void setProperty(String key, String value) {
        Object oldValue = getInternalPropertyMap().get(key);
        if (value == null) {
            deleteProperty(key);
        } else {
            getInternalPropertyMap().put(key, value);
        }
        if (value == null || !value.equals(oldValue)) {
            store();
        }
    }

    /**
     * Provides access to the internal map.
     * <br>
     * Note that this map will contain entries for deleted values that also have corresponding default values.
     * For this reason using this map directly is discouraged, and  #getProperty(String)} should be used instead.
     * @return
     */
    public Map<String, String> getInternalPropertyMap() {
        return propertyMap;
    }

    public void restoreDefaults() {
        propertyMap.clear();
        propertyMap.putAll(getDefaultPropertyMap());
        store();
    }

    public void deleteProperty(String key) {
        if (getDefaultPropertyMap().containsKey(key)) {
            propertyMap.put(key, DELETED_VALUE_CODE);
        } else {
            propertyMap.remove(key);
        }
    }

    /**
     * Returns an unmodifiable List<String> for the given key. Internally the value is stored as a single String, but converted to a list when calling this method.
     * <br>
     * The list is unmodifiable to prevent the mistake of trying <pre>getPropertyStringList(..).add("new element");</pre> which will not affect the stored
     * list. For the property to be updated this{@link #setPropertyStringList(String, List)} must be used.
     */
    public List<String> getPropertyStringList(String key) {
        String value = getProperty(key);
        if (value != null) {
            return Collections.unmodifiableList(fromListText(value));
        } else {
            return null;
        }
    }

    private List<String> fromListText(String property) {
        List<String> result = new ArrayList<String>();
        if (property.length() > 0) { //an empty string as assumed to be an empty list, rather than a list with 1 empty string in it!
            StringReader reader = new StringReader(property);
            CSVParser csvReader = new CSVParser(reader);
            try {
                for (String v : csvReader.getLine()) {
                    result.add(v);
                }
            } catch (IOException e) {
                logger.error("Exception occurred parsing CSV properties:" + property, e);
            }
        }
        return result;
    }

    /**
     * Set a value that is known to be a list. The value can be retrieved using this{@link #getPropertyStringList(String)}
     * <br>
     * Within the file, the value is stored as a single Comma Separated Value
     */
    public void setPropertyStringList(String key, List<String> value) {
        setProperty(key, toListText(value));
    }

    private String toListText(List<String> values) {
        StringWriter writer = new StringWriter();
        CSVPrinter csvWriter = new CSVPrinter(writer);
        csvWriter.println(values.toArray(new String[] {}));
        return writer.getBuffer().toString().trim();
    }

}