proposal/sandbox/input/src/main/org/apache/tools/ant/input/PropertyFileInputHandler.java

/*
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2002 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Ant", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
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 *
 * 5. Products derived from this software may not be called "Apache"
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 *
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 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

package org.apache.tools.ant.input;

import org.apache.tools.ant.BuildException;

import java.io.FileInputStream;
import java.io.IOException;
import java.util.Properties;

/**
 * Reads input from a property file, the file name is read from the
 * system property ant.input.properties, the prompt is the key for input.
 *
 * @author <a href="mailto:stefan.bodewig@epost.de">Stefan Bodewig</a>
 * @version $Revision$
 */
public class PropertyFileInputHandler implements InputHandler {
    private Properties props = null;

    /**
     * Name of the system property we expect to hold the file name.
     */
    public static final String FILE_NAME_KEY = "ant.input.properties";

    /**
     * Empty no-arg constructor.
     */
    public PropertyFileInputHandler() {
    }

    public void handleInput(InputRequest request) throws BuildException {
        readProps();
        Object o = props.get(request.getPrompt());
        if (o == null) {
            throw new BuildException("Unable to find input for "
                                     + request.getPrompt());
        }
        request.setInput(o.toString());
        if (!request.isInputValid()) {
            throw new BuildException("Found invalid input " + o
                                     + " for " + request.getPrompt());
        }
    }

    private synchronized void readProps() throws BuildException {
        if (props == null) {
            String propsFile = System.getProperty(FILE_NAME_KEY);
            if (propsFile == null) {
                throw new BuildException("System property "
                                         + FILE_NAME_KEY
                                         + " for PropertyFileInputHandler not set");
            }
            
            props = new Properties();
            
            try {
                props.load(new FileInputStream(propsFile));
            } catch (IOException e) {
                throw new BuildException("Couldn't load "+propsFile, e);
            }
        }
    }

}