src/main/org/apache/tools/ant/taskdefs/optional/EchoProperties.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
 *  permission, please contact apache@apache.org.
 *
 *  5. Products derived from this software may not be called "Apache"
 *  nor may "Apache" appear in their names without prior written
 *  permission of the Apache Group.
 *
 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *  DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 *  ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 *  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 *  USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 *  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.taskdefs.optional;

import org.apache.tools.ant.Project;
import org.apache.tools.ant.Task;
import org.apache.tools.ant.BuildException;

import java.util.Properties;
import java.util.Hashtable;
import java.util.Enumeration;

import java.io.ByteArrayOutputStream;
import java.io.OutputStream;
import java.io.File;
import java.io.IOException;
import java.io.FileOutputStream;

/**
 *  Displays all the current properties in the build. The output can be sent to
 *  a file if desired. <P>
 *
 *  Attribute "destfile" defines a file to send the properties to. This can be
 *  processed as a standard property file later. <P>
 *
 *  Attribute "prefix" defines a prefix which is used to filter the properties
 *  only those properties starting with this prefix will be echoed. <P>
 *
 *  By default, the "failonerror" attribute is enabled. If an error occurs while
 *  writing the properties to a file, and this attribute is enabled, then a
 *  BuildException will be thrown. If disabled, then IO errors will be reported
 *  as a log statement, but no error will be thrown. <P>
 *
 *  Examples: <pre>
 *  &lt;echoproperties  /&gt;
 * </pre> Report the current properties to the log. <P>
 *
 *  <pre>
 *  &lt;echoproperties destfile="my.properties" /&gt;
 * </pre> Report the current properties to the file "my.properties", and will
 *  fail the build if the file could not be created or written to. <P>
 *
 *  <pre>
 *  &lt;echoproperties destfile="my.properties" failonerror="false"
 *      prefix="ant" /&gt;
 * </pre> Report all properties beginning with 'ant' to the file
 *  "my.properties", and will log a message if the file could not be created or
 *  written to, but will still allow the build to continue.
 *
 *@author     Matt Albrecht <a href="mailto:groboclown@users.sourceforge.net">
 *      groboclown@users.sourceforge.net</a>
 *@since      Ant 1.5
 */
public class EchoProperties extends Task {

    /**
     *  File object pointing to the output file. If this is null, then we output
     *  to the project log, not to a file.
     */
    private File destfile = null;

    /**
     *  If this is true, then errors generated during file output will become
     *  build errors, and if false, then such errors will be logged, but not
     *  thrown.
     */
    private boolean failonerror = true;

    /**
     *  prefix string controls which properties to save
     */
    private String prefix = null;


    /**
     * set a file to use for the output
     */
    public void setDestfile(File destfile) {
        this.destfile = destfile;
    }


    /**
     *@param  failonerror  <tt>true</tt> if IO exceptions are reported as build
     *      exceptions, or <tt>false</tt> if IO exceptions are ignored.
     */
    public void setFailOnError(boolean failonerror) {
        this.failonerror = failonerror;
    }


    /**
     *@param  prefix  The new prefix value
     */
    public void setPrefix(String prefix) {
        this.prefix = prefix;
    }


    /**
     *  Run the task.
     *
     *@exception  BuildException  trouble, probably file IO
     */
    public void execute() throws BuildException {
        //copy the properties file
        Hashtable allProps = project.getProperties();

        try {
            if (destfile == null) {
                ByteArrayOutputStream baos = new ByteArrayOutputStream();
                saveProperties(allProps, baos);
                log(baos.toString(), Project.MSG_INFO);
            } else {
                OutputStream os = new FileOutputStream(this.destfile);
                saveProperties(allProps, os);
            }
        } catch (IOException ioe) {
            String message =
                    "Destfile " + destfile + " could not be written to.";
            if (failonerror) {
                throw new BuildException(message, ioe,
                        location);
            } else {
                log(message, Project.MSG_INFO);
            }
        }
    }


    /**
     *  Send the key/value pairs in the hashtable to the given output stream.
     *  The output stream will be closed when this method returns.
     *
     *@param  allProps         propfile to save
     *@param  os               output stream
     *@exception  IOException  trouble
     */
    protected void saveProperties(Hashtable allProps, OutputStream os)
             throws IOException {
        Properties props = new Properties();
        Enumeration enum = allProps.keys();
        while (enum.hasMoreElements()) {
            String name = (String) enum.nextElement();
                String value = (String) allProps.get(name);
            if (prefix == null || name.indexOf(prefix) == 0 ) {
                props.put(name, value);
            }
        }
        try {
            props.save(os, "Ant properties");
        } finally {
            os.close();
        }
    }
}