Ant example source code file (LoadProperties.java)

This example Ant source code file (LoadProperties.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Ant tags/keywords

buildexception, buildexception, chainreaderhelper, chainreaderhelper, inputstreamreader, io, javaresource, javaresource, path, properties, resource, string, string, unable, util, vector

The LoadProperties.java source code

/*
 *  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.tools.ant.taskdefs;

import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.util.Properties;
import java.util.Vector;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Task;
import org.apache.tools.ant.filters.util.ChainReaderHelper;
import org.apache.tools.ant.types.Path;
import org.apache.tools.ant.types.Reference;
import org.apache.tools.ant.types.Resource;
import org.apache.tools.ant.types.ResourceCollection;
import org.apache.tools.ant.types.FilterChain;
import org.apache.tools.ant.types.resources.FileResource;
import org.apache.tools.ant.types.resources.JavaResource;
import org.apache.tools.ant.util.FileUtils;

/**
 * Load a file's contents as Ant properties.
 *
 * @since Ant 1.5
 * @ant.task category="utility"
 */
public class LoadProperties extends Task {

    /**
     * Source resource.
     */
    private Resource src = null;

    /**
     * Holds filterchains
     */
    private final Vector filterChains = new Vector();

    /**
     * Encoding to use for input; defaults to the platform's default encoding.
     */
    private String encoding = null;

    /**
     * Set the file to load.
     *
     * @param srcFile The new SrcFile value
     */
    public final void setSrcFile(final File srcFile) {
        addConfigured(new FileResource(srcFile));
    }

    /**
     * Set the resource name of a property file to load.
     *
     * @param resource resource on classpath
     */
    public void setResource(String resource) {
        assertSrcIsJavaResource();
        ((JavaResource) src).setName(resource);
    }

    /**
     * Encoding to use for input, defaults to the platform's default
     * encoding. <p>
     *
     * For a list of possible values see
     * <a href="http://java.sun.com/j2se/1.5.0/docs/guide/intl/encoding.doc.html">
     * http://java.sun.com/j2se/1.5.0/docs/guide/intl/encoding.doc.html
     * </a>.

     *
     * @param encoding The new Encoding value
     */
    public final void setEncoding(final String encoding) {
        this.encoding = encoding;
    }

    /**
     * Set the classpath to use when looking up a resource.
     * @param classpath to add to any existing classpath
     */
    public void setClasspath(Path classpath) {
        assertSrcIsJavaResource();
        ((JavaResource) src).setClasspath(classpath);
    }

    /**
     * Add a classpath to use when looking up a resource.
     * @return The classpath to be configured
     */
    public Path createClasspath() {
        assertSrcIsJavaResource();
        return ((JavaResource) src).createClasspath();
    }

    /**
     * Set the classpath to use when looking up a resource,
     * given as reference to a <path> defined elsewhere
     * @param r The reference value
     */
    public void setClasspathRef(Reference r) {
        assertSrcIsJavaResource();
        ((JavaResource) src).setClasspathRef(r);
    }

    /**
     * get the classpath used by this <code>LoadProperties.
     * @return The classpath
     */
    public Path getClasspath() {
        assertSrcIsJavaResource();
        return ((JavaResource) src).getClasspath();
    }

    /**
     * load Ant properties from the source file or resource
     *
     * @exception BuildException if something goes wrong with the build
     */
    public final void execute() throws BuildException {
        //validation
        if (src == null) {
            throw new BuildException("A source resource is required.");
        }
        if (!src.isExists()) {
            if (src instanceof JavaResource) {
                // dreaded backwards compatibility
                log("Unable to find resource " + src, Project.MSG_WARN);
                return;
            }
            throw new BuildException("Source resource does not exist: " + src);
        }

        BufferedInputStream bis = null;
        Reader instream = null;
        ByteArrayInputStream tis = null;

        try {
            bis = new BufferedInputStream(src.getInputStream());
            if (encoding == null) {
                instream = new InputStreamReader(bis);
            } else {
                instream = new InputStreamReader(bis, encoding);
            }

            ChainReaderHelper crh = new ChainReaderHelper();
            crh.setPrimaryReader(instream);
            crh.setFilterChains(filterChains);
            crh.setProject(getProject());
            instream = crh.getAssembledReader();

            String text = crh.readFully(instream);

            if (text != null) {
                if (!text.endsWith("\n")) {
                    text = text + "\n";
                }

                if (encoding == null) {
                    tis = new ByteArrayInputStream(text.getBytes());
                } else {
                    tis = new ByteArrayInputStream(text.getBytes(encoding));
                }
                final Properties props = new Properties();
                props.load(tis);

                Property propertyTask = new Property();
                propertyTask.bindToOwner(this);
                propertyTask.addProperties(props);
            }

        } catch (final IOException ioe) {
            final String message = "Unable to load file: " + ioe.toString();
            throw new BuildException(message, ioe, getLocation());
        } finally {
            FileUtils.close(bis);
            FileUtils.close(tis);
        }
    }

    /**
     * Adds a FilterChain.
     * @param filter the filter to add
     */
    public final void addFilterChain(FilterChain filter) {
        filterChains.addElement(filter);
    }

    /**
     * Set the source resource.
     * @param a the resource to load as a single element Resource collection.
     * @since Ant 1.7
     */
    public void addConfigured(ResourceCollection a) {
        if (src != null) {
            throw new BuildException("only a single source is supported");
        }
        if (a.size() != 1) {
            throw new BuildException("only single argument resource collections"
                                     + " are supported");
        }
        src = (Resource) a.iterator().next();
    }

    private void assertSrcIsJavaResource() {
        if (src == null) {
            src = new JavaResource();
            src.setProject(getProject());
        } else if (!(src instanceof JavaResource)) {
            throw new BuildException("expected a java resource as source");
        }
    }
}