property.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.tools.ant.taskdefs;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.Enumeration;
import java.util.Properties;
import java.util.Stack;
import java.util.Vector;

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.PropertyHelper;
import org.apache.tools.ant.Task;
import org.apache.tools.ant.types.Path;
import org.apache.tools.ant.types.Reference;

/**
 * Sets a property by name, or set of properties (from file or
 * resource) in the project.  </p>
 * Properties are immutable: whoever sets a property first freezes it for the
 * rest of the build; they are most definitely not variable.
 * <p>There are five ways to set properties:</p>
 * <ul>
 *   <li>By supplying both the <i>name</i> and <i>value</i> attribute.</li>
 *   <li>By supplying both the <i>name</i> and <i>refid</i> attribute.</li>
 *   <li>By setting the <i>file</i> attribute with the filename of the property
 *     file to load. This property file has the format as defined by the file used
 *     in the class java.util.Properties.</li>
 *   <li>By setting the <i>resource</i> attribute with the resource name of the
 *     property file to load. This property file has the format as defined by the
 *     file used in the class java.util.Properties.</li>
 *   <li>By setting the <i>environment</i> attribute with a prefix to use.
 *     Properties will be defined for every environment variable by
 *     prefixing the supplied name and a period to the name of the variable.</li>
 * </ul>
 * <p>Although combinations of these ways are possible, only one should be used
 * at a time. Problems might occur with the order in which properties are set, for
 * instance.</p>
 * <p>The value part of the properties being set, might contain references to other
 * properties. These references are resolved at the time these properties are set.
 * This also holds for properties loaded from a property file.</p>
 * Properties are case sensitive.
 *
 * @since Ant 1.1
 *
 * @ant.attribute.group name="name" description="One of these, when using the name attribute"
 * @ant.attribute.group name="noname" description="One of these, when not using the name attribute"
 * @ant.task category="property"
 */
public class Property extends Task {

    // CheckStyle:VisibilityModifier OFF - bc
    protected String name;
    protected String value;
    protected File file;
    protected URL url;
    protected String resource;
    protected Path classpath;
    protected String env;
    protected Reference ref;
    protected String prefix;
    private Project fallback;

    protected boolean userProperty; // set read-only properties
    // CheckStyle:VisibilityModifier ON

    /**
     * Constructor for Property.
     */
    public Property() {
        this(false);
    }

    /**
     * Constructor for Property.
     * @param userProperty if true this is a user property
     * @since Ant 1.5
     */
    protected Property(boolean userProperty) {
        this(userProperty, null);
    }

    /**
     * Constructor for Property.
     * @param userProperty if true this is a user property
     * @param fallback a project to use to look for references if the reference is
     *                 not in the current project
     * @since Ant 1.5
     */
    protected Property(boolean userProperty, Project fallback) {
        this.userProperty = userProperty;
        this.fallback = fallback;
    }

    /**
     * The name of the property to set.
     * @param name property name
     */
    public void setName(String name) {
        this.name = name;
    }

    /**
     * Get the property name.
     * @return the property name
     */
    public String getName() {
        return name;
    }

    /**
     * Sets the property to the absolute filename of the
     * given file. If the value of this attribute is an absolute path, it
     * is left unchanged (with / and \ characters converted to the
     * current platforms conventions). Otherwise it is taken as a path
     * relative to the project's basedir and expanded.
     * @param location path to set
     *
     * @ant.attribute group="name"
     */
    public void setLocation(File location) {
        setValue(location.getAbsolutePath());
    }

    /**
     * The value of the property.
     * @param value value to assign
     *
     * @ant.attribute group="name"
     */
    public void setValue(String value) {
        this.value = value;
    }

    /**
     * Get the property value.
     * @return the property value
     */
    public String getValue() {
        return value;
    }

    /**
     * Filename of a property file to load.
     * @param file filename
     *
     * @ant.attribute group="noname"
     */
    public void setFile(File file) {
        this.file = file;
    }

    /**
     * Get the file attribute.
     * @return the file attribute
     */
    public File getFile() {
        return file;
    }

    /**
     * The url from which to load properties.
     * @param url url string
     *
     * @ant.attribute group="noname"
     */
    public void setUrl(URL url) {
        this.url = url;
    }

    /**
     * Get the url attribute.
     * @return the url attribute
     */
    public URL getUrl() {
        return url;
    }

    /**
     * Prefix to apply to properties loaded using <code>file</code>
     * or <code>resource</code>.
     * A "." is appended to the prefix if not specified.
     * @param prefix prefix string
     * @since Ant 1.5
     */
    public void setPrefix(String prefix) {
        this.prefix = prefix;
        if (!prefix.endsWith(".")) {
            this.prefix += ".";
        }
    }

    /**
     * Get the prefix attribute.
     * @return the prefix attribute
     * @since Ant 1.5
     */
    public String getPrefix() {
        return prefix;
    }

    /**
     * Sets a reference to an Ant datatype
     * declared elsewhere.
     * Only yields reasonable results for references
     * PATH like structures or properties.
     * @param ref reference
     *
     * @ant.attribute group="name"
     */
    public void setRefid(Reference ref) {
        this.ref = ref;
    }

    /**
     * Get the refid attribute.
     * @return the refid attribute
     */
    public Reference getRefid() {
        return ref;
    }

    /**
     * The resource name of a property file to load
     * @param resource resource on classpath
     *
     * @ant.attribute group="noname"
     */
    public void setResource(String resource) {
        this.resource = resource;
    }

    /**
     * Get the resource attribute.
     * @return the resource attribute
     */
    public String getResource() {
        return resource;
    }

    /**
     * Prefix to use when retrieving environment variables.
     * Thus if you specify environment=&quot;myenv&quot;
     * you will be able to access OS-specific
     * environment variables via property names &quot;myenv.PATH&quot; or
     * &quot;myenv.TERM&quot;.
     * <p>
     * Note that if you supply a property name with a final
     * &quot;.&quot; it will not be doubled. ie environment=&quot;myenv.&quot; will still
     * allow access of environment variables through &quot;myenv.PATH&quot; and
     * &quot;myenv.TERM&quot;. This functionality is currently only implemented
     * on select platforms. Feel free to send patches to increase the number of platforms
     * this functionality is supported on ;).<br>
     * Note also that properties are case sensitive, even if the
     * environment variables on your operating system are not, e.g. it
     * will be ${env.Path} not ${env.PATH} on Windows 2000.
     * @param env prefix
     *
     * @ant.attribute group="noname"
     */
    public void setEnvironment(String env) {
        this.env = env;
    }

    /**
     * Get the environment attribute.
     * @return the environment attribute
     * @since Ant 1.5
     */
    public String getEnvironment() {
        return env;
    }

    /**
     * The classpath to use when looking up a resource.
     * @param classpath to add to any existing classpath
     */
    public void setClasspath(Path classpath) {
        if (this.classpath == null) {
            this.classpath = classpath;
        } else {
            this.classpath.append(classpath);
        }
    }

    /**
     * The classpath to use when looking up a resource.
     * @return a path to be configured
     */
    public Path createClasspath() {
        if (this.classpath == null) {
            this.classpath = new Path(getProject());
        }
        return this.classpath.createPath();
    }

    /**
     * the classpath to use when looking up a resource,
     * given as reference to a &lt;path&gt; defined elsewhere
     * @param r a reference to a classpath
     */