com.redhat.rcm.maven.plugin.buildmetadata.maven.MavenPropertyHelper.java Source code

Introduction

Here is the source code for com.redhat.rcm.maven.plugin.buildmetadata.maven.MavenPropertyHelper.java

Source

/*
 * Copyright 2006-2014 smartics, Kronseder & Reiner GmbH
 *
 * Licensed 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 com.redhat.rcm.maven.plugin.buildmetadata.maven;

import java.lang.reflect.InvocationTargetException;
import java.util.Properties;

import org.apache.commons.beanutils.PropertyUtils;
import org.apache.maven.project.MavenProject;

/**
 * Fetches properties from a Maven project. This includes properties of the
 * Maven project instance as well as properties from its properties section.
 * <p>
 * It is allowed to change the project passed to the helper instance after
 * creation of the instance as long as the caller makes sure that it is not
 * changed within a call of this instance. No synchronization is cared for by
 * this instance.
 * </p>
 *
 * @author <a href="mailto:robert.reiner@smartics.de">Robert Reiner</a>
 * @version $Revision:591 $
 */
public final class MavenPropertyHelper {
    // ********************************* Fields *********************************

    // --- constants ------------------------------------------------------------

    /**
     * All properties referring to the Maven project instance start with this
     * prefix.
     * <p>
     * The value of this constant is {@value}.
     * </p>
     */
    private static final String PROJECT_PROPERTY_NAME_PREFIX = "project.";

    /**
     * The length of the {@link #PROJECT_PROPERTY_NAME_PREFIX project property
     * prefix}.
     * <p>
     * The value of this constant is {@value}.
     * </p>
     */
    private static final int PROJECT_PROPERTY_NAME_PREFIX_LENGTH = PROJECT_PROPERTY_NAME_PREFIX.length();

    // --- members --------------------------------------------------------------

    /**
     * The project to fetch properties from.
     */
    private final MavenProject project;

    // ****************************** Initializer *******************************

    // ****************************** Constructors ******************************

    /**
     * Default constructor.
     *
     * @param project the project to fetch properties from.
     */
    public MavenPropertyHelper(final MavenProject project) {
        if (project == null) {
            throw new NullPointerException("The property helper requires the project reference to be not 'null'.");
        }
        this.project = project;
    }

    // ****************************** Inner Classes *****************************

    // ********************************* Methods ********************************

    // --- init -----------------------------------------------------------------

    // --- get&set --------------------------------------------------------------

    // --- business -------------------------------------------------------------

    /**
     * Returns the property value specified by the given name.
     *
     * @param name the name of the property to return.
     * @return the property value for the given {@code name}.
     */
    public String getProperty(final String name) {
        if (name == null) {
            throw new NullPointerException("Name of requested property must not be 'null'");
        }

        String value = null;
        if (isProjectProperty(name)) {
            value = getProjectProperty(name);
        }
        if (value == null) {
            value = getPropertiesProperty(name);
        }
        return value;
    }

    private boolean isProjectProperty(final String name) {
        return name != null && name.length() >= PROJECT_PROPERTY_NAME_PREFIX_LENGTH
                && name.startsWith(PROJECT_PROPERTY_NAME_PREFIX);
    }

    /**
     * Returns a property from the project instance.
     */
    private String getProjectProperty(final String name) {
        final String projectName = name.substring(PROJECT_PROPERTY_NAME_PREFIX_LENGTH);
        if (PropertyUtils.isReadable(project, projectName)) {
            try {
                return getProjectProperty(project, projectName);
            } catch (final Exception e) {
                throw new IllegalStateException("Cannot access project property '" + name + "'.");
            }
        }

        return null;
    }

    private static String getProjectProperty(final MavenProject project, final String projectName)
            throws IllegalAccessException, InvocationTargetException, NoSuchMethodException {
        if (project != null) {
            final Object value = PropertyUtils.getProperty(project, projectName);
            if (value != null) {
                return String.valueOf(value);
            } else {
                return getProjectProperty(project.getParent(), projectName);
            }
        }
        return null;
    }

    /**
     * Returns a property from the <code>properties</code> section.
     */
    private String getPropertiesProperty(final String name) {
        return getPropertiesProperty(project, name);
    }

    private static String getPropertiesProperty(final MavenProject project, final String name) {
        String value = null;
        final Properties properties = project.getProperties();
        if (properties != null) {
            value = properties.getProperty(name);
        }

        if (value == null) {
            value = getPropertiesPropertyFromParent(project, name);
        }

        return value;
    }

    private static String getPropertiesPropertyFromParent(final MavenProject project, final String name) {
        final String value;
        final MavenProject parentProject = project.getParent();
        if (parentProject != null) {
            value = getPropertiesProperty(parentProject, name);
        } else {
            value = null;
        }
        return value;
    }

    // --- object basics --------------------------------------------------------

}