com.google.code.mojo.license.util.resource.ResourceFinder Maven / Gradle / Ivy

/**
 * Copyright (C) 2008 http://code.google.com/p/maven-license-plugin/
 *
 * 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.google.code.mojo.license.util.resource;

import org.apache.maven.plugin.MojoFailureException;

import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.List;

/**
 * Date: 26-Feb-2008

 * Author: Mathieu Carbou ([email protected])
 */
public final class ResourceFinder {
    private final File basedir;
    private CustomClassLoader compileClassPath;
    private CustomClassLoader pluginClassPath;

    public ResourceFinder(File basedir) {
        this.basedir = basedir;
    }

    public void setCompileClassPath(List classpath) {
        compileClassPath = new CustomClassLoader();
        if (classpath != null) {
            for (String absolutePath : classpath) {
                compileClassPath.addFolder(absolutePath);
            }
        }
    }

    public void setPluginClassPath(ClassLoader classLoader) {
        pluginClassPath = new CustomClassLoader(classLoader);
    }

    /**
     * Find a resource by searching:

     * 1. In the filesystem, relative to basedir

     * 2. In the filesystem, as an absolute path (or relative to current execution directory)

     * 3. In project classpath

     * 4. In plugin classpath

     * 5. As a URL
     *
     * @param resource The resource to get
     * @return A valid URL
     * @throws MojoFailureException If the resource is not found
     */
    public URL findResource(String resource) throws MojoFailureException {
        // first search relatively to the base directory
        URL res = toURL(new File(basedir, resource));
        if (res != null) {
            return res;
        }

        // if not found, search for absolute location on file system, or relative to execution dir
        res = toURL(new File(resource));
        if (res != null) {
            return res;
        }

        // if not found, try the classpaths
        String cpResource = resource.startsWith("/") ? resource.substring(1) : resource;

        // tries compile claspath of projet
        res = compileClassPath.getResource(cpResource);
        if (res != null) {
            return res;
        }

        // tries this plugin classpath
        res = pluginClassPath.getResource(cpResource);
        if (res != null) {
            return res;
        }

        // otherwise, tries to return a valid URL
        try {
            res = new URL(resource);
            res.openStream().close();
            return res;
        }
        catch (Exception e) {
            throw new MojoFailureException("Resource " + resource + " not found in file system, classpath or URL: " + e.getMessage(), e);
        }
    }

    private URL toURL(File file) {
        if (file.exists() && file.canRead()) {
            try {
                return file.toURI().toURL();
            }
            catch (MalformedURLException e) {
            }
        }
        return null;
    }

}