org.apache.wicket.core.util.resource.ClassPathResourceFinder.java Source code

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Here is the source code for org.apache.wicket.core.util.resource.ClassPathResourceFinder.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.wicket.core.util.resource;

import java.net.URL;

import org.apache.wicket.util.file.IResourceFinder;
import org.apache.wicket.util.lang.Args;
import org.apache.wicket.util.resource.IResourceStream;
import org.apache.wicket.util.string.Strings;

/**
 * An {@link IResourceFinder} that looks in a folder in the classpath.
 * 
 * @author Carl-Eric Menzel
 */
public class ClassPathResourceFinder implements IResourceFinder {
    private final String prefix;

    /**
     * @param prefix
     *            The path prefix. May be null or empty to look in the classpath root.
     */
    public ClassPathResourceFinder(String prefix) {
        if (Strings.isEmpty(prefix)) {
            this.prefix = "";
        } else if (prefix.endsWith("/")) {
            this.prefix = prefix;
        } else {
            this.prefix = prefix + "/";
        }
    }

    @Override
    public IResourceStream find(Class<?> clazz, String path) {
        Args.notEmpty(path, "path");
        String fullPath = prefix + (path.startsWith("/") ? path.substring(1) : path);
        IResourceStream resourceStream;
        if (clazz != null) {
            resourceStream = getResourceStreamWithClassLoader(clazz.getClassLoader(), fullPath);
            if (resourceStream != null) {
                return resourceStream;
            }
        }

        // use context classloader when no specific classloader is set
        // (package resources for instance)
        resourceStream = getResourceStreamWithClassLoader(Thread.currentThread().getContextClassLoader(), fullPath);
        if (resourceStream != null) {
            return resourceStream;
        }

        // use Wicket classloader when no specific classloader is set
        resourceStream = getResourceStreamWithClassLoader(getClass().getClassLoader(), fullPath);
        if (resourceStream != null) {
            return resourceStream;
        }

        return null;
    }

    private IResourceStream getResourceStreamWithClassLoader(ClassLoader classLoader, String path) {
        if (classLoader != null) {
            URL url = classLoader.getResource(path);
            if (url != null) {
                return new UrlResourceStream(url);
            }
        }
        return null;
    }

    @Override
    public String toString() {
        if (Strings.isEmpty(prefix)) {
            return "[classpath]";
        } else {
            return "[classpath: " + prefix + "]";
        }
    }
}