src/main/java/org/apache/maven/shared/io/location/FileLocation.java

/*
 * 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.maven.shared.io.location;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

/**
 * file location implementation.
 */
public class FileLocation implements Location {

    private File file;
    private FileChannel channel;
    private final String specification;
    private FileInputStream stream;

    /**
     * @param file {@link File}
     * @param specification spec.
     */
    public FileLocation(File file, String specification) {
        this.file = file;
        this.specification = specification;
    }

    /**
     * @param specification spec.
     */
    protected FileLocation(String specification) {
        this.specification = specification;
    }

    /** {@inheritDoc} */
    public void close() {
        if ((channel != null) && channel.isOpen()) {
            try {
                channel.close();
            } catch (IOException e) {
                // swallow it.
            }
        }

        if (stream != null) {
            try {
                stream.close();
            } catch (IOException e) {
                // swallow it.
            }
        }
    }

    /** {@inheritDoc} */
    public File getFile() throws IOException {
        initFile();

        return unsafeGetFile();
    }

    /**
     * @return {@link File}
     */
    protected File unsafeGetFile() {
        return file;
    }

    /**
     * initialize file.
     * @throws IOException in case error.
     */
    protected void initFile() throws IOException {
        // TODO: Log this in the debug log-level...
        if (file == null) {
            file = new File(specification);
        }
    }

    /**
     * @param file {@link File}
     */
    protected void setFile(File file) {
        if (channel != null) {
            throw new IllegalStateException("Location is already open; cannot setFile(..).");
        }

        this.file = file;
    }

    /** {@inheritDoc} */
    public String getSpecification() {
        return specification;
    }

    /** {@inheritDoc} */
    public void open() throws IOException {
        if (stream == null) {
            initFile();

            stream = new FileInputStream(file);
            channel = stream.getChannel();
        }
    }

    /** {@inheritDoc} */
    public int read(ByteBuffer buffer) throws IOException {
        open();
        return channel.read(buffer);
    }

    /** {@inheritDoc} */
    public int read(byte[] buffer) throws IOException {
        open();
        return channel.read(ByteBuffer.wrap(buffer));
    }

    /** {@inheritDoc} */
    public InputStream getInputStream() throws IOException {
        open();
        return stream;
    }
}