net.sourceforge.javadpkg.io.impl.DataTempFileSwap Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of dpkg Show documentation
The library for reading and writing Debian Packages.
There is a newer version: 1.0.5
/*
 * dpkg - Debian Package library and the Debian Package Maven plugin
 * (c) Copyright 2016 Gerrit Hohl
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
package net.sourceforge.javadpkg.io.impl;

import java.io.File;
import java.io.IOException;

import net.sourceforge.javadpkg.io.DataSource;
import net.sourceforge.javadpkg.io.DataSwap;
import net.sourceforge.javadpkg.io.DataTarget;


/**
 * 
 * A {@link DataSwap} implementation which uses temporary files for storing the
 * data.
 * 
 *
 * @see File#createTempFile(String, String)
 * @author Gerrit Hohl ([email protected])
 * @version 1.0, 29.04.2016 by Gerrit Hohl
 */
public class DataTempFileSwap implements DataSwap {
	
	
	/** The name. */
	private String		name;
	/** The prefix. */
	private String		prefix;
	/** The suffix. */
	private String		suffix;
	
	/** The file. */
	private File		file;
	/** The target. */
	private DataTarget	target;
	/** The source. */
	private DataSource	source;
	/** The flag if the swap was closed. */
	private boolean		closed;
	
	
	/**
	 * 
	 * Creates a swap.
	 * 
	 *
	 * @param name
	 *            The name of the target and source.
	 * @throws IllegalArgumentException
	 *             If the name is null.
	 */
	public DataTempFileSwap(String name) {
		super();
		
		if (name == null)
			throw new IllegalArgumentException("Argument name is null.");
		
		this.name = name;
		this.prefix = "data-temp-file-swap-";
		this.suffix = ".tmp";

		this.file = null;
		this.target = null;
		this.source = null;
		this.closed = false;
	}
	
	
	/**
	 * 
	 * Creates a swap.
	 * 
	 *
	 * @param name
	 *            The name of the target and source.
	 * @param prefix
	 *            The prefix of the filename.
	 * @param suffix
	 *            The suffix of the filename.
	 * @throws IllegalArgumentException
	 *             If any of the parameters are null.
	 */
	public DataTempFileSwap(String name, String prefix, String suffix) {
		this(name);
		
		if (prefix == null)
			throw new IllegalArgumentException("Argument prefix is null.");
		if (suffix == null)
			throw new IllegalArgumentException("Argument suffix is null.");
		
		this.prefix = prefix;
		this.suffix = suffix;
	}
	
	
	@Override
	public DataTarget getTarget() throws IOException {
		if (this.closed)
			throw new IllegalStateException("Can't return the target because the swap |" + this.name + "| was already closed.");
		if (this.source != null)
			throw new IllegalStateException("Can't return the target of the swap |" + this.name
					+ "| because the corresponding source is already open.");
		if (this.target != null)
			return this.target;
		
		this.file = File.createTempFile(this.prefix, this.suffix);
		this.target = new DataFileTarget(this.file);
		return this.target;
	}


	@Override
	public DataSource getSource() throws IOException {
		if (this.closed)
			throw new IllegalStateException("Can't return the source because the swap |" + this.name + "| was already closed.");
		if (this.source != null)
			return this.source;
		if (this.target == null)
			throw new IllegalStateException("Can't return the source of the swap |" + this.name
					+ "| because the corresponding target hasn't been opened yet.");
		
		this.target.close();
		this.source = new DataFileSource(this.file, true);
		return this.source;
	}
	
	
	@Override
	public void close() throws IOException {
		try {
			if (this.target != null) {
				try {
					this.target.close();
				} catch (IOException e) {
					throw new IOException("Couldn't close target of swap |" + this.name + "|: " + e.getMessage(), e);
				}
			}
			if (this.source != null) {
				try {
					this.source.close();
				} catch (IOException e) {
					throw new IOException("Couldn't close source of swap |" + this.name + "|: " + e.getMessage(), e);
				}
			}
			if ((this.file != null) && this.file.exists()) {
				if (!this.file.delete())
					throw new IOException(
							"Couldn't delete swap |" + this.name + "| (Path: |" + this.file.getAbsolutePath() + "|).");
			}
		} finally {
			this.file = null;
			this.target = null;
			this.source = null;
			this.closed = true;
		}
	}


}