/**
* The contents of this file are subject to the license and copyright
* detailed in the LICENSE and NOTICE files at the root of the source
* tree and available online at
*
* http://www.dspace.org/license/
*/
package org.dspace.app.sitemap;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintStream;
import java.util.Date;
import java.util.zip.GZIPOutputStream;
/**
* Base class for creating sitemaps of various kinds. A sitemap consists of one
* or more files which list significant URLs on a site for search engines to
* efficiently crawl. Dates of modification may also be included. A sitemap
* index file that links to each of the sitemap files is also generated. It is
* this index file that search engines should be directed towards.
* <P>
* Provides most of the required functionality, subclasses need just implement a
* few methods that specify the "boilerplate" and text for including URLs.
* <P>
* Typical usage:
* <pre>
* AbstractGenerator g = new FooGenerator(...);
* while (...) {
* g.addURL(url, date);
* }
* g.finish();
* </pre>
*
* @author Robert Tansley
*/
public abstract class AbstractGenerator
{
/** Number of files written so far */
protected int fileCount;
/** Number of bytes written to current file */
protected int bytesWritten;
/** Number of URLs written to current file */
protected int urlsWritten;
/** Directory files are written to */
protected File outputDir;
/** Current output */
protected PrintStream currentOutput;
/** Size in bytes of trailing boilerplate */
private int trailingByteCount;
/**
* Initialize this generator to write to the given directory. This must be
* called by any subclass constructor.
*
* @param outputDirIn
* directory to write sitemap files to
*/
public AbstractGenerator(File outputDirIn)
{
fileCount = 0;
outputDir = outputDirIn;
trailingByteCount = getTrailingBoilerPlate().length();
currentOutput = null;
}
/**
* Start writing a new sitemap file.
*
* @throws IOException if IO error
* if an error occurs creating the file
*/
protected void startNewFile() throws IOException
{
String lbp = getLeadingBoilerPlate();
OutputStream fo = new FileOutputStream(new File(outputDir,
getFilename(fileCount)));
if (useCompression())
{
fo = new GZIPOutputStream(fo);
}
currentOutput = new PrintStream(fo);
currentOutput.print(lbp);
bytesWritten = lbp.length();
urlsWritten = 0;
}
/**
* Add the given URL to the sitemap.
*
* @param url
* Full URL to add
* @param lastMod
* Date URL was last modified, or {@code null}
* @throws IOException if IO error
* if an error occurs writing
*/
public void addURL(String url, Date lastMod) throws IOException
{
// Kick things off if this is the first call
if (currentOutput == null)
{
startNewFile();
}
String newURLText = getURLText(url, lastMod);
if (bytesWritten + newURLText.length() + trailingByteCount > getMaxSize()
|| urlsWritten + 1 > getMaxURLs())
{
closeCurrentFile();
startNewFile();
}
currentOutput.print(newURLText);
bytesWritten += newURLText.length();
urlsWritten++;
}
/**
* Finish with the current sitemap file.
*
* @throws IOException if IO error
* if an error occurs writing
*/
protected void closeCurrentFile() throws IOException
{
currentOutput.print(getTrailingBoilerPlate());
currentOutput.close();
fileCount++;
}
/**
* Complete writing sitemap files and write the index files. This is invoked
* when all calls to {@link AbstractGenerator#addURL(String, Date)} have
* been completed, and invalidates the generator.
*
* @return number of sitemap files written.
*
* @throws IOException if IO error
* if an error occurs writing
*/
public int finish() throws IOException
{
if (null != currentOutput)
{
closeCurrentFile();
}
OutputStream fo = new FileOutputStream(new File(outputDir,
getIndexFilename()));
if (useCompression())
{
fo = new GZIPOutputStream(fo);
}
PrintStream out = new PrintStream(fo);
writeIndex(out, fileCount);
out.close();
return fileCount;
}
/**
* Return marked-up text to be included in a sitemap about a given URL.
*
* @param url
* URL to add information about
* @param lastMod
* date URL was last modified, or {@code null} if unknown or not
* applicable
* @return the mark-up to include
*/
public abstract String getURLText(String url, Date lastMod);
/**
* Return the boilerplate at the top of a sitemap file.
*
* @return The boilerplate markup.
*/
public abstract String getLeadingBoilerPlate();
/**
* Return the boilerplate at the end of a sitemap file.
*
* @return The boilerplate markup.
*/
public abstract String getTrailingBoilerPlate();
/**
* Return the maximum size in bytes that an individual sitemap file should
* be.
*
* @return the size in bytes.
*/
public abstract int getMaxSize();
/**
* Return the maximum number of URLs that an individual sitemap file should
* contain.
*
* @return the maximum number of URLs.
*/
public abstract int getMaxURLs();
/**
* Return whether the written sitemap files and index should be
* GZIP-compressed.
*
* @return {@code true} if GZIP compression should be used, {@code false}
* otherwise.
*/
public abstract boolean useCompression();
/**
* Return the filename a sitemap at the given index should be stored at.
*
* @param number
* index of the sitemap file (zero is first).
* @return the filename to write the sitemap to.
*/
public abstract String getFilename(int number);
/**
* Get the filename the index should be written to.
*
* @return the filename of the index.
*/
public abstract String getIndexFilename();
/**
* Write the index file.
*
* @param output
* stream to write the index to
* @param sitemapCount
* number of sitemaps that were generated
* @throws IOException if IO error
* if an IO error occurs
*/
public abstract void writeIndex(PrintStream output, int sitemapCount)
throws IOException;
}