org.graphstream.stream.file.FileSinkBase Maven / Gradle / Ivy
/*
* This file is part of GraphStream .
*
* GraphStream is a library whose purpose is to handle static or dynamic
* graph, create them from scratch, file or any source and display them.
*
* This program is free software distributed under the terms of two licenses, the
* CeCILL-C license that fits European law, and the GNU Lesser General Public
* License. You can use, modify and/ or redistribute the software under the terms
* of the CeCILL-C license as circulated by CEA, CNRS and INRIA at the following
* URL or under the terms of the GNU LGPL as published by
* the Free Software Foundation, either version 3 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see
* @author Antoine Dutot
* @author Guilhelm Savin
* @author Hicham Brahimi
*/
package org.graphstream.stream.file;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.Writer;
import java.util.concurrent.atomic.AtomicLong;
import org.graphstream.graph.Edge;
import org.graphstream.graph.Graph;
import org.graphstream.graph.Node;
/**
* Base implementation for graph output to files.
*
*
* This class provides base services to write graphs into files using a specific
* file format. It allows to create an output stream. By default a print stream
* for easy text output, but binary files are possible.
*
*
*
* It handles completely the {@link #writeAll(Graph, OutputStream)},
* {@link #writeAll(Graph, String)}, {@link #begin(OutputStream)},
* {@link #begin(String)}, {@link #flush()} and {@link #end()} methods. You
* should not have to modify or override these.
*
*
*
* In order to implement an output you have to:
*
* - Eventually override {@link #createWriter(OutputStream)} or
* {@link #createWriter(String)} to replace the default instance of PrintStream
* created for you.
* - Implement the {@link #outputHeader()} method. This method is called at
* start, before any graph event is sent to output. Use it to output the header
* of your file.
* - Implement the {@link #outputEndOfFile()} method. This method is called at
* the end of the output, just before closing the output stream. Use it to
* output any terminating syntax for the file format you implement.
* - Implement all the methods of {@link org.graphstream.stream.Sink}. All
* these methods will be called for each graph event and must export these
* events to the file you are writing. You should use the {@link #output} field
* to write to the file. This field has type {@link java.io.OutputStream} but by
* default is of type {@link java.io.PrintStream}, as most of the file format
* will be textual.
*
*
*/
public abstract class FileSinkBase implements FileSink {
// Attribute
/**
* The output.
*/
protected Writer output;
// Command
public void writeAll(Graph graph, String fileName) throws IOException {
begin(fileName);
exportGraph(graph);
end();
}
public void writeAll(Graph graph, OutputStream stream) throws IOException {
begin(stream);
exportGraph(graph);
end();
}
public void writeAll(Graph graph, Writer writer) throws IOException {
begin(writer);
exportGraph(graph);
end();
}
/**
* Echo each element and attribute of the graph to the actual output.
*
* The elements are echoed as add events (add node, add edge, add attribute).
* This method guarantees there are no change or delete events.
*
* @param graph
* The graph to export.
*/
protected void exportGraph(Graph graph) {
final String graphId = graph.getId();
final AtomicLong timeId = new AtomicLong(0);
graph.attributeKeys()
.forEach(key -> graphAttributeAdded(graphId, timeId.getAndIncrement(), key, graph.getAttribute(key)));
graph.nodes().forEach(node -> {
String nodeId = node.getId();
nodeAdded(graphId, timeId.getAndIncrement(), nodeId);
node.attributeKeys().forEach(
key -> nodeAttributeAdded(graphId, timeId.getAndIncrement(), nodeId, key, node.getAttribute(key)));
});
graph.edges().forEach(edge -> {
String edgeId = edge.getId();
edgeAdded(graphId, timeId.getAndIncrement(), edgeId, edge.getNode0().getId(), edge.getNode1().getId(),
edge.isDirected());
edge.attributeKeys().forEach(
key -> edgeAttributeAdded(graphId, timeId.getAndIncrement(), edgeId, key, edge.getAttribute(key)));
});
}
/*
* (non-Javadoc)
*
* @see org.graphstream.stream.file.FileSink#begin(java.lang.String)
*/
public void begin(String fileName) throws IOException {
if (output != null)
throw new IOException("cannot call begin() twice without calling end() before.");
output = createWriter(fileName);
outputHeader();
}
/*
* (non-Javadoc)
*
* @see org.graphstream.stream.file.FileSink#begin(java.io.OutputStream)
*/
public void begin(OutputStream stream) throws IOException {
if (output != null)
throw new IOException("cannot call begin() twice without calling end() before.");
output = createWriter(stream);
outputHeader();
}
/*
* (non-Javadoc)
*
* @see org.graphstream.stream.file.FileSink#begin(java.io.Writer)
*/
public void begin(Writer writer) throws IOException {
if (output != null)
throw new IOException("cannot call begin() twice without calling end() before.");
output = createWriter(writer);
outputHeader();
}
/*
* (non-Javadoc)
*
* @see org.graphstream.stream.file.FileSink#flush()
*/
public void flush() throws IOException {
if (output != null)
output.flush();
}
/*
* (non-Javadoc)
*
* @see org.graphstream.stream.file.FileSink#end()
*/
public void end() throws IOException {
outputEndOfFile();
output.flush();
output.close();
output = null;
}
/**
* Method called at start just after the {@link #output} field is created. Use
* it to output the header of the file.
*
* @throws IOException
* If any I/O error occurs.
*/
protected abstract void outputHeader() throws IOException;
/**
* Method called at the end just before the {@link #output} field is flushed and
* closed. Use it to output any information that closes the file.
*
* @throws IOException
* If any I/O error occurs.
*/
protected abstract void outputEndOfFile() throws IOException;
/**
* Create a a writer from a file name. Override this method if the default
* PrintWriter does not suits your needs. This method is called by
* {@link #begin(String)} and {@link #writeAll(Graph, String)}.
*
* @param fileName
* Name of the file to output to.
* @return A new writer.
* @throws IOException
* If any I/O error occurs.
*/
protected Writer createWriter(String fileName) throws IOException {
return new PrintWriter(fileName);
}
/**
* Create a writer from an existing output stream. Override this method if the
* default PrintWriter does not suits your needs. This method is called by
* {@link #begin(OutputStream)} and {@link #writeAll(Graph, OutputStream)}. This
* method does not create an output stream if the given stream is already
* instance of PrintStream.
*
* @param stream
* An already existing output stream.
* @return A new writer.
* @throws IOException
* If any I/O error occurs.
*/
protected Writer createWriter(OutputStream stream) throws IOException {
return new PrintWriter(stream);
}
/**
* Create a writer from an existing writer. Override this method if the default
* PrintWriter does not suits your needs. This method is called by
* {@link #begin(Writer)} and {@link #writeAll(Graph, Writer)}. This method does
* not create a new writer if the given writer is already instance of
* PrintWriter.
*
* @param writer
* An already existing writer.
* @return A new writer.
* @throws IOException
* If any I/O error occurs.
*/
protected Writer createWriter(Writer writer) throws IOException {
if (writer instanceof PrintWriter)
return writer;
return new PrintWriter(writer);
}
}