Java tutorial
package com.epam.controllers.pages.graphviz; // GraphViz.java - a simple API to call dot from Java programs /*$Id$*/ /* ****************************************************************************** * * * (c) Copyright 2003 Laszlo Szathmary * * * * This program is free software; you can redistribute it and/or modify it * * under the terms of the GNU Lesser General Public License as published by * * the Free Software Foundation; either version 2.1 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, write to the Free Software Foundation, * * Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * * * ****************************************************************************** */ import java.io.BufferedReader; import java.io.DataInputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.FileWriter; import java.io.InputStreamReader; import org.apache.commons.lang.StringUtils; import org.apache.log4j.Logger; /** * <dl> * <dt>Purpose: GraphViz Java API * <dd> * * <dt>Description: * <dd> With this Java class you can simply call dot * from your Java programs * <dt>Example usage: * <dd> * <pre> * GraphViz gv = new GraphViz(); * gv.addln(gv.start_graph()); * gv.addln("A -> B;"); * gv.addln("A -> C;"); * gv.addln(gv.end_graph()); * System.out.println(gv.getDotSource()); * * String type = "gif"; * File out = new File("out." + type); // out.gif in this example * gv.writeGraphToFile( gv.getGraph( gv.getDotSource(), type ), out ); * </pre> * </dd> * * </dl> * * @version v0.4, 2011/02/05 (February) -- Patch of Keheliya Gallaba is added. Now you * can specify the type of the output file: gif, dot, fig, pdf, ps, svg, png, etc. * @version v0.3, 2010/11/29 (November) -- Windows support + ability * to read the graph from a text file * @version v0.2, 2010/07/22 (July) -- bug fix * @version v0.1, 2003/12/04 (December) -- first release * @author Laszlo Szathmary (<a href="jabba.laci@gmail.com">jabba.laci@gmail.com</a>) */ public class GraphViz { private static final Logger log = Logger.getLogger(GraphViz.class.getName()); /** * The dir. where temporary files will be created. */ //private static String TEMP_DIR = "/tmp"; // Linux private static String TEMP_DIR = "c:/temp"; // Windows /** * Where is your dot program located? It will be called externally. */ //private static String DOT = "/usr/local/bin/dot"; // MAC //private static String DOT = "/usr/bin/dot"; // Linux private static String DOT = "C:\\Program Files (x86)\\Graphviz2.38\\bin\\dot.exe"; // Windows public static final String GRAPH_START = "digraph G {"; public static final String GRAPH_END = "}"; /** * The source of the graph written in dot language. */ private StringBuilder graph = new StringBuilder(); /** * Constructor: creates a new GraphViz object that will contain * a graph. */ public GraphViz() { } /** * Returns the graph's source description in dot language. * @return Source of the graph in dot language. */ public String getDotSource() { return graph.toString(); } /** * Adds a string to the graph's source (without newline). */ public void add(String line) { graph.append(line); } /** * Adds a string to the graph's source (with newline). */ public void addln(String line) { graph.append(line + "\n"); } /** * Adds a newline to the graph's source. */ public void addln() { graph.append('\n'); } /** * Returns the graph as an image in binary format. * @param dot_source Source of the graph to be drawn. * @param type Type of the output image to be produced, e.g.: gif, dot, fig, pdf, ps, svg, png. * @return A byte array containing the image of the graph. */ public byte[] getGraph(String dot_source, String type) { File dot; byte[] img_stream = null; try { dot = writeDotSourceToFile(dot_source); if (dot != null) { img_stream = get_img_stream(dot, type); if (dot.delete() == false) log.warn("Warning: " + dot.getAbsolutePath() + " could not be deleted!"); return img_stream; } return null; } catch (java.io.IOException ioe) { return null; } } /** * Writes the graph's image in a file. * @param img A byte array containing the image of the graph. * @param file Name of the file to where we want to write. * @return Success: 1, Failure: -1 */ public int writeGraphToFile(byte[] img, String file) { File to = new File(file); return writeGraphToFile(img, to); } /** * Writes the graph's image in a file. * @param img A byte array containing the image of the graph. * @param to A File object to where we want to write. * @return Success: 1, Failure: -1 */ public int writeGraphToFile(byte[] img, File to) { try { FileOutputStream fos = new FileOutputStream(to); fos.write(img); fos.close(); } catch (java.io.IOException ioe) { return -1; } return 1; } /** * It will call the external dot program, and return the image in * binary format. * @param dot Source of the graph (in dot language). * @param type Type of the output image to be produced, e.g.: gif, dot, fig, pdf, ps, svg, png. * @return The image of the graph in .gif format. */ private byte[] get_img_stream(File dot, String type) { File img; byte[] img_stream = null; try { img = File.createTempFile("graph_", "." + type, new File(GraphViz.TEMP_DIR)); Runtime rt = Runtime.getRuntime(); // patch by Mike Chenault String[] args = { DOT, "-T" + type, dot.getAbsolutePath(), "-o", img.getAbsolutePath() }; Process p = rt.exec(args); p.waitFor(); FileInputStream in = new FileInputStream(img.getAbsolutePath()); img_stream = new byte[in.available()]; in.read(img_stream); // Close it if we need to if (in != null) in.close(); if (img.delete() == false) log.warn("Warning: " + img.getAbsolutePath() + " could not be deleted!"); } catch (java.io.IOException ioe) { log.warn("Error: in I/O processing of tempfile in dir " + GraphViz.TEMP_DIR + "\n"); log.warn(" or in calling external command"); log.error("stacktrace", ioe); } catch (java.lang.InterruptedException ie) { log.error("Error: the execution of the external program was interrupted", ie); } return img_stream; } /** * Writes the source of the graph in a file, and returns the written file * as a File object. * @param str Source of the graph (in dot language). * @return The file (as a File object) that contains the source of the graph. */ private File writeDotSourceToFile(String str) throws java.io.IOException { File temp; try { temp = File.createTempFile("graph_", ".dot.tmp", new File(GraphViz.TEMP_DIR)); FileWriter fout = new FileWriter(temp); fout.write(str); fout.close(); } catch (Exception e) { log.error("Error: I/O error while writing the dot source to temp file!", e); return null; } return temp; } /** * Returns a string that is used to start a graph. * @return A string to open a graph. */ public String start_graph() { return GRAPH_START; } /** * Returns a string that is used to end a graph. * @return A string to close a graph. */ public String end_graph() { return GRAPH_END; } /** * Read a DOT graph from a text file. * * @param input Input text file containing the DOT graph * source. */ public void readSource(String input) { StringBuilder sb = new StringBuilder(); try { FileInputStream fis = new FileInputStream(input); DataInputStream dis = new DataInputStream(fis); BufferedReader br = new BufferedReader(new InputStreamReader(dis)); String line; while ((line = br.readLine()) != null) { sb.append(line); } dis.close(); } catch (Exception e) { log.error("Error: ", e); } this.graph = sb; } /** * read from a string * @param dot */ public void readString(String dot) { this.graph = new StringBuilder(dot); } /** * is a valid dot source * @param dot * @return */ public static boolean isValidDotText(String dot) { return StringUtils.isNotBlank(dot) && (dot.indexOf(GRAPH_START) > -1); } } // end of class GraphViz