How to call GraphViz from java

Question

How to call GraphViz from java and how to call GraphViz functions using java? What are the necessary jar files that are to be included inorder to access the GraphViz library for building a dot graph? Is there any sample program for generating a dot graph

Answer 1

Check this API, It is simple and has several output format (i.e. pdf gif ..etc).

EDIT May 2016: As many commented that the API is not available anymore; Here its source code:

First there is config.properties file that you need to create and copy paste the following:

##############################################################
#                    Linux Configurations                    #
##############################################################
# The dir. where temporary files will be created.
tempDirForLinux = /tmp
# Where is your dot program located? It will be called externally.
dotForLinux = /usr/bin/dot

##############################################################
#                   Windows Configurations                   #
##############################################################
# The dir. where temporary files will be created.
tempDirForWindows = c:/temp
# Where is your dot program located? It will be called externally.
dotForWindows = "c:/Program Files (x86)/Graphviz 2.28/bin/dot.exe"

##############################################################
#                    Mac Configurations                      #
##############################################################
# The dir. where temporary files will be created.
tempDirForMacOSX = /tmp
# Where is your dot program located? It will be called externally.
dotForMacOSX = /usr/local/bin/dot

Then Graphviz.java source code

// GraphViz.java - a simple API to call dot from Java programs

/*$Id$*/
/*
 ******************************************************************************
 *                                                                            *
 *                    (c) Copyright 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.BufferedWriter;
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 java.util.Properties;

/**
 * <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 v0.5.1, 2013/03/18 (March) -- Patch of Juan Hoyos (Mac support)
 * @version v0.5, 2012/04/24 (April) -- Patch of Abdur Rahman (OS detection + start subgraph + 
 * read config file)
 * @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="[email protected]">[email protected]</a>)
 */
public class GraphViz
{
    /**
     * Detects the client's operating system.
     */
    private final static String osName = System.getProperty("os.name").replaceAll("\\s","");

    /**
     * Load the config.properties file.
     */
    private final static String cfgProp = "/Users/seteropere/NetBeansProjects/TestApplication/src/config.properties";
    private final static Properties configFile = new Properties() {
        private final static long serialVersionUID = 1L; {
            try {
                load(new FileInputStream(cfgProp));
            } catch (Exception e) {}
        }
    };

    /**
     * The dir. where temporary files will be created.
     */
  private static String TEMP_DIR = "/Users/seteropere/NetBeansProjects/TestApplication";

    /**
     * Where is your dot program located? It will be called externally.
     */
  private static String DOT = configFile.getProperty("dotFor" + osName);

    /**
     * The image size in dpi. 96 dpi is normal size. Higher values are 10% higher each.
     * Lower values 10% lower each.
     * 
     * dpi patch by Peter Mueller
     */
    private int[] dpiSizes = {46, 51, 57, 63, 70, 78, 86, 96, 106, 116, 128, 141, 155, 170, 187, 206, 226, 249};

    /**
     * Define the index in the image size array.
     */
    private int currentDpiPos = 7;

    /**
     * Increase the image size (dpi).
     */
    public void increaseDpi() {
        if ( this.currentDpiPos < (this.dpiSizes.length - 1) ) {
            ++this.currentDpiPos;
        }
    }

    /**
     * Decrease the image size (dpi).
     */
    public void decreaseDpi() {
        if (this.currentDpiPos > 0) {
            --this.currentDpiPos;
        }
    }

    public int getImageDpi() {
        return this.dpiSizes[this.currentDpiPos];
    }

    /**
     * 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 this.graph.toString();
    }

    /**
     * Adds a string to the graph's source (without newline).
     */
    public void add(String line) {
        this.graph.append(line);
    }

    /**
     * Adds a string to the graph's source (with newline).
     */
    public void addln(String line) {
        this.graph.append(line + "\n");
    }

    /**
     * Adds a newline to the graph's source.
     */
    public void addln() {
        this.graph.append('\n');
    }

    public void clearGraph(){
        this.graph = new StringBuilder();
    }

    /**
     * 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) 
                    System.err.println("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, "-Gdpi="+dpiSizes[this.currentDpiPos], 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) 
                System.err.println("Warning: " + img.getAbsolutePath() + " could not be deleted!");
        }
        catch (java.io.IOException ioe) {
            System.err.println("Error:    in I/O processing of tempfile in dir " + GraphViz.TEMP_DIR+"\n");
            System.err.println("       or in calling external command");
            ioe.printStackTrace();
        }
        catch (java.lang.InterruptedException ie) {
            System.err.println("Error: the execution of the external program was interrupted");
            ie.printStackTrace();
        }

        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("dorrr",".dot", new File(GraphViz.TEMP_DIR));
            FileWriter fout = new FileWriter(temp);
            fout.write(str);
                       BufferedWriter br=new BufferedWriter(new FileWriter("dotsource.dot"));
                       br.write(str);
                       br.flush();
                       br.close();
            fout.close();
        }
        catch (Exception e) {
            System.err.println("Error: I/O error while writing the dot source to temp file!");
            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 "digraph G {";
    }

    /**
     * Returns a string that is used to end a graph.
     * @return A string to close a graph.
     */
    public String end_graph() {
        return "}";
    }

    /**
     * Takes the cluster or subgraph id as input parameter and returns a string
     * that is used to start a subgraph.
     * @return A string to open a subgraph.
     */
    public String start_subgraph(int clusterid) {
        return "subgraph cluster_" + clusterid + " {";
    }

    /**
     * Returns a string that is used to end a graph.
     * @return A string to close a graph.
     */
    public String end_subgraph() {
        return "}";
    }

    /**
     * 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) {
            System.err.println("Error: " + e.getMessage());
        }

        this.graph = sb;
    }

} // end of class GraphViz

An example is:

public static void createDotGraph(String dotFormat,String fileName)
{
    GraphViz gv=new GraphViz();
    gv.addln(gv.start_graph());
    gv.add(dotFormat);
    gv.addln(gv.end_graph());
   // String type = "gif";
    String type = "pdf";
  // gv.increaseDpi();
    gv.decreaseDpi();
    gv.decreaseDpi();
    File out = new File(fileName+"."+ type); 
    gv.writeGraphToFile( gv.getGraph( gv.getDotSource(), type ), out );
}

Invoking it like this:

    public static void main(String[] args) throws Exception {
        String dotFormat="1->2;1->3;1->4;4->5;4->6;6->7;5->7;3->8;3->6;8->7;2->8;2->5;";
        createDotGraph(dotFormat, "DotGraph");
 }

which will create dotsource.dot and DotGraph.pdf representing a cubic graph in the directory you specified. Remember: you just need to change the values of two parameters in the code: cfgProp and TEMP_DIR.

Hope that helps.

Answer 2

I've answered similar question here: Calling Graphviz dot from Java

You can use the Graphviz Java API class which is a wrapper for Runtime.exec(), this is if you have the dot binaries on the same server as your Java App.

If you don't have dot installed on the server or if you are using an environment like Google AppEngine where you can't install dot binaries locally then you can use Graphviz Server, a lightweight Java based HTTP server, you still need to install the dot binaries on the server on which you run Graphviz Server.

The following is a code example using the Graphviz Java API class

// graphTypeis one of: pdf, svg, png, etc...

private static final String TEMP_PATH = "/tmp/graph.";

private File generateGraph(String dot, String graphType) {

    GraphViz gv = new GraphViz();
    gv.readString(dot);

    File out = new File(TEMP_PATH + graphType);   // Linux

    gv.writeGraphToFile( gv.getGraph( gv.getDotSource(), graphType ), out );

    return out;
}

Answer 3

There seems to be a solution for graphviz in java without dot binary: https://github.com/nidi3/graphviz-java

From the github page it says:

To execute the graphviz layout engine, one of these options is used:

• If the machine has graphviz installed and a dot command is available, spawn a new process running dot.
• Use this javascript version of graphviz and execute it on the V8 javascript engine. This is done with the bundled J2V8 library.
• Alternatively, the javascript can be executed on Java's own Nashorn or GraalVM engine.

I have not tested it yet though