。java可以直接调用这个类实现画图功能，但是使用这个类的前提是你的电脑已经装了GraphViz软件，你可以在http://www.graphviz.org/Gallery.php下载windows版本，装完后，找到dot.exe所在的路径，我电脑上的是D:\Program Files\Graphviz2.30\bin\dot.exe,

将GraphViz.java中的这一路径改成你电脑上的路径，基本上就可以用了。

package Graphoutput;

// 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;

/**

*

*

Purpose: GraphViz Java API

*

*

*

Description:

*

With this Java class you can simply call dot

* from your Java programs

*

Example usage:

*

*

* 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 );

*

*

*

*

*

* @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 (jabba.laci@gmail.com)

*/

public class GraphViz

{

/**

* 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/bin/dot"; // Linux

private static String DOT = "D:\\Program Files\\Graphviz2.30\\bin\\dot.exe"; // Windows

/**

* 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)

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) { ioe.printStackTrace();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)

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.

*/

public 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) {

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 "}";

}

/**

* 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

通过下面这个类调用graphViz.java

import java.io.File;

public class Proba

{

public static void main(String[] args)

{

Proba p = new Proba();

p.start();

// p.start2();

}

/**

* Construct a DOT graph in memory, convert it

* to image and store the image in the file system.

*/

private void start()

{

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";

// String type = "dot";

// String type = "fig"; // open with xfig

// String type = "pdf";

// String type = "ps";

// String type = "svg"; // open with inkscape

// String type = "png";

// String type = "plain";

File out = new File("/tmp/out." + type); // Linux

// File out = new File("c:/eclipse.ws/graphviz-java-api/out." + type); // Windows

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

}

/**

* Read the DOT source from a file,

* convert to image and store the image in the file system.

*/

private void start2()

{

// String dir = "/home/jabba/eclipse2/laszlo.sajat/graphviz-java-api"; // Linux

// String input = dir + "/sample/simple.dot";

String input = "c:/eclipse.ws/graphviz-java-api/sample/simple.dot"; // Windows

GraphViz gv = new GraphViz();

gv.readSource(input);

System.out.println(gv.getDotSource());

String type = "gif";

// String type = "dot";

// String type = "fig"; // open with xfig

// String type = "pdf";

// String type = "ps";

// String type = "svg"; // open with inkscape

// String type = "png";

// String type = "plain";

File out = new File("/tmp/simple." + type); // Linux

// File out = new File("c:/eclipse.ws/graphviz-java-api/tmp/simple." + type); // Windows

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

}

}

Graphviz介绍

graphviz是贝尔实验室几个计算机牛人设计的一个开源 的图表(计算机科学中数据结构中的图)可视化项目，主要用C语言实现，主要实现了一些图布局算法。通过这些算法，可以将图中的节点在画布上比较均匀的分 布，缩短节点之间的边长，并且尽量的减少边的交叉。

graphviz提供命令式的绘图方式，它提供一个dot语言 用来编写绘图脚本，然后对这个脚本进行解析，分析出其中的定点，边以及子图，然后根据属性进行绘制。具体的可以看一个例子，这个例子来自官方的文档。

digraph G {

main -> parse -> execute;

main -> init;

main -> cleanup;

execute -> make_string;

execute -> printf

init -> make_string;

main -> printf;

execute -> compare;

}

digraph指定该图是一个有向图(directed graph)，->表示一条边，main,parse,execute等是顶点，运行出来的效果很好看，如下图：

需要注意的是，我在这个dot脚本中没有指定任何的关于图的位置的信息，布局器会自动的根据图形的类型进行布局，并最终展现出来。

再来看一个比较复杂，并且是程序员经常使用的功能，数据结构图：

digraph g {

node [shape = record,height=.1];

node0[label = " | G| "];

node1[label = " | E| "];

node2[label = " | B| "];

node3[label = " | F| "];

node4[label = " | R| "];

node5[label = " | H| "];

node6[label = " | Y| "];

node7[label = " | A| "];

node8[label = " | C| "];

"node0":f2 ->"node4":f1;

"node0":f0 ->"node1":f1;

"node1":f0 ->"node2":f1;

"node1":f2 ->"node3":f1;

"node2":f2 ->"node8":f1;

"node2":f0 ->"node7":f1;

"node4":f2 ->"node6":f1;

"node4":f0 ->"node5":f1;

}

运行后的效果如下图所示：

不知道其他的程序员怎样，反正我对命令行情有独钟，比较喜欢这一类的工具。最早接触的计算机系统正是一个没有图形系统的BSD，由此对命令行的，没 有界面的程序都特别感兴趣。

相关的想法

自从使用了graphviz以后，一直想着把这个好东西移植到java下来，大概的思想跟graphviz类似：

解析dot脚本，生成图的对象，这个图中包括节点，边以及子图等对象，这些对象上都绑定着相应的属性

将解析出来的图对象发送给layout engine进行处理，layout engine可以选择布局策略，比如流布局等

从layout engine中得到布局后的图对象，并交给image engine处理，得到最终结果，负责展示或者保存等

dot 的语法定义比较简单，我已经用javacc构造了一个dot的分析器，现在可以从dot文件中构建出图对象出来，不过还需要进一步完善，可以看看这个 BNF定义：

graph -> [strict] (digraph|graph) id'{'stmt-list'}'

stmt-list -> [stmt [';'] [stmt-list] ]

stmt -> attr-stmt | node-stmt | edge-stmt | subgraph | id '='id

attr-stmt -> (graph | node | edge) attr-list

attr-list -> '['[a-list]']'[attr-list]

a-list -> id '='id [','][a-list]

node-stmt -> node-id [attr-list]

node-id -> id [port]

port -> port-location [port-angle] | port-angle [port-location]

port-location -> ':'id |':''('id','id')'

port-angle ->'@'id

edge-stmt -> (node-id | subgraph) edgeRHS [attr-list]

edgeRHS -> edgeop (node-id | subgraph) [edgeRHS]

subgraph -> [subgraph id] '{'stmt-list'}'| subgraph id

(最近老是感觉时间不够用，有很多有意思的项目要做，比如要完善前几天说的那个bbms(Bus Based Message Service), 再比如修改用Swing和Smack做一个jabber的客户端jTalk，都是很有搞头的，唉，扯远了。)

当然graphviz的功能不至于此，它提供一个lib，可以用来将绘图引擎嵌入在自己的应用中。这是一个很有意义的事，我们可以不必掌握布局部分 的复杂算法，把精力放在业务逻辑部分，将最后的图对象交给这个引擎来处理即可。当然，如果你正好和我一样，想了解其神奇的布局算法，不妨翻翻它的源码，欢 迎交流之至。

我在周末分析了下graphviz的内部结构，并建立了一个java的项目jraph，用来做简单的移植，主要是学习之用，其实，Java的图库还是相当丰富的，比如JGraph ，JGraphT，Prefuse，TouchGraph等等，用来做项目当然是很便捷的，但是我还是比较喜欢看着一个算法被自己实现的过程，特别是这种 比较神奇的算法，哈哈。

预期中的API如下：

publicstaticvoidmain(String[] args){

Parser parser = newGCodeParser("file.g");

GraphSet gs = parser.parse();

GraphSet layouted =

newGraphLayoutEngine(gs).layout();

ImageEngine imgEngine =

newGraphImageEngine(layouted);

imgEngine.export(0);

}

同graphviz一样，先调用分析器构造出图的集合GraphSet(包括多个图，每个图中包括Vertex，Edge，及SubGraph)， 然后进行布局，最后将通过布局后的GraphSet绘制结果。目前完成了框架的设计部分，分析器部分基本完成，layout部分只实现了一个策略，即force-based布局算法，不过layout engine被设计成可以插拔的模型，如果有了新的算法实现，可以很容易的整合起来。

dot.exe  -Tpng -o new.png -Kdot new.dot