I decided on a few inconveniences.

src/info/dawelbeit/graphviz/dot/GraphViz.java

@@ -31,10 +31,15 @@
 import java.io.FileOutputStream;
 import java.io.FileWriter;
 import java.io.InputStreamReader;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 import org.apache.commons.lang3.StringUtils;
 import org.apache.log4j.Logger;
 
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
 /**
  * <dl>
  * <dt>Purpose: GraphViz Java API
@@ -63,15 +68,15 @@
  *
  * @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 
+ * @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.
@@ -84,10 +89,10 @@ public class GraphViz
 	 */
 	//private static String DOT = "/usr/local/bin/dot"; // MAC
 	private static String DOT = "/usr/bin/dot";	// Linux
-	//   private static String DOT = "c:/Program Files/Graphviz2.26.3/bin/dot.exe";	// Windows
-	
+	//private static String DOT = "C:/Program Files/Graphviz/bin/dot.exe";	// Windows
+
 	public static final String GRAPH_START = "digraph G {";
-	
+
 	public static final String GRAPH_END = "}";
 
 	/**
@@ -147,7 +152,7 @@ public byte[] getGraph(String dot_source, String type)
 			if (dot != null)
 			{
 				img_stream = get_img_stream(dot, type);
-				if (dot.delete() == false) 
+				if (dot.delete() == false)
 					log.warn("Warning: " + dot.getAbsolutePath() + " could not be deleted!");
 				return img_stream;
 			}
@@ -211,7 +216,7 @@ private byte[] get_img_stream(File dot, String type)
 			// Close it if we need to
 			if( in != null ) in.close();
 
-			if (img.delete() == false) 
+			if (img.delete() == false)
 				log.warn("Warning: " + img.getAbsolutePath() + " could not be deleted!");
 		}
 		catch (java.io.IOException ioe) {
@@ -266,7 +271,7 @@ public String end_graph() {
 
 	/**
 	 * Read a DOT graph from a text file.
-	 * 
+	 *
 	 * @param input Input text file containing the DOT graph
 	 * source.
 	 */
@@ -284,7 +289,7 @@ public void readSource(String input)
 				sb.append(line);
 			}
 			dis.close();
-		} 
+		}
 		catch (Exception e) {
 			log.error("Error: ", e);
 		}
@@ -299,14 +304,32 @@ public void readSource(String input)
 	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);
+		// return StringUtils.isNotBlank(dot) && (dot.indexOf(GRAPH_START) > -1);
+		return StringUtils.isNotBlank(dot) && (checkGraphStart(dot));
+	}
+
+	private static boolean checkGraphStart(String dot) {
+		boolean ret_val;
+
+		// "digraph" 다음에 오는 단어를 찾는 정규 표현식 패턴
+        String patternString = "digraph\\s+(\\w+)\\s*\\{";
+
+        Pattern pattern = Pattern.compile(patternString);
+        Matcher matcher = pattern.matcher(dot);
+
+        if (matcher.find()) {
+            ret_val = true;
+        } else {
+            ret_val = false;
+        }
+		return ret_val;
 	}
 
 } // end of class GraphViz

src/info/dawelbeit/graphviz/dot/HttpDotGraphMessageHandler.java

@@ -27,22 +27,23 @@
  *
  */
 public class HttpDotGraphMessageHandler implements HttpRequestHandler  {
-	
+
 	private static final String TEMP_PATH = "/tmp/graph.";
-	
+
 	// 3 supported types
 	private static final String GRAPH_TYPE_PNG = "png";
 	private static final String GRAPH_TYPE_PDF = "pdf";
 	private static final String GRAPH_TYPE_SVG = "svg";
-	
+
 	private static final String CONTENT_TYPE_PNG = "image/png";
 	private static final String CONTENT_TYPE_PDF = "application/pdf";
-
+	private static final String CONTENT_TYPE_SVG = "application/svg+xml";
+
 	private static final Logger log = Logger.getLogger(HttpDotGraphMessageHandler.class.getName());
 
 
 	/**
-	 * 
+	 *
 	 * @param url
 	 * @param proxyUser
 	 * @param proxyPass
@@ -60,17 +61,17 @@ public void handle(
 			final HttpContext context) throws HttpException, IOException {
 
 		String method = request.getRequestLine().getMethod().toUpperCase(Locale.ENGLISH);
-		
+
 		if (!method.equals("GET") && !method.equals("HEAD") && !method.equals("POST")) {
 			throw new MethodNotSupportedException(method + " method not supported");
 		}
-		
+
 		log.info(request.toString());
-		
+
 		String target = request.getRequestLine().getUri();
 
 		response.setStatusCode(HttpStatus.SC_OK);
-		
+
 		if (request instanceof HttpEntityEnclosingRequest) {
 			HttpEntity entity = ((HttpEntityEnclosingRequest) request).getEntity();
 			byte[] entityContent = EntityUtils.toByteArray(entity);
@@ -81,7 +82,7 @@ public void handle(
 			// only respond if we have a valid dot
 			if(StringUtils.isNotBlank(dot) && GraphViz.isValidDotText(dot)) {
 
-				target = (StringUtils.isNotBlank(target) ? 
+				target = (StringUtils.isNotBlank(target) ?
 						StringUtils.remove((URLDecoder.decode(target, "UTF-8")).trim().toLowerCase(), '/') : null);
 
 				log.info("requesting graph type: " + target);
@@ -94,32 +95,33 @@ public void handle(
 		}
 
 		log.info("Responded with Success");
-		
+
 	}
-	
+
 	/**
-	 * 
+	 *
 	 * @param dot
 	 * @return
 	 */
 	private HttpEntity generateGraph(String dot, String target) {
-	
+
 		GraphViz gv = new GraphViz();
 		gv.readString(dot);
 		log.info(gv.getDotSource());
-		
+
 		ContentType contentType;
 		String graphType;
-		
+
 		if(GRAPH_TYPE_SVG.equals(target)) {
-			
+
 			graphType = GRAPH_TYPE_SVG;
-			contentType = ContentType.APPLICATION_SVG_XML;
-
+			// contentType = ContentType.APPLICATION_SVG_XML;
+			contentType = ContentType.create(CONTENT_TYPE_SVG, (Charset) null);
+
 		} else if(GRAPH_TYPE_PDF.equals(target)) {
 			graphType = GRAPH_TYPE_PDF;
 			contentType = ContentType.create(CONTENT_TYPE_PDF, (Charset) null);
-			
+
 		} else {
 			// default png
 			graphType = GRAPH_TYPE_PNG;
@@ -136,11 +138,12 @@ private HttpEntity generateGraph(String dot, String target) {
 		File out = new File(TEMP_PATH + graphType);   // Linux
 
 		gv.writeGraphToFile( gv.getGraph( gv.getDotSource(), graphType ), out );
-		
+
 		FileEntity body = new FileEntity(out, contentType);
-
+		//FileEntity body = new FileEntity(out, "application/svg+xml; charset=utf-8");
+
 		return body;
-       
+
 	}
 
 }

src/info/dawelbeit/graphviz/dot/test/RegExample01.java

@@ -0,0 +1,25 @@
+package info.dawelbeit.graphviz.dot.test;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class RegExample01 {
+
+	public static void main(String[] args) {
+        String data = "digraph travle_schedule { ...";
+
+        // "digraph"과 "{" 사이에 있는 모든 문자를 찾는 정규 표현식 패턴
+        String patternString = "digraph(.*?)\\{";
+
+        Pattern pattern = Pattern.compile(patternString, Pattern.DOTALL);
+        Matcher matcher = pattern.matcher(data);
+
+        if (matcher.find()) {
+            System.out.println("Found: " + matcher.group(1).trim());
+        } else {
+            System.out.println("Not Found");
+        }
+
+	}
+
+}

src/info/dawelbeit/graphviz/dot/test/RegExample02.java

@@ -0,0 +1,22 @@
+package info.dawelbeit.graphviz.dot.test;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class RegExample02 {
+    public static void main(String[] args) {
+        String data = "digraph      travle_schedule      { ...";
+
+        // "digraph" 다음에 오는 단어를 찾는 정규 표현식 패턴
+        String patternString = "digraph\\s+(\\w+)\\s*\\{";
+
+        Pattern pattern = Pattern.compile(patternString);
+        Matcher matcher = pattern.matcher(data);
+
+        if (matcher.find()) {
+            System.out.println("Found: " + matcher.group(1));
+        } else {
+            System.out.println("Not Found");
+        }
+    }
+}