add servlet to encode and decode diagrams

.

src/main/java/net/sourceforge/plantuml/servlet/AsciiCoderServlet.java

@@ -0,0 +1,151 @@
+/* ========================================================================
+ * PlantUML : a free UML diagram generator
+ * ========================================================================
+ *
+ * Project Info:  https://plantuml.com
+ *
+ * This file is part of PlantUML.
+ *
+ * PlantUML is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * PlantUML 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 General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
+ * USA.
+ */
+package net.sourceforge.plantuml.servlet;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import jakarta.servlet.ServletException;
+import jakarta.servlet.http.HttpServlet;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import net.sourceforge.plantuml.code.Transcoder;
+import net.sourceforge.plantuml.code.TranscoderUtil;
+import net.sourceforge.plantuml.servlet.utility.UrlDataExtractor;
+
+/**
+ * ASCII encoder and decoder servlet for the webapp.
+ * This servlet encodes the diagram in text format or decodes the compressed diagram string.
+ */
+@SuppressWarnings("SERIAL")
+public class AsciiCoderServlet extends HttpServlet {
+
+    /**
+     * Regex pattern to fetch last part of the URL.
+     */
+    private static final Pattern URL_PATTERN = Pattern.compile("^.*[^a-zA-Z0-9\\-\\_]([a-zA-Z0-9\\-\\_]+)");
+
+    /**
+     * Context path from the servlet mapping URL pattern.
+     *
+     * @return servlet context path without leading or tailing slash
+     */
+    protected String getServletContextPath() {
+        return "coder";
+    }
+
+    @Override
+    public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
+        request.setCharacterEncoding("UTF-8");
+
+        final String encodedText = getEncodedTextFromUrl(request);
+
+        String text = "";
+        try {
+            text = getTranscoder().decode(encodedText);
+        } catch (Exception e) {
+            response.setStatus(500);
+            e.printStackTrace();
+        }
+
+        response.addHeader("Access-Control-Allow-Origin", "*");
+        response.setContentType("text/plain;charset=UTF-8");
+        response.getWriter().write(text);
+    }
+
+    @Override
+    protected void doPost(
+        HttpServletRequest request,
+        HttpServletResponse response
+    ) throws ServletException, IOException {
+        request.setCharacterEncoding("UTF-8");
+
+        // read textual diagram source from request body
+        final StringBuilder uml = new StringBuilder();
+        try (BufferedReader in = request.getReader()) {
+            String line;
+            while ((line = in.readLine()) != null) {
+                uml.append(line).append('\n');
+            }
+        }
+
+        // encode textual diagram source
+        String encoded = "";
+        try {
+            encoded = getTranscoder().encode(uml.toString());
+        } catch (Exception e) {
+            response.setStatus(500);
+            e.printStackTrace();
+        }
+
+        response.addHeader("Access-Control-Allow-Origin", "*");
+        response.setContentType("text/plain;charset=UTF-8");
+        response.getWriter().write(encoded);
+    }
+
+    /**
+     * Get PlantUML transcoder.
+     *
+     * @return transcoder instance
+     */
+    protected Transcoder getTranscoder() {
+        return TranscoderUtil.getDefaultTranscoder();
+    }
+
+    /**
+     * Get encoded textual diagram source from URL.
+     *
+     * @param request http request which contains the source URL
+     *
+     * @return if successful encoded textual diagram source from URL; otherwise empty string
+     *
+     * @throws IOException if an input or output exception occurred
+     */
+    protected String getEncodedTextFromUrl(HttpServletRequest request) throws IOException {
+        // textual diagram source from request URI
+        String url = request.getRequestURI();
+        final String contextpath = "/" + getServletContextPath() + "/";
+        if (url.contains(contextpath) && !url.endsWith(contextpath)) {
+            final String encoded = UrlDataExtractor.getEncodedDiagram(request.getRequestURI(), "");
+            if (!encoded.isEmpty()) {
+                return encoded;
+            }
+        }
+        // textual diagram source from "url" parameter
+        url = request.getParameter("url");
+        if (url != null && !url.trim().isEmpty()) {
+            // Catch the last part of the URL if necessary
+            final Matcher matcher = URL_PATTERN.matcher(url);
+            if (matcher.find()) {
+                url = matcher.group(1);
+            }
+            return url;
+        }
+        // nothing found
+        return "";
+    }
+
+}

src/main/java/net/sourceforge/plantuml/servlet/PlantUmlServlet.java

@@ -27,21 +27,15 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.net.HttpURLConnection;
 import java.net.URL;
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
-
 import javax.net.ssl.HttpsURLConnection;
 
 import jakarta.servlet.RequestDispatcher;
 import jakarta.servlet.ServletException;
-import jakarta.servlet.http.HttpServlet;
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
 
 import net.sourceforge.plantuml.OptionFlags;
 import net.sourceforge.plantuml.api.PlantumlUtils;
-import net.sourceforge.plantuml.code.Transcoder;
-import net.sourceforge.plantuml.code.TranscoderUtil;
 import net.sourceforge.plantuml.png.MetadataTag;
 import net.sourceforge.plantuml.servlet.utility.Configuration;
 import net.sourceforge.plantuml.servlet.utility.UmlExtractor;
@@ -58,7 +52,7 @@ import net.sourceforge.plantuml.servlet.utility.UrlDataExtractor;
  * Modified by Maxime Sinclair
  */
 @SuppressWarnings("SERIAL")
-public class PlantUmlServlet extends HttpServlet {
+public class PlantUmlServlet extends AsciiCoderServlet {
 
     /**
      * Default encoded uml text.
@@ -66,10 +60,10 @@ public class PlantUmlServlet extends HttpServlet {
      */
     private static final String DEFAULT_ENCODED_TEXT = "SyfFKj2rKt3CoKnELR1Io4ZDoSa70000";
 
-    /**
-     * Regex pattern to fetch last part of the URL.
-     */
-    private static final Pattern URL_PATTERN = Pattern.compile("^.*[^a-zA-Z0-9\\-\\_]([a-zA-Z0-9\\-\\_]+)");
+    @Override
+    protected String getServletContextPath() {
+        return "uml";
+    }
 
     static {
         OptionFlags.ALLOW_INCLUDE = false;
@@ -78,11 +72,19 @@ public class PlantUmlServlet extends HttpServlet {
         }
     }
 
+    /**
+     * Encode arbitrary string to HTML string.
+     *
+     * @param string arbitrary string
+     *
+     * @return html encoded string
+     */
     public static String stringToHTMLString(String string) {
-        final StringBuffer sb = new StringBuffer(string.length());
+        final StringBuilder sb = new StringBuilder(string.length());
         // true if last char was blank
         final int length = string.length();
-        for (int offset = 0; offset < length;) {
+        int offset = 0;
+        while (offset < length) {
             final int c = string.codePointAt(offset);
             if (c == ' ') {
                 sb.append(' ');
@@ -115,7 +117,6 @@ public class PlantUmlServlet extends HttpServlet {
         return sb.toString();
     }
 
-
     @Override
     public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
         request.setCharacterEncoding("UTF-8");
@@ -215,26 +216,7 @@ public class PlantUmlServlet extends HttpServlet {
      * @throws IOException if an input or output exception occurred
      */
     private String getTextFromUrl(HttpServletRequest request) throws IOException {
-        // textual diagram source from request URI
-        String url = request.getRequestURI();
-        if (url.contains("/uml/") && !url.endsWith("/uml/")) {
-            final String encoded = UrlDataExtractor.getEncodedDiagram(request.getRequestURI(), "");
-            if (!encoded.isEmpty()) {
-                return getTranscoder().decode(encoded);
-            }
-        }
-        // textual diagram source from "url" parameter
-        url = request.getParameter("url");
-        if (url != null && !url.trim().isEmpty()) {
-            // Catch the last part of the URL if necessary
-            final Matcher matcher = URL_PATTERN.matcher(url);
-            if (matcher.find()) {
-                url = matcher.group(1);
-            }
-            return getTranscoder().decode(url);
-        }
-        // nothing found
-        return "";
+        return getTranscoder().decode(getEncodedTextFromUrl(request));
     }
 
     /**
@@ -318,15 +300,6 @@ public class PlantUmlServlet extends HttpServlet {
         response.sendRedirect(path);
     }
 
-    /**
-     * Get PlantUML transcoder.
-     *
-     * @return transcoder instance
-     */
-    private Transcoder getTranscoder() {
-        return TranscoderUtil.getDefaultTranscoder();
-    }
-
     /**
      * Get open http connection from URL.
      *
@@ -341,7 +314,6 @@ public class PlantUmlServlet extends HttpServlet {
             HttpsURLConnection con = (HttpsURLConnection) url.openConnection();
             con.setRequestMethod("GET");
             con.setReadTimeout(10000); // 10 seconds
-            // printHttpsCert(con);
             con.connect();
             return con;
         } else {

src/main/webapp/WEB-INF/web.xml

@@ -201,6 +201,15 @@
     <url-pattern>/language</url-pattern>
   </servlet-mapping>
 
+  <servlet>
+    <servlet-name>asciicoder</servlet-name>
+    <servlet-class>net.sourceforge.plantuml.servlet.AsciiCoderServlet</servlet-class>
+  </servlet>
+  <servlet-mapping>
+    <servlet-name>asciicoder</servlet-name>
+    <url-pattern>/coder/*</url-pattern>
+  </servlet-mapping>
+
 
   <!-- ========================================================== -->
   <!-- Error Handler -->