add servlet to encode and decode diagrams

.

src/test/java/net/sourceforge/plantuml/servlet/TestAsciiCoder.java

@@ -0,0 +1,61 @@
+package net.sourceforge.plantuml.servlet;
+
+import java.io.IOException;
+import java.io.OutputStreamWriter;
+import java.net.HttpURLConnection;
+import java.net.URL;
+import java.net.URLConnection;
+
+
+public class TestAsciiCoder extends WebappTestCase {
+
+    /**
+     * Verifies the decoding for the Bob -> Alice sample
+     */
+    public void testBobAliceSampleDiagramDecoding() throws IOException {
+        final URL url = new URL(getServerUrl() + "/coder/" + TestUtils.SEQBOB);
+        final URLConnection conn = url.openConnection();
+        // Analyze response
+        // Verifies the Content-Type header
+        assertEquals(
+            "Response content type is not TEXT PLAIN or UTF-8",
+            "text/plain;charset=utf-8",
+            conn.getContentType().toLowerCase()
+        );
+        // Get and verify the content
+        final String diagram = getContentText(conn);
+        assertEquals(TestUtils.SEQBOBCODE, diagram);
+    }
+
+    /**
+     * Verifies the encoding for the Bob -> Alice sample
+     */
+    public void testBobAliceSampleDiagramEncoding() throws IOException {
+        final URL url = new URL(getServerUrl() + "/coder");
+        final HttpURLConnection conn = (HttpURLConnection)url.openConnection();
+        conn.setRequestMethod("POST");
+        conn.setDoOutput(true);
+        conn.setRequestProperty("Content-type", "text/plain");
+        try (final OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream())) {
+            writer.write(TestUtils.SEQBOBCODE);
+            writer.flush();
+        }
+        // Analyze response
+        // HTTP response 200
+        assertEquals(
+            "Bad HTTP status received",
+            200,
+            conn.getResponseCode()
+        );
+        // Verifies the Content-Type header
+        assertEquals(
+            "Response content type is not TEXT PLAIN or UTF-8",
+            "text/plain;charset=utf-8",
+            conn.getContentType().toLowerCase()
+        );
+        // Get the content and verify its size
+        final String diagram = getContentText(conn.getInputStream());
+        assertEquals(TestUtils.SEQBOB, diagram);
+    }
+
+}