preparing message store

src/main/java/de/srsoftware/widerhall/Util.java

@@ -4,9 +4,14 @@ import de.srsoftware.tools.translations.Translation;
 import de.srsoftware.widerhall.data.MailingList;
 import de.srsoftware.widerhall.data.User;
 
+import javax.mail.Message;
+import javax.mail.MessagingException;
+import javax.mail.Multipart;
+import javax.mail.Part;
 import javax.mail.internet.AddressException;
 import javax.mail.internet.InternetAddress;
 import javax.servlet.http.HttpServletRequest;
+import java.io.IOException;
 import java.net.URLEncoder;
 import java.nio.charset.StandardCharsets;
 import java.security.MessageDigest;
@@ -118,4 +123,39 @@ public class Util {
     public static boolean getCheckbox(HttpServletRequest req, String key) {
         return "on".equals(req.getParameter(key));
     }
+
+    /**
+     * Return the primary text content of the message.
+     */
+    public static String getText(Part p) throws MessagingException, IOException {
+        // https://javaee.github.io/javamail/FAQ
+        if (p.isMimeType("text/*")) return (String)p.getContent();
+
+        if (p.isMimeType("multipart/alternative")) {
+            // prefer html text over plain text
+            Multipart mp = (Multipart)p.getContent();
+            String text = null;
+            for (int i = 0; i < mp.getCount(); i++) {
+                Part bp = mp.getBodyPart(i);
+                if (bp.isMimeType("text/plain")) {
+                    if (text == null) text = getText(bp);
+                    continue;
+                } else if (bp.isMimeType("text/html")) {
+                    String s = getText(bp);
+                    if (s != null) return s;
+                } else {
+                    return getText(bp);
+                }
+            }
+            return text;
+        } else if (p.isMimeType("multipart/*")) {
+            Multipart mp = (Multipart)p.getContent();
+            for (int i = 0; i < mp.getCount(); i++) {
+                String s = getText(mp.getBodyPart(i));
+                if (s != null) return s;
+            }
+        }
+
+        return null;
+    }
 }