[REFACTORING] Remove more REGEX usages

protocols/pop3/src/main/java/org/apache/james/protocols/pop3/core/AbstractApopCmdHandler.java

@@ -23,6 +23,7 @@
 
 import javax.inject.Inject;
 
+import org.apache.commons.lang3.StringUtils;
 import org.apache.james.core.Username;
 import org.apache.james.metrics.api.MetricFactory;
 import org.apache.james.protocols.api.ProtocolSession.State;
@@ -58,7 +59,7 @@ public Response onCommand(POP3Session session, Request request) {
         String[] parts = null;
         boolean syntaxError = false;
         if (parameters != null) {
-            parts = parameters.split(" ");
+            parts = StringUtils.split(parameters, " ");
             if (parts.length != 2) {
                 syntaxError = true;
             }

protocols/smtp/src/main/java/org/apache/james/protocols/smtp/SMTPResponse.java

@@ -22,6 +22,7 @@
 import java.util.ArrayList;
 import java.util.List;
 
+import org.apache.commons.lang3.StringUtils;
 import org.apache.james.protocols.api.AbstractResponse;
 
 /**
@@ -56,7 +57,7 @@ public SMTPResponse(String rawLine) {
 
 
     private  static String extractCode(String raw) {
-        String[] args = raw.split(" ");
+        String[] args = StringUtils.split(raw, " ");
         if (args != null && args.length > 1) {
             return args[0];
 
@@ -66,7 +67,7 @@ private  static String extractCode(String raw) {
     }
 
     private  static String extractResponse(String raw) {
-        String[] args = raw.split(" ");
+        String[] args = StringUtils.split(raw, " ");
         if (args != null && args.length > 1) {
             return args[2];
 

protocols/smtp/src/main/java/org/apache/james/protocols/smtp/core/esmtp/AuthCmdHandler.java

@@ -32,7 +32,6 @@
 import java.util.Locale;
 import java.util.Optional;
 import java.util.StringTokenizer;
-import java.util.regex.Pattern;
 
 import org.apache.commons.lang3.StringUtils;
 import org.apache.james.core.Username;
@@ -82,7 +81,6 @@ public class AuthCmdHandler
     private static final Response AUTH_READY_PASSWORD_LOGIN = new SMTPResponse(SMTPRetCode.AUTH_READY, "UGFzc3dvcmQ6").immutable(); // base64 encoded "Password:
     private static final Response AUTH_FAILED = new SMTPResponse(SMTPRetCode.AUTH_FAILED, "Authentication Failed").immutable();
     private static final Response UNKNOWN_AUTH_TYPE = new SMTPResponse(SMTPRetCode.PARAMETER_NOT_IMPLEMENTED, "Unrecognized Authentication Type").immutable();
-    public static final Pattern LINE_BREAK_PATTERN = Pattern.compile("\r\n");
 
     private abstract static class AbstractSMTPLineHandler implements LineHandler<SMTPSession> {
 

server/container/guice/configuration/src/main/java/org/apache/james/utils/DelegatedPropertiesConfiguration.java

@@ -44,10 +44,10 @@
 
 public class DelegatedPropertiesConfiguration implements Configuration {
 
-    private final String delimiter;
+    private final char delimiter;
     private final Configuration configuration;
 
-    DelegatedPropertiesConfiguration(String delimiter, Configuration configuration) {
+    DelegatedPropertiesConfiguration(char delimiter, Configuration configuration) {
         this.delimiter = delimiter;
         this.configuration = configuration;
     }
@@ -378,7 +378,7 @@ private Stream<String> splitAndStripDoubleQuotes(String value) {
         return Optional.ofNullable(value)
             .filter(s -> !StringUtils.isAllBlank(s))
             .map(notNullValue -> Stream
-                .of(StringUtils.strip(notNullValue, "\"").split(delimiter))
+                .of(StringUtils.split(StringUtils.strip(notNullValue, "\""), delimiter))
                 .map(String::trim)
                 .filter(s -> !StringUtils.isAllBlank(s)))
             .orElseGet(Stream::empty);

server/container/guice/configuration/src/main/java/org/apache/james/utils/PropertiesProvider.java

@@ -48,7 +48,6 @@ public class PropertiesProvider {
 
     private static final Logger LOGGER = LoggerFactory.getLogger("org.apache.james.CONFIGURATION");
     private static final char COMMA = ',';
-    private static final String COMMA_STRING = ",";
 
     @VisibleForTesting
     public static PropertiesProvider forTesting() {
@@ -96,7 +95,7 @@ private Configuration getConfiguration(File propertiesFile) throws Configuration
                 .setListDelimiterHandler(new DefaultListDelimiterHandler(COMMA))
                 .setFile(propertiesFile));
 
-        return new DelegatedPropertiesConfiguration(COMMA_STRING, builder.getConfiguration());
+        return new DelegatedPropertiesConfiguration(COMMA, builder.getConfiguration());
     }
 
     private Optional<File> getConfigurationFile(String fileName) {

server/mailet/mock-smtp-server/src/main/java/org/apache/james/mock/smtp/server/ExtendedMailFromCommand.java

@@ -29,7 +29,12 @@
 import org.subethamail.smtp.server.Session;
 import org.subethamail.smtp.util.EmailUtils;
 
+import com.google.common.base.CharMatcher;
+
 public class ExtendedMailFromCommand extends BaseCommand {
+
+    public static final CharMatcher NUMBER_MATCHER = CharMatcher.inRange('0', '9');
+
     public ExtendedMailFromCommand() {
         super("MAIL", "Specifies the sender.", "FROM: <sender> [ <parameters> ]");
     }
@@ -56,7 +61,7 @@ public void execute(String commandString, Session sess) throws IOException, Drop
                 int sizec = largs.indexOf(" size=");
                 if (sizec > -1) {
                     String ssize = largs.substring(sizec + 6).trim();
-                    if (ssize.length() > 0 && ssize.matches("[0-9]+")) {
+                    if (ssize.length() > 0 && NUMBER_MATCHER.matchesAllOf(ssize)) {
                         size = Integer.parseInt(ssize);
                     }
                 }

server/protocols/jmap-draft/src/main/java/org/apache/james/jmap/draft/model/CreationMessage.java

@@ -433,8 +433,14 @@ public boolean hasValidEmail() {
         }
 
         public EmailUserAndDomain getEmailUserAndDomain() {
-            String[] splitAddress = email.get().split("@", 2);
-            return new EmailUserAndDomain(Optional.ofNullable(splitAddress[0]), Optional.ofNullable(splitAddress[1]));
+            int atIndex = email.get().indexOf('@');
+            if (atIndex < 0 || atIndex == email.get().length() - 1) {
+                return new EmailUserAndDomain(Optional.of(email.get()), Optional.empty());
+            }
+            String user = email.get().substring(0, atIndex);
+            String domain = email.get().substring(atIndex + 1);
+
+            return new EmailUserAndDomain(Optional.of(user), Optional.of(domain));
         }
 
         @Override

server/protocols/jmap-rfc-8621/src/main/scala/org/apache/james/jmap/routes/DownloadRoutes.scala

@@ -183,7 +183,7 @@ class AttachmentBlobResolver @Inject()(val attachmentManager: AttachmentManager)
 class MessagePartBlobResolver @Inject()(val messageIdFactory: MessageId.Factory,
                                         val messageIdManager: MessageIdManager) extends BlobResolver {
   private def asMessageAndPartId(blobId: BlobId): Try[(MessageId, PartId)] = {
-    blobId.value.value.split("_").toList match {
+    blobId.value.value.split('_').toList match {
       case List(messageIdString, partIdString) => for {
         messageId <- Try(messageIdFactory.fromString(messageIdString))
         partId <- PartId.parse(partIdString)

server/protocols/jmap-rfc-8621/src/main/scala/org/apache/james/jmap/routes/EventSourceRoutes.scala

@@ -70,7 +70,7 @@ case class EventSourceOptionsFactory @Inject() (typeStateFactory: TypeStateFacto
     queryParam(request, "types") match {
       case None => Left(new IllegalArgumentException("types parameter is compulsory"))
       case Some(List("*")) => Right(typeStateFactory.all.toSet)
-      case Some(list) => list.flatMap(_.split(","))
+      case Some(list) => list.flatMap(_.split(','))
         .map(string => typeStateFactory.parse(string))
         .sequence.map(_.toSet)
     }

server/protocols/protocols-library/src/main/java/org/apache/james/protocols/lib/netty/AbstractConfigurableAsyncServer.java

@@ -40,6 +40,7 @@
 import org.apache.commons.configuration2.HierarchicalConfiguration;
 import org.apache.commons.configuration2.ex.ConfigurationException;
 import org.apache.commons.configuration2.tree.ImmutableNode;
+import org.apache.commons.lang3.StringUtils;
 import org.apache.james.filesystem.api.FileSystem;
 import org.apache.james.lifecycle.api.Configurable;
 import org.apache.james.protocols.api.Encryption;
@@ -165,10 +166,10 @@ public final void configure(HierarchicalConfiguration<ImmutableNode> config) thr
             return;
         }
 
-        String[] listen = config.getString("bind", "0.0.0.0:" + getDefaultPort()).split(",");
+        String[] listen = StringUtils.split(config.getString("bind", "0.0.0.0:" + getDefaultPort()), ',');
         List<InetSocketAddress> bindAddresses = new ArrayList<>();
         for (String aListen : listen) {
-            String[] bind = aListen.split(":");
+            String[] bind = StringUtils.split(aListen, ':');
 
             InetSocketAddress address;
             String ip = bind[0].trim();