Add Default Expiration Option to MapSessionRepository

Fixes gh-73

spring-session/src/main/java/org/springframework/session/MapSessionRepository.java

@@ -33,6 +33,11 @@ import java.util.concurrent.ConcurrentHashMap;
  * @since 1.0
  */
 public class MapSessionRepository implements SessionRepository<ExpiringSession> {
+    /**
+     * If non-null, this value is used to override {@link ExpiringSession#setMaxInactiveInterval(int)}.
+     */
+    private Integer defaultMaxInactiveInterval;
+
     private final Map<String,ExpiringSession> sessions;
 
     /**
@@ -54,6 +59,14 @@ public class MapSessionRepository implements SessionRepository<ExpiringSession>
         this.sessions = sessions;
     }
 
+    /**
+     * If non-null, this value is used to override {@link ExpiringSession#setMaxInactiveInterval(int)}.
+     * @param defaultMaxInactiveInterval
+     */
+    public void setDefaultMaxInactiveInterval(int defaultMaxInactiveInterval) {
+        this.defaultMaxInactiveInterval = Integer.valueOf(defaultMaxInactiveInterval);
+    }
+
     public void save(ExpiringSession session) {
         sessions.put(session.getId(), new MapSession(session));
     }
@@ -77,6 +90,10 @@ public class MapSessionRepository implements SessionRepository<ExpiringSession>
     }
 
     public ExpiringSession createSession() {
-        return new MapSession();
+        ExpiringSession result = new MapSession();
+        if(defaultMaxInactiveInterval != null) {
+            result.setMaxInactiveInterval(defaultMaxInactiveInterval);
+        }
+        return result;
     }
 }

spring-session/src/main/java/org/springframework/session/data/redis/RedisOperationsSessionRepository.java

@@ -148,7 +148,7 @@ public class RedisOperationsSessionRepository implements SessionRepository<Redis
     private final RedisSessionExpirationPolicy expirationPolicy;
 
     /**
-     * If non-null, this value is used to override {@link RedisSession#setDefaultMaxInactiveInterval(int)}.
+     * If non-null, this value is used to override the default value for {@link RedisSession#setMaxInactiveInterval(int)}.
      */
     private Integer defaultMaxInactiveInterval;