content: package act.plugin;
  
  /*-
   * #%L
   * ACT Framework
   * %%
   * Copyright (C) 2014 - 2018 ActFramework
   * %%
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   * 
   *      http://www.apache.org/licenses/LICENSE-2.0
   * 
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   * #L%
   */
  
  import act.app.ActionContext;
  
  import javax.inject.Provider;
  
  /**
   * Provide the current user principal name.
   */
  public interface PrincipalProvider extends Provider<String> {
  
      /**
       * The default implementation of {@link PrincipalProvider}.
       *
       * It fetch the principal name from {@link ActionContext#username()}
       */
      class DefaultPrincipalProvider implements PrincipalProvider {
  
          public static final PrincipalProvider INSTANCE = new DefaultPrincipalProvider();
  
          private DefaultPrincipalProvider() {}
  
          @Override
          public String get() {
              ActionContext context = ActionContext.current();
              return null == context ? null : context.username();
          }
      }
  }
  