Get Annotation Parameter : Annotation « Reflection « Java

1. Java
2. Reflection
3. Annotation

Get Annotation Parameter

  
// $Id: ReflectionHelper.java 16271 2009-04-07 20:20:12Z hardy.ferentschik $
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* full listing of individual contributors.
*
* 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
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import java.beans.Introspector;
import java.lang.annotation.Annotation;
import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Member;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.WildcardType;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.Map;


/**
 * Some reflection utility methods.
 *
 * @author Hardy Ferentschik
 */
public class ReflectionHelper {


  @SuppressWarnings("unchecked")
  public static <T> T getAnnotationParameter(Annotation annotation, String parameterName, Class<T> type) {
    try {
      Method m = annotation.getClass().getMethod( parameterName );
      Object o = m.invoke( annotation );
      if ( o.getClass().getName().equals( type.getName() ) ) {
        return ( T ) o;
      }
      else {
        String msg = "Wrong parameter type. Expected: " + type.getName() + " Actual: " + o.getClass().getName();
        throw new RuntimeException( msg );
      }
    }
    catch ( NoSuchMethodException e ) {
      String msg = "The specified annotation defines no parameter '" + parameterName + "'.";
      throw new RuntimeException( msg, e );
    }
    catch ( IllegalAccessException e ) {
      String msg = "Unable to get '" + parameterName + "' from " + annotation.getClass().getName();
      throw new RuntimeException( msg, e );
    }
    catch ( InvocationTargetException e ) {
      String msg = "Unable to get '" + parameterName + "' from " + annotation.getClass().getName();
      throw new RuntimeException( msg, e );
    }
  }

}

   
    
  

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