gcc-4.4.0/libjava/classpath/javax/management/AttributeValueExp.java

/* AttributeValueExp.java -- Represents attributes to be passed to queries.
   Copyright (C) 2007 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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any later version.

GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

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02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
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this exception to your version of the library, but you are not
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package javax.management;

/**
 * Represents an attribute value being used as an argument
 * to a relational constraint.
 *
 * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
 * @since 1.5
 */
public class AttributeValueExp
  implements ValueExp
{

  /**
   * Compatible with JDK 1.5
   */
  private static final long serialVersionUID = -7768025046539163385L;

  /**
   * The name of the attribute.
   */
  private String attr;

  /**
   * Constructs a new {@link AttributeValueExp}.
   *
   * @deprecated An instance created with a <code>null</code>
   *             attribute name can not be used in a query.
   */
  @Deprecated public AttributeValueExp()
  {
  }

  /**
   * Constructs a new {@link AttributeValueExp} using the
   * specified attribute.
   *
   * @param attr the name of the attribute whose value
   *             will be used for this expression.
   */
  public AttributeValueExp(String attr)
  {
    this.attr = attr;
  }

  /**
   * Applies the {@link AttributeValueExp} to the specified
   * management bean by obtaining the attribute value from
   * the {@link MBeanServer} and using it to create a
   * {@link StringValueExp}.
   *
   * @param name the {@link ObjectName} of the bean to obtain
   *             the value from.
   * @return a {@link StringValueExp} containing the result.
   * @throws BadStringOperationException if an invalid string
   *                                     operation is used by
   *                                     the value expression.
   * @throws BadBinaryOpValueExpException if an invalid expression
   *                                      is used by the value expression.
   * @throws BadAttributeValueExpException if an invalid attribute
   *                                       is used by the value expression.
   * @throws InvalidApplicationException if the value expression is applied
   *                                     to the wrong type of bean.
   */
  public ValueExp apply(ObjectName name)
    throws BadStringOperationException, BadBinaryOpValueExpException,
	   BadAttributeValueExpException, InvalidApplicationException
  {
    Object val = getAttribute(name);
    if (val == null || !(val instanceof String))
      throw new BadAttributeValueExpException(val);
    return new StringValueExp((String) val);
  }

  /**
   * Returns the value of the attribute by calling the
   * {@link MBeanServer#getAttribute(ObjectName)} method of
   * the server returned by {@link QueryEval#getMBeanServer()}.
   * If an exception occurs, <code>null</code> is returned.
   *
   * @param name the {@link ObjectName} of the bean to obtain
   *             the value from.
   * @return a {@link StringValueExp} containing the result.
   */
  protected Object getAttribute(ObjectName name)
  {
    try
      {
	return QueryEval.getMBeanServer().getAttribute(name, attr);
      }
    catch (NullPointerException e)
      {
	return null;
      }
    catch (MBeanException e)
      {
	return null;
      }
    catch (AttributeNotFoundException e)
      {
	return null;
      }
    catch (InstanceNotFoundException e)
      {
	return null;
      }
    catch (ReflectionException e)
      {
	return null;
      }
  }

  /**
   * Returns the attribute name.
   *
   * @return the attribute name.
   */
  public String getAttributeName()
  {
    return attr;
  }

  /**
   * Sets the {@link MBeanServer} on which the query
   * will be performed.
   *
   * @param server the new server.
   */
  public void setMBeanServer(MBeanServer server)
  {
    /* This seems to do nothing any more */
  }

  /**
   * Returns the attribute name, quoted.
   *
   * @return the quoted attribute name.
   */
  public String toString()
  {
    return "'" + attr + "'";
  }

}