校验值对象——应用Visitor模式和反射

public synchronized void validate( AbstractParameter param ) throws AttributeValidatorException
{
      Class clazz = param.getClass();
      Method[] methods = clazz.getMethods();

      //Cycle over all methods and call the getters!
      //Check if the getter result is null.
      //If result is null throw AttributeValidatorException.
      Iterator methodIter = Arrays.asList( methods ).iterator();
      Method method = null;
      String methodName = null;

      while ( methodIter.hasNext() )
      {
            method = (Method) methodIter.next();
            methodName = method.getName();

            if ( methodName.startsWith( "get" ) &&
            clazz.equals( method.getDeclaringClass() ) &&
                 !param.isOptionalMethod( methodName ) )
            {
                 Object methodResult = null;

                 try
                 {
                       methodResult = method.invoke( param, null );
                 }
                 catch ( IllegalArgumentException e )
                 {
                       throw new AttributeValidatorException( e.getMessage() );
                 }
                 catch ( IllegalAccessException e )
                 {
                       throw new AttributeValidatorException( e.getMessage() );
                 }
                 catch ( InvocationTargetException e )
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