import org.springframework.context.expression.EnvironmentAccessor; //导入依赖的package包/类
/**
 * Gets spring expression parser.
 *
 * @return the spring expression parser
 */
protected SpringELExpressionParser getSpringExpressionParser() {
    final SpelParserConfiguration configuration = new SpelParserConfiguration();
    final SpelExpressionParser spelExpressionParser = new SpelExpressionParser(configuration);
    final SpringELExpressionParser parser = new SpringELExpressionParser(spelExpressionParser,
            this.flowBuilderServices.getConversionService());

    parser.addPropertyAccessor(new ActionPropertyAccessor());
    parser.addPropertyAccessor(new BeanFactoryPropertyAccessor());
    parser.addPropertyAccessor(new FlowVariablePropertyAccessor());
    parser.addPropertyAccessor(new MapAdaptablePropertyAccessor());
    parser.addPropertyAccessor(new MessageSourcePropertyAccessor());
    parser.addPropertyAccessor(new ScopeSearchingPropertyAccessor());
    parser.addPropertyAccessor(new BeanExpressionContextAccessor());
    parser.addPropertyAccessor(new MapAccessor());
    parser.addPropertyAccessor(new MapAdaptablePropertyAccessor());
    parser.addPropertyAccessor(new EnvironmentAccessor());
    parser.addPropertyAccessor(new ReflectivePropertyAccessor());
    return parser;

}
 

import org.springframework.context.expression.EnvironmentAccessor; //导入依赖的package包/类
private EvaluationContext createEvaluationContext(PageContext pageContext) {
	StandardEvaluationContext context = new StandardEvaluationContext();
	context.addPropertyAccessor(new JspPropertyAccessor(pageContext));
	context.addPropertyAccessor(new MapAccessor());
	context.addPropertyAccessor(new EnvironmentAccessor());
	context.setBeanResolver(new BeanFactoryResolver(getRequestContext().getWebApplicationContext()));
	ConversionService conversionService = getConversionService(pageContext);
	if (conversionService != null) {
		context.setTypeConverter(new StandardTypeConverter(conversionService));
	}
	return context;
}
 

import org.springframework.context.expression.EnvironmentAccessor; //导入依赖的package包/类
public ConsumerBeanAutoConfiguration() {
	this.expressionParser = new SpelExpressionParser();

	this.expressionPropertyAccessors = new ArrayList<PropertyAccessor>();
	this.expressionPropertyAccessors.add(new EnvironmentAccessor());
	this.expressionPropertyAccessors.add(new BeanFactoryAccessor());
	this.expressionPropertyAccessors.add(new ReflectivePropertyAccessor());
	this.expressionPropertyAccessors.add(new DirectFieldAccessPropertyAccessor());
}
 

import org.springframework.context.expression.EnvironmentAccessor; //导入依赖的package包/类
public ElementConfiguration parseProperty(Object value)
{
    LOGGER.debug("value : " + value);
    if (value instanceof TypedStringValue)
    {
        TypedStringValue stringValue = (TypedStringValue) value;
        if (stringValue.getTargetTypeName() != null)
        {
            return getEnumObjectConfiguration(stringValue);
        }
        else
        {
            PrimitiveConfiguration primitiveConfiguration = objectConfigurationFactory
                    .createPrimitiveConfiguration();
            if (useSPEL(stringValue))
            {
                ExpressionParser parser = new SpelExpressionParser();
                String expAsStringWithToken = stringValue.getValue().trim();
                String expAsString = expAsStringWithToken.substring(2, expAsStringWithToken.length() - 1).trim();
                LOGGER.trace("This property is a SPEL expression: " + expAsString);

                // String regex = "systemProperties\\['([^\\s]+)'\\]";

                Expression exp = parser.parseExpression(expAsString);
                StandardEvaluationContext sec = null;
                if (sec == null)
                {
                    sec = new StandardEvaluationContext();
                    sec.addPropertyAccessor(new EnvironmentAccessor());
                    sec.addPropertyAccessor(new BeanExpressionContextAccessor());
                    sec.addPropertyAccessor(new BeanFactoryAccessor());
                    sec.addPropertyAccessor(new MapAccessor());
                }
                primitiveConfiguration.setValue(String.valueOf(exp.getValue()));
            }
            else
            {
                LOGGER.trace("This property is NOT a SPEL expression: " + stringValue.getValue());
                primitiveConfiguration.setValue(stringValue.getValue());
            }
            return primitiveConfiguration;
        }
    }
    else if (value instanceof RuntimeBeanReference)
    {
        RuntimeBeanReference beanReference = (RuntimeBeanReference) value;
        ReferenceConfiguration referenceConfiguration = objectConfigurationFactory.createReferenceConfiguration();
        referenceConfiguration.setReferenceName(beanReference.getBeanName());
        return referenceConfiguration;
    }
    else if (value instanceof ManagedList<?>)
    {
        return parseValueList((ManagedList<?>) value);
    }
    else if (value instanceof ManagedMap<?, ?>)
    {
        return parseValueMap((ManagedMap<?, ?>) value);
    }
    else if (value instanceof BeanDefinitionHolder)
    {
        BeanDefinitionHolder beanDefinitionHolder = (BeanDefinitionHolder) value;
        return parseBeanDefinition(beanDefinitionHolder.getBeanDefinition());
    }
    else
    {
        throw new UnsupportedOperationException("The type of property value is not suppported : " + value
                + " (class : " + value.getClass().getName() + ")");
    }
}