在jsp中调用静态变量

我们首先定义一个用来取得静态变量的Map,重写了Get方法 

/**
 * 功能描述:
 * 相关配置文件:
 * @author nofeng
 */
package com.cnhuike.util;

import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.Map;

import org.apache.commons.lang.StringUtils;


public class ConstantUtil extends HashMap implements Map{

    public ConstantUtil(){

    }

    public Object getValue(String constantPath)throws Exception{
        String classPath=StringUtils.substringBeforeLast(constantPath, ".");
        String fieldName=StringUtils.substringAfterLast(constantPath, ".");
        Field field=Class.forName(classPath).getField(fieldName);
        return field.get( null );
    }


    @Override
    public Object get( Object key ) {
        try {
            return getValue( key.toString() );
        }
        catch (Exception e) {
            throw new IllegalArgumentException( " 找不到相关的变量: " + e.getMessage()

);
        }
    }
}

如何在jsp中调用: 

<jsp:useBean id="constantUtil" class="com.cnhuike.util.ConstantUtil"></jsp:useBean>
${constantUtil['com.cnhuike.util.constant.UserConstant.ISADMIN']}