volicity 自定义指令 Directive 并获取ApplicationContext

背景说明：在基于spring MVC、volicity的WEB项目中，需要在volicity页面中读取远程配置信息(zookeeper)。

第一步：编写读取远程配置信息工具类(具体不做说明)

详情可参阅：http://timerbin.iteye.com/blog/2252372

第二步：编写自定义指令(Directive)

package cn.timerbin.util;
import java.io.IOException;
import java.io.Writer;
import java.text.SimpleDateFormat;
import java.util.Date;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.velocity.context.InternalContextAdapter;
import org.apache.velocity.exception.MethodInvocationException;
import org.apache.velocity.exception.ParseErrorException;
import org.apache.velocity.exception.ResourceNotFoundException;
import org.apache.velocity.runtime.directive.Directive;
import org.apache.velocity.runtime.parser.node.ASTBlock;
import org.apache.velocity.runtime.parser.node.Node;
import org.apache.velocity.runtime.parser.node.SimpleNode;
import com.sun.el.parser.AstString;public class ConfigTool extends Directive {private static final Log logger = LogFactory.getLog(ConfigTool.class);private static final String  MACRO_TAG_NAME="config";private static final int MACRO_TAG_TYPE = 2;//在spring上下文中获取依赖BEANprivate static ZookeeperUtil zookeeperUtil =  (ZookeeperUtil) ApplicationContextUtil.getApplicationContext().getBean(ZookeeperUtil.class);private SimpleNode simpleNode = null;private  String defauleValue="timerBin";@Overridepublic boolean render(InternalContextAdapter context, Writer writer, Node node) throws IOException, ResourceNotFoundException, ParseErrorException, MethodInvocationException {String value = null;for(int i=0,j=node.jjtGetNumChildren();i<j;++i){simpleNode = (SimpleNode)node.jjtGetChild(i);if (null == simpleNode){continue;}if(i == 0){value = getValue((String)simpleNode.value(context));}}if(StringUtils.isBlank(value)){value = defauleValue;}writer.write(value);return false;}//在zookeeper中读取其中的值private String getValue(String key) {String value = null;try {if (!StringUtils.isBlank(key) && null != zookeeperUtil) {value = zookeeperUtil.get(key);if (StringUtils.isBlank(value)) {value = defauleValue;}}else{value = defauleValue;}} catch (Exception e) {value = defauleValue;logger.error(String.format("get.value.is.error:%s", key), e);}return value;}/*** 指定指令的名称*/@Overridepublic String getName() {return MACRO_TAG_NAME;}/*** 当前有LINE 1,BLOCK 2两个值，line行指令，不要end结束符，block块指令，需要end结束符  */@Overridepublic int getType() {return MACRO_TAG_TYPE;}
}

第三步：定义获取spring 上下文 applicationContext的工具类

package cn.timerbin.util;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;public class ApplicationContextUtil implements ApplicationContextAware {private static ApplicationContext context;public void setApplicationContext(ApplicationContext context)throws BeansException {this.context=context;}public static ApplicationContext getApplicationContext(){return context;}
}

第四步：将自定义指令和自定义applicationConext的工具类定义到spring配置文件中

<bean class="cn.timerbin.util.ApplicationContextUtil"></bean><!--volicity-->
<bean id="velocityConfigurer" class="org.springframework.web.servlet.view.velocity.VelocityConfigurer"><property name="resourceLoaderPath" value="/"/><property name="configLocation" value="classpath:velocity.properties"/><property name="velocityProperties"><props><prop key="userdirective">cn.timerbin.util.ConfigTool</prop></props></property>
</bean>

 其中velocityConfigurer常用的配置如下所示：

resourceLoaderPath：页面所放路径

configLocation：模板的配置参数信息其实与velocityProperties可以二选一来定义

velocityProperties

---userdirective：自定义指令

----velocimacro.library：定义宏的绑定仓库地址

其中配置较多可参阅：http://biz.163.com/0000/05/0226/15/1DHBTUKK000017JV.html

第五步：在volicity的页面VM中使用自定义指令

#config("zookeeper-key-name")

当然自定义指令中可以传输多个值。

注：以上配置只是提供了简单的思路，望各位在应用到自己项目中时请自行考虑安全问题(推荐签名方式传值)。