The Struts dispatcher cannot be found. This is usually caused by using Struts t-优快云博客

本文链接：https://blog.youkuaiyun.com/itlqi/article/details/42076433

本文探讨了Struts2框架中JSP页面使用Struts标签导致的异常问题，详细分析了错误原因，并提供了在web.xml中配置过滤器的具体解决方案。

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严重: Servlet.service() for servlet jsp threw exception

The Struts dispatcher cannot be found. This is usually caused by using Struts tags without the associated filter. Struts tags are only usable when the request has passed through its servlet filter, which initializes the Struts dispatcher needed for this tag. - [unknown location]

at org.apache.struts2.views.jsp.TagUtils.getStack(TagUtils.java:60)

at org.apache.struts2.views.jsp.StrutsBodyTagSupport.getStack(StrutsBodyTagSupport.java:44)

at org.apache.struts2.views.jsp.ComponentTagSupport.doStartTag(ComponentTagSupport.java:48)

at org.apache.jsp.index_jsp._jspx_meth_s_005faction_005f0(index_jsp.java:128)

at org.apache.jsp.index_jsp._jspService(index_jsp.java:96)

at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:388)

at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)

at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)

at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)

at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:602)

at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)

at java.lang.Thread.run(Thread.java:619)

出现以上错误原因是：

页面上使用struts标签如：

<%@taglib uri="/struts-tags"  prefix="s"%>

  <s:action name="cus_like"  namespace="/" >
  	<s:param name="val" value="123456456"></s:param>
  </s:action>

解决如上在web.xml过滤struts过滤器的时候过滤action 同时也过滤jsp

  <filter>
  	<filter-name>struts2</filter-name>
  	<filter-class>
  		org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter
  	</filter-class>
  </filter>
  <filter-mapping>
  	<filter-name>struts2</filter-name>
  	<url-pattern>*.action</url-pattern>
  </filter-mapping>
  <filter-mapping>
  	<filter-name>struts2</filter-name>
  	<url-pattern>*.jsp</url-pattern>
  </filter-mapping>

后台代码获取<s:param/> 标签传递值

public class CusAction{

	public String val;
	
	public void like(){
		//<s:param ></s:param>是以request方式的值的,而不是以参数传值 
		/*
		 * 用reqeust.getParameter 是无法 取到值得
		 *
		 */
		System.out.println("直接赋值"+val);
		System.out.println("request取值"+ServletActionContext.getRequest().getAttribute("val"));
		
	}
	
}