javax.servlet.jsp.JspTagException: Don't know how to iterate over supplied "items" in <forEach&gt-优快云博客

本文链接：https://blog.youkuaiyun.com/u011329762/article/details/24547133

本文介绍了如何处理javax.servlet.jsp.JspTagException，特别是当错误提示'Don't know how to iterate over supplied "items" in <forEach>'时。问题出现在尝试使用<forEach>标签迭代一个无法识别的集合。解决方法是确保根据ID获取的是单行信息，因此不需要使用<c:forEach>标签。正确的代码示例给出了避免该异常的方法。

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错误信息：


SEVERE: Servlet.service() for servlet jsp threw exception
javax.servlet.jsp.JspTagException: Don't know how to iterate over supplied "items" in &lt;forEach&gt;
	at org.apache.taglibs.standard.tag.common.core.ForEachSupport.toForEachIterator(ForEachSupport.java:255)
	at org.apache.taglibs.standard.tag.common.core.ForEachSupport.supportedTypeForEachIterator(ForEachSupport.java:219)
	at org.apache.taglibs.standard.tag.common.core.ForEachSupport.prepare(ForEachSupport.java:137)
	at javax.servlet.jsp.jstl.core.LoopTagSupport.doStartTag(LoopTagSupport.java:227)
	at org.apache.jsp.user.aboutDetail_jsp._jspx_meth_c_005fforEach_005f1(aboutDetail_jsp.java:492)
	at org.apache.jsp.user.aboutDetail_jsp._jspService(aboutDetail_jsp.java:380)
	at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
	at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
	at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
	at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
	at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:748)
	at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:486)
	at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:411)
	at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:338)
	at cn.qidian.servlet.ViewHeaderServlet.doGet(ViewHeaderServlet.java:122)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:620)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)