Using JSTL core lib fails when creating custom tag

问题

So I'm trying to import two taglibs:

<%@ taglib uri="MyCustomTagLib" prefix="myLib" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>

However, I can only use ONE of them or else I get an error (I shortened it, hope that's ok):

WARNING: ApplicationDispatcher[/CSE336_A5] PWC1231: Servlet.service() for servlet jsp threw exception
java.lang.NullPointerException
    at org.apache.jasper.compiler.TagLibraryInfoImpl.toString(TagLibraryInfoImpl.java:129)
    at java.lang.String.valueOf(String.java:2826)
    at java.lang.StringBuilder.append(StringBuilder.java:115)
    at java.util.AbstractMap.toString(AbstractMap.java:490)
    at org.apache.taglibs.standard.tag.common.core.OutSupport.out(OutSupport.java:211)
    at org.apache.taglibs.standard.tag.common.core.OutSupport.doStartTag(OutSupport.java:132)

WARNING: StandardWrapperValve[FormOutputController]: PWC1406: Servlet.service() for servlet FormOutputController threw exception
java.lang.NullPointerException
    at org.apache.jasper.compiler.TagLibraryInfoImpl.toString(TagLibraryInfoImpl.java:129)
    at java.lang.String.valueOf(String.java:2826)
    at java.lang.StringBuilder.append(StringBuilder.java:115)
    at java.util.AbstractMap.toString(AbstractMap.java:490)
    at org.apache.taglibs.standard.tag.common.core.OutSupport.out(OutSupport.java:211)
    at org.apache.taglibs.standard.tag.common.core.OutSupport.doStartTag(OutSupport.java:132)
    at org.apache.jsp.form_005fdebug_jsp._jspx_meth_c_out_1(form_005fdebug_jsp.java from :266)
    at org.apache.jsp.form_005fdebug_jsp._jspx_meth_c_forEach_0(form_005fdebug_jsp.java from :214)
    at org.apache.jsp.form_005fdebug_jsp._jspService(form_005fdebug_jsp.java from :99)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:111)

If I just comment one or the other out, I get no error, and the library works. If I use both, I get this error.

Thanks

回答1:

change your taglib uri to somthing like uri="http://www.example.com/custom_tag_lib"

also change your custom tld properties as follows

custom_tag_lib http://www.example.com/custom_tag_lib

来源：https://stackoverflow.com/questions/16206318/using-jstl-core-lib-fails-when-creating-custom-tag

标签

jsp

jstl

taglib