关于tag的用法:提示这个错误是为什么?

post your taglib.tld file

解决方案 »

  1.   

    taglib.tld 内容如下:
    <?xml version="1.0" encoding="ISO-8859-1" ?> 
    <!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.1//EN" 
    "http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd"> <taglib> <tlibversion>1.0</tlibversion> <jspversion>1.1</jspversion><shortname>mt</shortname> <uri>http://www.orionserver.com/tutorials/tagtut/lesson1/mytags.jar</uri><info>My first Tag library</info> <tag><name>helloWorld</name><tagclass>com.acme.mytags.HelloWorld</tagclass> <bodycontent>empty</bodycontent> <info>A Hello world Tag</info></tag></taglib>
      

  2.   

    HelloWorld.java 内容:package com.acme.mytags;import javax.servlet.jsp.*;import javax.servlet.jsp.tagext.*;public class HelloWorld implements Tag {
        private PageContext pageContext;     private Tag parent;     public int doStartTag() throws javax.servlet.jsp.JspException 
        {
            return SKIP_BODY; 
        } 
        public int doEndTag() throws javax.servlet.jsp.JspException 
        {
            try 
            { 
                pageContext.getOut().write("Hello World!"); 
            } 
            catch(java.io.IOException e) 
            { 
                throw new JspException("IO Error: " + e.getMessage()); 
            } 
            return EVAL_PAGE; 
        }     public void release() {}     public void setPageContext(final javax.servlet.jsp.PageContext pageContext)
        { 
            this.pageContext=pageContext; 
        } 
        public void setParent(final javax.servlet.jsp.tagext.Tag parent) 
        { 
            this.parent=parent; 
        }
        public javax.servlet.jsp.tagext.Tag getParent() 
        { 
            return parent;
        }
    } 
      

  3.   

    in the web.xml in web-inf, add these lines after <web-app> tag (change the location of taglib.tld if necessary):<taglib>
         <taglib-uri>http://www.orionserver.com/tutorials/tagtut/lesson1/mytags.jar</taglib-uri>
            <taglib-location>/WEB-INF/taglib.tld</taglib-location>
    </taglib>2. change
    <%@ taglib uri="mytags.jar" prefix="mt" %> 
    to
    <%@ taglib uri="http://www.orionserver.com/tutorials/tagtut/lesson1/mytags.jar" prefix="mt" %> 
      

  4.   

    1.我把 taglib.tld 考到/WEB-INF 里一份2.然后在 /WEB-INF/web.xml 的 </web-app> 后添加:
    <taglib>
        <taglib-uri>http://www.orionserver.com/tutorials/tagtut/lesson1/mytags.jar</taglib-uri>
            <taglib-location>/WEB-INF/taglib.tld</taglib-location>
    </taglib>结果不能访问根,然后试将以上内容添加到<web-app></web-app>内,可以访问根.3.修改 /hello.jsp :
    change
    <%@ taglib uri="mytags.jar" prefix="mt" %> 
    to
    <%@ taglib uri="http://www.orionserver.com/tutorials/tagtut/lesson1/mytags.jar" prefix="mt" %> 结果又提示如下错误:
    Error parsing JSP page /hello.jsp line 1
    Error parsing tag-library http://www.orionserver.com/tutorials/tagtut/lesson1/mytags.jar: java.lang.NullPointerException请再帮忙看看.
      

  5.   

    ok, here is what I have on my machine, jakarta-tomcat-4.0-b51.mytag.tld in jakarta-tomcat-4.0-b5\webapps\examples\WEB-INF\jsp\mytag.tld:
    <?xml version="1.0" encoding="ISO-8859-1" ?> 
    <!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.1//EN" 
    "http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd"> 
    <taglib> <tlibversion>1.0</tlibversion> <jspversion>1.1</jspversion>
    <shortname>mt</shortname> <uri>http://www.orionserver.com/tutorials/tagtut/lesson1/mytags.jar</uri>
    <info>My first Tag library</info> 
    <tag>
    <name>helloWorld</name>
    <tagclass>com.acme.mytags.HelloWorld</tagclass> 
    <bodycontent>empty</bodycontent> 
    <info>A Hello world Tag</info>
    </tag>
    </taglib>2. web.xml in \jakarta-tomcat-4.0-b5\webapps\examples\WEB-INF\web.xml:
    ....
    <taglib>
    <taglib-uri>http://www.orionserver.com/tutorials/tagtut/lesson1/mytags.jar</taglib-uri>
    <taglib-location>/WEB-INF/jsp/mytag.tld</taglib-location>
    </taglib>
    ...
    3. HelloWorld.class in jakarta-tomcat-4.0-b5\webapps\examples\WEB-INF\classes\com\acme\mytags\HelloWorld.class4. hello.jsp in jakarta-tomcat-4.0-b5\webapps\examples\jsp\simpletag\hello.jsp:
    <%@ taglib uri="http://www.orionserver.com/tutorials/tagtut/lesson1/mytags.jar" prefix="mt" %> 
    <HTML> 
    <HEAD> 
    <TITLE>Hello World!</TITLE>
    </HEAD> <BODY BGCOLOR="#FFFFFF"> 
    <HR> 
    <mt:helloWorld/>
    <HR> 
    </BODY> 
    </HTML>