在 /var/lib/tomcat6/webapps/ROOT 我有以下结构 =>
META-INF teiExample.jsp WEB-INF
./META-INF:
context.xml
./WEB-INF:
exampleTags.tld lib web.xml
./WEB-INF/lib:
example.jar
example.jar 的内容 =>
META-INF/
META-INF/MANIFEST.MF
classes/utilities/arrayExtraInfo.class
classes/utilities/createArrayTag.class
exampleTags.tld
teiExample.jsp =>
<%@ taglib prefix="example" uri="exampleURI" %>
<html>
<head>
<title>Welcome and time example</title>
</head>
<body>
<example:createArray name="theArray" />
We are now using a JAR file<BR />
The array has <%= theArray.length %> items.<BR />
</body>
</html>
exampleTags.tld =>
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN" "http://java.sun.com/dtd/web-jsptaglibrary_1_2.dtd">
<taglib>
<tlib-version>1.0</tlib-version>
<jsp-version>1.2</jsp-version>
<short-name>ExampleTags</short-name>
<uri>exampleURI</uri>
<description>A set of example tag handlers.</description>
<tag>
<name>createArray</name>
<tag-class>utilities.createArrayTag</tag-class>
<tei-class>utilities.arrayExtraInfo</tei-class>
<attribute>
<name>name</name>
</attribute>
</tag>
</taglib>
web.xml =>
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/j2ee/dtds/web-app_2_3.dtd">
<web-app>
<taglib>
<taglib-uri>exampleTags</taglib-uri>
<taglib-location>/WEB-INF/exampleTags.tld</taglib-location>
</taglib>
</web-app>
但我得到的只是=>
HTTP Status 500 -
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
org.apache.jasper.JasperException: Failed to load or instantiate TagExtraInfo class: utilities.arrayExtraInfo
org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:51)
org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:409)
org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:281)
org.apache.jasper.compiler.TagLibraryInfoImpl.createTagInfo(TagLibraryInfoImpl.java:419)
org.apache.jasper.compiler.TagLibraryInfoImpl.parseTLD(TagLibraryInfoImpl.java:250)
org.apache.jasper.compiler.TagLibraryInfoImpl.<init>(TagLibraryInfoImpl.java:163)
org.apache.jasper.compiler.Parser.parseTaglibDirective(Parser.java:382)
org.apache.jasper.compiler.Parser.parseDirective(Parser.java:445)
org.apache.jasper.compiler.Parser.parseElements(Parser.java:1392)
org.apache.jasper.compiler.Parser.parse(Parser.java:130)
org.apache.jasper.compiler.ParserController.doParse(ParserController.java:255)
org.apache.jasper.compiler.ParserController.parse(ParserController.java:103)
org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:170)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:332)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:312)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:299)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:589)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:317)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
root cause
java.lang.ClassNotFoundException: utilities.arrayExtraInfo
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1484)
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1329)
org.apache.jasper.compiler.TagLibraryInfoImpl.createTagInfo(TagLibraryInfoImpl.java:416)
org.apache.jasper.compiler.TagLibraryInfoImpl.parseTLD(TagLibraryInfoImpl.java:250)
org.apache.jasper.compiler.TagLibraryInfoImpl.<init>(TagLibraryInfoImpl.java:163)
org.apache.jasper.compiler.Parser.parseTaglibDirective(Parser.java:382)
org.apache.jasper.compiler.Parser.parseDirective(Parser.java:445)
org.apache.jasper.compiler.Parser.parseElements(Parser.java:1392)
org.apache.jasper.compiler.Parser.parse(Parser.java:130)
org.apache.jasper.compiler.ParserController.doParse(ParserController.java:255)
org.apache.jasper.compiler.ParserController.parse(ParserController.java:103)
org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:170)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:332)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:312)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:299)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:589)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:317)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
note The full stack trace of the root cause is available in the Apache Tomcat/6.0.24 logs.
Apache Tomcat/6.0.24
为什么要这样？而且，我是否需要 web.xml？
最佳答案
org.apache.jasper.JasperException: Failed to load or instantiate TagExtraInfo class: utilities.arrayExtraInfo
这只是意味着在幕后
TagExtraInfo tag = (TagExtraInfo) Class.forName("utilities.arrayExtraInfo").newInstance();
失败了。
即该类不存在于类路径中，或者没有默认的无参数构造函数。然而，真正的根本原因应该存在于堆栈跟踪中。在堆栈跟踪中进一步阅读，最底部的部分是问题的真正根本原因。
在您的情况下，类名不正确。在构建 JAR 时，类名应该是 classes.utilities.arrayExtraInfo 或者您应该删除 JAR 中的 /classes 文件夹。
与具体问题无关:请阅读 Java Naming Conventions .类名应该以大写开头。
关于jsp jar加载失败，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/5857602/