严重: Servlet.service() for servlet [jsp] in context with path [/Biaoqian] threw exception [/1.jsp (line: 16, column: 1) Unable to load tag handler class "com.showId.Id.ShowId" for tag "ShowId:ShowId"] with root cause
org.apache.jasper.JasperException: /1.jsp (line: 16, column: 1) Unable to load tag handler class "com.showId.Id.ShowId" for tag "ShowId:ShowId"
at org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:42)
at org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:443)
at org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:199)
at org.apache.jasper.compiler.Parser.parseCustomTag(Parser.java:1219)
at org.apache.jasper.compiler.Parser.parseElements(Parser.java:1446)
at org.apache.jasper.compiler.Parser.parse(Parser.java:138)
at org.apache.jasper.compiler.ParserController.doParse(ParserController.java:242)
at org.apache.jasper.compiler.ParserController.parse(ParserController.java:102)
at org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:199)
at org.apache.jasper.compiler.Compiler.compile(Compiler.java:374)
at org.apache.jasper.compiler.Compiler.compile(Compiler.java:354)
at org.apache.jasper.compiler.Compiler.compile(Compiler.java:341)
at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:662)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:364)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
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.StandardWrapperValve.invoke(StandardWrapperValve.java:218)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:956)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:442)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1082)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:623)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)

 

（1）自定义标签错误，这个错误多半是eclipse引起的，我的myeclipse就不会出现这个错误，主要原因是eclipse无法生成目标的.class文件,解决方案就是让它自己生成.class文件，选择Project-->Build Automatically(自动生成class)，服务器就会找到它。或许还会发生ClassNotFound问题，在web.xml中加入jsp的路径即可。

（2）或者更改Tomcat配置，选择window ----show view－－－services可以看到服务的面板，,双击tomcat进入配置界面Service Locations（Specify the server path (i.e. catalina.base) and deploy path. Server must be published with no modules present to make changes.）选项变灰色无法更改配置。若要更改，Project---->clean之后设置启动后将又变为黑色。更改Service Locations默认选项为：