Internal Servlet Error: 应该怎么解决

Question

test.jsp<form method="post" action="test1.jsp">
<textarea rows="5" name="lr"></textarea>
<input type="submit">tetst1.jsp<%
    StringTokenizer line=new StringTokenizer(lr,"\\");
    while(line.hasMoreTokens()){
        out.println("<font color=blue>"+line.nextToken()+":</font>");
    }
%>在提交表单时，出现下面错误，该怎么解决？Error: 500Internal Servlet Error:javax.servlet.ServletException
at org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:459)
at manage._0002fmanage_0002fcheckeshop_0002ejspcheckeshop_jsp_29._jspService(_0002fmanage_0002fcheckeshop_0002ejspcheckeshop_jsp_29.java:194)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:119)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.jasper.servlet.JspServlet$JspCountedServlet.service(JspServlet.java:130)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.jasper.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:282)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:429)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:500)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.tomcat.core.ServletWrapper.doService(ServletWrapper.java:405)
at org.apache.tomcat.core.Handler.service(Handler.java:287)
at org.apache.tomcat.core.ServletWrapper.service(ServletWrapper.java:372)
at org.apache.tomcat.core.ContextManager.internalService(ContextManager.java:812)
at org.apache.tomcat.core.ContextManager.service(ContextManager.java:758)
at org.apache.tomcat.service.http.HttpConnectionHandler.processConnection(HttpConnectionHandler.java:213)
at org.apache.tomcat.service.TcpWorkerThread.runIt(PoolTcpEndpoint.java:416)
at org.apache.tomcat.util.ThreadPool$ControlRunnable.run(ThreadPool.java:501)
at java.lang.Thread.run(Thread.java:484)Root cause: 
java.lang.NullPointerException
at java.util.StringTokenizer.(StringTokenizer.java:122)
at java.util.StringTokenizer.(StringTokenizer.java:138)
at manage._0002fmanage_0002fcheckeshop_0002ejspcheckeshop_jsp_29._jspService(_0002fmanage_0002fcheckeshop_0002ejspcheckeshop_jsp_29.java:96)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:119)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.jasper.servlet.JspServlet$JspCountedServlet.service(JspServlet.java:130)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.jasper.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:282)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:429)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:500)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.tomcat.core.ServletWrapper.doService(ServletWrapper.java:405)
at org.apache.tomcat.core.Handler.service(Handler.java:287)
at org.apache.tomcat.core.ServletWrapper.service(ServletWrapper.java:372)
at org.apache.tomcat.core.ContextManager.internalService(ContextManager.java:812)
at org.apache.tomcat.core.ContextManager.service(ContextManager.java:758)
at org.apache.tomcat.service.http.HttpConnectionHandler.processConnection(HttpConnectionHandler.java:213)
at org.apache.tomcat.service.TcpWorkerThread.runIt(PoolTcpEndpoint.java:416)
at org.apache.tomcat.util.ThreadPool$ControlRunnable.run(ThreadPool.java:501)
at java.lang.Thread.run(Thread.java:484)

Answer 1

你test1。jsp里面是想取lr里的文本或者字符串，但是lr是test。jsp里的一个文本区，在test1。jsp里是不能直接访问的
String str = request.getParameter("lr");
StringTokenizer line=new StringTokenizer(str,"\\");