java - 从jsp调用java方法

Question

我正在从 jsp 调用我的 java 方法，它给出 NoClassDefFoundError: error。

但是当我从 main 方法调用时，我的方法正在工作。 我在代码中使用了 xlrd jar，并且还放置了 jar lib 文件夹。但仍然给出错误。

异常跟踪:

org.apache.jasper.JasperException: An exception occurred processing JSP page /exportDSD.jsp at line 20

17:     //excel.getExcel();
18:     
19:     Report r = new Report();
20:     r.generateReport();
21:     
22:     System.out.println("Generated DSD");
23: %> 

堆栈跟踪:

org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:568)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:455)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

根本原因:

javax.servlet.ServletException: java.lang.NoClassDefFoundError: xlrd/Workbook
    org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:916)
    org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:845)
    org.apache.jsp.exportDSD_jsp._jspService(exportDSD_jsp.java:107)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

我的代码:

import org.apache.poi.hssf.usermodel.HSSFCell; 
 import org.apache.poi.hssf.usermodel.HSSFCellStyle; 
 import org.apache.poi.hssf.usermodel.HSSFDataFormat; 
 import org.apache.poi.hssf.usermodel.HSSFRow; 
 import org.apache.poi.hssf.usermodel.HSSFSheet; 
 import org.apache.poi.hssf.usermodel.HSSFWorkbook; 
 import xlrd.*;

 public void generateReport() throws BiffException, ClassNotFoundException, SQLException, IOException { 
 ... ... 
 } 

从 jsp 我这样调用:

<% Report r =new Report(); r.generateReport(); %>

Answer 1

出现 JSP 导入不正确:

Add jar in WEB-INF/lib
Add <%@ page import="xlrd.*" %> to the top of your JSP

要导入多个类，请使用以下格式:

<%@ page import="com.sample.Report,xlrd.*" %>