我需要显示新生成的Excel （来自使用Apache POI的表格）在网络浏览器中（不管是什么，Firefox， Opera或IE）。我用
创建了JSP文件
contentType="application/vnd.ms-excel"
但我没有得到它。
这是我的代码段：
<%@page session="true" contentType="application/vnd.ms-excel" pageEncoding="UTF-8"%>
<%@page import="org.apache.poi.ss.usermodel.CellStyle"%>
<%@page import="java.sql.DriverManager"%>
<%@page import="java.sql.ResultSet"%>
<%@page import="java.sql.Statement"%>
<%@page import="java.sql.Connection"%>
<%@page import="org.apache.poi.ss.usermodel.CreationHelper"%>
<%@page import="org.apache.poi.hssf.usermodel.HSSFCell"%>
<%@page import="org.apache.poi.hssf.usermodel.HSSFRow"%>
<%@page import="org.apache.poi.hssf.usermodel.HSSFWorkbook"%>
<%@page import="org.apache.poi.hssf.usermodel.HSSFSheet"%>
<html>
<head>
<%!
int r=0;
HSSFWorkbook book;
HSSFSheet sheet;
HSSFRow row;
CreationHelper createHelper = book.getCreationHelper();
Connection conn;
Statement stmt;
ResultSet rs;
%>
<title>Report</title>
<%
book = new HSSFWorkbook();
sheet = book.createSheet("Report");
%>
</head>
<body>
<%
try {
// Header of the Excel File
row = sheet.createRow(r);
row.createCell(0).setCellValue("Visit ID");
row.createCell(1).setCellValue("Carrier Name");
row.createCell(2).setCellValue("Phone Number");
row.createCell(3).setCellValue("Patient Name");
row.createCell(4).setCellValue("Subscriber ID");
row.createCell(5).setCellValue("Subscriber Name");
row.createCell(6).setCellValue("Chart Number");
row.createCell(7).setCellValue("Date Of Birth");
row.createCell(8).setCellValue("Subscriber Employer");
row.createCell(9).setCellValue("Service Date");
row.createCell(10).setCellValue("Provider Name");
row.createCell(11).setCellValue("CPT Code");
row.createCell(12).setCellValue("Aging Date");
row.createCell(13).setCellValue("Total");
row.createCell(14).setCellValue("Follow Up Notes");
row.createCell(15).setCellValue("Internal Status Code");
CellStyle cellStyle = book.createCellStyle();
cellStyle.setDataFormat(createHelper.createDataFormat().getFormat("MM/dd/yyyy"));
Statement stNotes;
ResultSet rsNotes;
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/maintain", "root", "root");
stmt = conn.createStatement();
stNotes = conn.createStatement();
rs = stmt.executeQuery("SELECT b.VisitID, b.CarrierName, b.PhoneNum, b.PatientName, "
+ "b.SubscriberID, b.SubscriberName, b.ChartNum, b.DoB, b.SubscriberEmp, "
+ "b.ServiceDate, b.ProviderName, b.CPTCode, b.BillingDate, b.BalanceAmt "
+ "FROM billing b INNER JOIN followup f ON b.VisitID = f.VisitID GROUP BY VisitID");
while(rs.next()) {
r++;
row = sheet.createRow(r);
row.createCell(0).setCellValue(rs.getString("VisitID"));
row.createCell(1).setCellValue(rs.getString("CarrierName"));
row.createCell(2).setCellValue(rs.getString("PhoneNum"));
row.createCell(3).setCellValue(rs.getString("PatientName"));
row.createCell(4).setCellValue(rs.getString("SubscriberID"));
row.createCell(5).setCellValue(rs.getString("SubscriberName"));
row.createCell(6).setCellValue(rs.getString("ChartNum"));
row.createCell(7).setCellValue(rs.getString("DoB"));
row.createCell(8).setCellValue(rs.getString("SubscriberEmp"));
row.createCell(9).setCellValue(rs.getString("ServiceDate"));
row.createCell(9).setCellStyle(cellStyle);
row.createCell(10).setCellValue(rs.getString("ProviderName"));
row.createCell(11).setCellValue(rs.getString("CPTCode"));
row.createCell(12).setCellValue(rs.getString("BillingDate"));
row.createCell(12).setCellStyle(cellStyle);
row.createCell(13).setCellValue(rs.getString("BalanceAmt"));
rsNotes = stNotes.executeQuery("SELECT Date, InternalStatusCode, FollowUpNote "
+ "FROM followup WHERE VisitID='" + rs.getString("VisitID") + "' ORDER BY Date");
while(rsNotes.next()) {
row.createCell(14).setCellValue(rsNotes.getString("Date") + " - " + rsNotes.getString("FollowUpNote"));
row.createCell(15).setCellValue(rs.getString("VisitID"));
}
}
}
catch(ClassNotFoundException cnf) {
out.print("<br> Error : MySQL Driver not found. <br>");
}
catch(Exception ex) {
out.print("Error : <br>" + ex);
}
%>
</body>
</html>
我正在使用Tomcat 6.0.26获取此异常：
exception
org.apache.jasper.JasperException: java.lang.NullPointerException
org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:156)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:329)
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)
org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
root cause
java.lang.NullPointerException
org.apache.jsp.GetReport_jsp.<init>(GetReport_jsp.java:29)
sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
java.lang.reflect.Constructor.newInstance(Constructor.java:513)
java.lang.Class.newInstance0(Class.java:355)
java.lang.Class.newInstance(Class.java:308)
org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:145)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:329)
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)
org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
我错过了什么或有什么不对吗？ 有人可以帮我摆脱这个问题吗？
提前完成。
答案 0 :(得分：8)
你试图这样做的方式没有任何意义。您不能将HTML与Excel混合使用。最好创建一个servlet而不是JSP页面，让这个servlet只输出Excel文件而不输出任何其他内容。
这样的事情：
import java.io.*;
import javax.servlet.http.*;
import javax.servlet.*;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
// ... plus all the other libs you need
public class ExcelServlet extends HttpServlet {
public void doGet (HttpServletRequest req,
HttpServletResponse res)
throws ServletException, IOException
{
HSSFWorkbook book;
// ...
// fill the book
// ...
res.setContentType("application/vnd.ms-excel");
book.write(res.getOutputStream());
res.getOutputStream().close();
}
}
答案 1 :(得分：3)
HSSFWorkbook book;
HSSFSheet sheet;
HSSFRow row;
CreationHelper createHelper = book.getCreationHelper();
在初始化之前，您正在使用book对象。
答案 2 :(得分：2)
我建议不要这样做。
JSP中的Scriptlet代码完全错误。
将数据库访问放在这样的页面中也不好。
更好的方法是Spring MVC及其JExcelView。
答案 3 :(得分：0)
以下是有关如何调试JSP异常的提示：
堆栈跟踪中的，这个类
java.lang.NullPointerException
org.apache.jsp.GetReport_jsp.<init>(GetReport_jsp.java:29)
是GetReport.jsp的生成java类。您可以查看$TOMCAT_HOME/work/<enginename>/<hostname>/<appname>文件夹以查看生成的实际代码，并查看第29行的确切内容。
答案 4 :(得分：0)
查看SourceForge中的WorkbookTag项目，它完全符合您的需求：使用Apache POI进行HTML工作表呈现... WorkbookTag