The server encountered an internal error () that prevented it from fulfilling this request.

以下是SERVLET的代码，昨晚还可以顺利使用的
package poi;import java.io.FileInputStream;
import java.io.IOException;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.poifs.filesystem.POIFSFileSystem;public class GetAttribute extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
} public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
try { FileInputStream fileIn = new FileInputStream("F:\\workspace\\poi\\workbook.xls");
POIFSFileSystem fs = new POIFSFileSystem(fileIn);
HSSFWorkbook wb = new HSSFWorkbook(fs);
HSSFSheet sheet = wb.getSheetAt(0);
int row1 = Integer.parseInt(request.getParameter("row")) - 1;
HSSFRow row = sheet.getRow(row1);
short cell1 = (short) (Integer.parseInt(request.getParameter("cell")) - 1);
HSSFCell cell = row.getCell(cell1);

request.setAttribute("cell", cell);
String att = request.getParameter("att");

if (att.equals("Cell")) {
request.getRequestDispatcher("./CellAtt").forward(request,response);
} else if (att.equals("CellStyle")){
request.getRequestDispatcher("/ShowCellStyle.jsp").forward(request,response);
}else{
request.getRequestDispatcher("./Font").forward(request,response);
} } catch (Exception e) {
e.printStackTrace();
System.out.println("error in servlet");
}
request.getRequestDispatcher("/error.jsp"); }
}