在webapp中使用JExcel Api时，Tomcat 7在启动时崩溃

Question

我正在尝试在调用特定servlet时使用JExcel Api将数据从数据库导出到Excel表格中，但在启动Tomcat时，我会遇到多个异常。这是eclipse给出的错误消息：

Nov 01, 2012 10:57:14 AM org.apache.catalina.core.ContainerBase startInternal
SEVERE: A child container failed during start
java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/web]]
    at java.util.concurrent.FutureTask$Sync.innerGet(Unknown Source)
    at java.util.concurrent.FutureTask.get(Unknown Source)
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1123)
    at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:785)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
    at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
    at java.util.concurrent.FutureTask.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/web]]
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)
... 7 more
Caused by: java.lang.NoClassDefFoundError: jxl/write/WriteException
    at java.lang.Class.getDeclaredFields0(Native Method)
    at java.lang.Class.privateGetDeclaredFields(Unknown Source)
    at java.lang.Class.getDeclaredFields(Unknown Source)
    at org.apache.catalina.util.Introspection.getDeclaredFields(Introspection.java:87)
    at org.apache.catalina.startup.WebAnnotationSet.loadFieldsAnnotation(WebAnnotationSet.java:261)
    at org.apache.catalina.startup.WebAnnotationSet.loadApplicationServletAnnotations(WebAnnotationSet.java:140)
    at org.apache.catalina.startup.WebAnnotationSet.loadApplicationAnnotations(WebAnnotationSet.java:67)
    at org.apache.catalina.startup.ContextConfig.applicationAnnotationsConfig(ContextConfig.java:405)
    at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:881)
    at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:369)
    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
    at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5173)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
... 7 more
Caused by: java.lang.ClassNotFoundException: jxl.write.WriteException
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1714)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1559)
... 21 more

Nov 01, 2012 10:57:14 AM org.apache.catalina.core.ContainerBase startInternal
SEVERE: A child container failed during start
java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost]]
    at java.util.concurrent.FutureTask$Sync.innerGet(Unknown Source)
    at java.util.concurrent.FutureTask.get(Unknown Source)
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1123)
    at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:302)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.StandardService.startInternal(StandardService.java:443)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:732)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:684)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:322)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:451)
 Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost]]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
    at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
    at java.util.concurrent.FutureTask.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: org.apache.catalina.LifecycleException: A child container failed during start
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1131)
    at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:785)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
... 7 more

Nov 01, 2012 10:57:14 AM org.apache.catalina.startup.Catalina start
SEVERE: Catalina.start: 
org.apache.catalina.LifecycleException: Failed to start component [StandardServer[8005]]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:684)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:322)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:451)
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardService[Catalina]]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)
    at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:732)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
... 7 more
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina]]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)
    at org.apache.catalina.core.StandardService.startInternal(StandardService.java:443)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
... 9 more
Caused by: org.apache.catalina.LifecycleException: A child container failed during start
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1131)
    at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:302)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
... 11 more

这是servlet代码：

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import jxl.write.WriteException;


/**
 * Servlet implementation class Test
 */
@WebServlet(description = "A simple test.", urlPatterns = { "/test" })

public class Test extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public Test() {
        super();
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        try {
            WriteExcel.writeTestFile();
        } catch (WriteException e) {
            e.printStackTrace();
        }

        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        out.println("<html>");
        out.println("<head>");
        out.println("<title>Test!</title>");
        out.println("</head>");
        out.println("<body>");
        out.println("I've written an Excel file!");
        out.println("</body>");
        out.println("</html>");

    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

}

这是WriteExcel类的代码：

import java.io.File;
import java.io.IOException;
import java.util.Locale;

import jxl.CellView;
import jxl.Workbook;
import jxl.WorkbookSettings;
import jxl.format.UnderlineStyle;
import jxl.write.Formula;
import jxl.write.Label;
import jxl.write.Number;
import jxl.write.WritableCellFormat;
import jxl.write.WritableFont;
import jxl.write.WritableSheet;
import jxl.write.WritableWorkbook;
import jxl.write.WriteException;
import jxl.write.biff.RowsExceededException;

//tomcat hat probleme mit der jxl library
public class WriteExcel {

  private WritableCellFormat timesBoldUnderline;
  private WritableCellFormat times;
  private String inputFile;

public void setOutputFile(String inputFile) {
  this.inputFile = inputFile;
  }

  public void write() throws IOException, WriteException {
    File file = new File(inputFile);
    WorkbookSettings wbSettings = new WorkbookSettings();

    wbSettings.setLocale(new Locale("en", "EN"));

    WritableWorkbook workbook = Workbook.createWorkbook(file, wbSettings);
    workbook.createSheet("Report", 0);
    WritableSheet excelSheet = workbook.getSheet(0);
    createLabel(excelSheet);
    createContent(excelSheet);

    workbook.write();
    workbook.close();
  }

  private void createLabel(WritableSheet sheet)
      throws WriteException {
    // Lets create a times font
    WritableFont times10pt = new WritableFont(WritableFont.TIMES, 10);
    // Define the cell format
    times = new WritableCellFormat(times10pt);
    // Lets automatically wrap the cells
    times.setWrap(true);

    // Create create a bold font with unterlines
    WritableFont times10ptBoldUnderline = new WritableFont(WritableFont.TIMES, 10, WritableFont.BOLD, false,
        UnderlineStyle.SINGLE);
    timesBoldUnderline = new WritableCellFormat(times10ptBoldUnderline);
    // Lets automatically wrap the cells
    timesBoldUnderline.setWrap(true);

    CellView cv = new CellView();
    cv.setFormat(times);
    cv.setFormat(timesBoldUnderline);
    cv.setAutosize(true);

    // Write a few headers
    addCaption(sheet, 0, 0, "Header 1");
    addCaption(sheet, 1, 0, "This is another header");


  }

  private void createContent(WritableSheet sheet) throws WriteException,
      RowsExceededException {
    // Write a few number
    for (int i = 1; i < 10; i++) {
      // First column
      addNumber(sheet, 0, i, i + 10);
      // Second column
      addNumber(sheet, 1, i, i * i);
    }
    // Lets calculate the sum of it
    StringBuffer buf = new StringBuffer();
    buf.append("SUM(A2:A10)");
    Formula f = new Formula(0, 10, buf.toString());
    sheet.addCell(f);
    buf = new StringBuffer();
    buf.append("SUM(B2:B10)");
    f = new Formula(1, 10, buf.toString());
    sheet.addCell(f);

    // Now a bit of text
    for (int i = 12; i < 20; i++) {
      // First column
      addLabel(sheet, 0, i, "Boring text " + i);
      // Second column
      addLabel(sheet, 1, i, "Another text");
    }
  }

  private void addCaption(WritableSheet sheet, int column, int row, String s)
      throws RowsExceededException, WriteException {
    Label label;
    label = new Label(column, row, s, timesBoldUnderline);
    sheet.addCell(label);
  }

  private void addNumber(WritableSheet sheet, int column, int row,
      Integer integer) throws WriteException, RowsExceededException {
    Number number;
    number = new Number(column, row, integer, times);
    sheet.addCell(number);
  }

  private void addLabel(WritableSheet sheet, int column, int row, String s)
      throws WriteException, RowsExceededException {
    Label label;
    label = new Label(column, row, s, times);
    sheet.addCell(label);
  }


  public static void writeTestFile() throws WriteException, IOException {
    WriteExcel test = new WriteExcel();
    test.setOutputFile("d:/test.xls");
    test.write();
    System.out.println("Please check the result file under d:/test.xls");
  }

} 

在本地独立项目中测试时，WriteExcel类中的writeTestFile（）方法可以正常工作。
当没有调用writeTestFile（）方法时，servlet本身也可以工作。

有人可以澄清为什么我会得到例外吗？ 还有修复或解决方法吗？

Answer 1

试试这个：双击服务器，点击“打开启动配置”，转到Classpath选项卡，然后在User Entries下添加jar。