当调用特定的 servlet 时，我正在尝试使用JExcel Api将数据库中的数据导出到 Excelsheet 中，但是在启动 Tomcat 时出现多个异常。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");
}
}
在本地独立项目中进行测试时，WriteExcel 类中的 writeTestFile() 方法可以正常工作。
当未调用方法 writeTestFile() 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？